HK1224015B - Color-sensitive image sensor with embedded microfluidics and associated methods - Google Patents

Description

Color sensing image sensor with embedded microfluidics and related methods

Technical Field

The present invention relates to the field of optics, and more particularly to color sensing image sensors with embedded microfluidics and related methods.

Background Art

Biological or chemical test results are often determined using optical imaging methods. Fluorescence or chemiluminescence imaging-based test data interpretation is replacing more traditional methods such as gel electrophoresis, non-imaging flow cytometry, and mass spectrometry. Fluorescence and chemiluminescence imaging are particularly well-suited for multi-task (complex) test data interpretation because color and spatial location information can distinguish different types of sample components or processes.

Modern optical imaging-based diagnostic instruments utilize digital image sensors such as charge-coupled device (CCD) sensors or complementary metal oxide semiconductor (CMOS) image sensors. While CCD image sensors, once the preferred type of image sensor due to their high sensitivity, are less common than even a decade ago, CMOS image sensors are gradually taking over the market. CMOS image sensors are associated with significantly lower manufacturing costs compared to CCD sensors and are steadily improving in performance. Many applications requiring particularly high sensitivity now utilize so-called backside-illuminated CMOS image sensors, which, by placing the electrical connections to the photodiodes away from the optical path, improve light collection efficiency compared to traditional front-illuminated CMOS image sensors. These developments have led to a widespread reduction in the cost of image sensors for optical imaging-based diagnostic instruments. In many cases, instrument cost is dominated by other components such as optics (e.g., lenses, filters, and mirrors) and fluidics.

Currently, significant efforts are underway to develop compact, low-cost optical imaging systems, particularly for use at the point of care and/or in low-resource settings. However, such imaging systems typically cost several thousand dollars, which can hinder market acceptance. Furthermore, systems for point-of-care and/or low-resource settings must be rugged, maintenance-free, and operable by minimally trained staff, making it particularly challenging to meet cost requirements. For these reasons, many point-of-care and/or low-resource settings rely on laminar flow biosensor assays for data interpretation, resulting in poor quantification (if any), limited multitasking capabilities (if any), and subjective readouts. Consequently, patients in these settings receive suboptimal treatment options.

Summary of the Invention

In one embodiment, a color image sensor having embedded microfluidics includes a silicon substrate having (a) at least one recess partially defining at least one embedded microfluidic channel and (b) a plurality of photosensitive regions, wherein at least two photosensitive regions are respectively located at at least two different depth ranges relative to the at least one recess, for generating position-sensing electronic signals in response to light from the at least one recess to provide color information.

In one embodiment, a method for generating a color image of a fluid sample includes performing imaging of the fluid sample deposited in a microfluidic channel embedded in a silicon substrate, onto a plurality of photosensitive regions of the silicon substrate, and generating color information based on the depth of light penetration into the silicon substrate.

In one embodiment, a wafer-level method for fabricating a plurality of color image sensors with embedded microfluidics includes: (a) processing the front side of a silicon wafer to produce a plurality of doped regions, wherein the doped regions are located at a plurality of depth ranges relative to a plane of a back side of the silicon wafer, (b) processing the back side to partially define a plurality of embedded microfluidic channels by forming recesses in the plane of the back side having depths relative to the plane of the back side, such that the different depth ranges correspond to penetration depths of light of different wavelength ranges from the recesses into the silicon wafer, and (c) dicing the silicon wafer to separate the color image sensors, wherein each color image sensor includes at least one embedded microfluidic channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a color image sensor with embedded microfluidics, according to an embodiment.

FIG. 2 shows a wavelength-dependent depth plot of light penetration into silicon.

3 illustrates a color-sensing image sensor with embedded microfluidics that includes photosensitive regions for detecting light in non-overlapping wavelength ranges, according to an embodiment.

4 illustrates a color-sensing image sensor with embedded microfluidics that includes photosensitive regions for detecting light in overlapping wavelength ranges, according to one embodiment.

5 illustrates a color-sensing image sensor with embedded microfluidics that includes photosensitive regions for detecting light in overlapping wavelength ranges, according to one embodiment.

FIG. 6 illustrates a layout of color pixel groups of the color sensing image sensor of FIG. 1 according to one embodiment.

FIG. 7 illustrates another layout of color pixel groups of the color sensing image sensor of FIG. 1 according to one embodiment.

FIG. 8 illustrates another layout of color pixel groups of the color sensing image sensor of FIG. 1 according to one embodiment.

9A illustrates lensless imaging of sample components using the color-sensing image sensor of FIG. 1 , according to one embodiment.

FIG. 9B illustrates a portion of the color-sensing image sensor of FIG. 1 , according to one embodiment.

FIG. 10 illustrates a color sensing image sensor with multi-layer microfluidics according to one embodiment.

FIG. 11 illustrates a color-sensing image sensor configured to reduce spectral blur, according to one embodiment.

12 illustrates a sample imaging system that utilizes the color sensing image sensor of FIG. 1 to generate a color image of a fluid sample, according to an embodiment.

13 illustrates a method for generating a color image of a fluid sample using a color sensing image sensor with embedded microfluidics, according to an embodiment.

14 illustrates a method for color fluorescence imaging of a fluid sample using a color-sensing image sensor with embedded microfluidics, according to an embodiment.

15 illustrates a flow chart of a wafer-level method for fabricating a plurality of color-sensing image sensors with embedded microfluidics, according to an embodiment.

FIG16 illustrates the steps of the method of FIG15 according to an embodiment.

DETAILED DESCRIPTION

FIG1 illustrates, in a cross-sectional side view, a color sensing image sensor 100 with embedded microfluidics for lensless color imaging of a fluid sample 150. The color sensing image sensor 100 provides a compact, inexpensive, and easily operable solution for imaging fluid samples and is suitable for use as a diagnostic device, for example, at the point of care and/or in resource-poor settings. The color sensing image sensor 100 can be manufactured using low-cost wafer-scale CMOS technology. Certain embodiments of the color sensing image sensor 100 can be manufactured cost-compatibly for single-use scenarios, where the color sensing image sensor 100 is used only once and then discarded. Furthermore, the color sensing image sensor 100 can image the fluid sample 150 with high resolution and sensitivity. The color sensing image sensor 100 generates both spatial and color information of the fluid sample 150 and is therefore well-suited for multitasking (composite) output data analysis and/or processing associated with the fluid sample 150.

Color sensing image sensor 100 includes a silicon substrate 110 having a plurality of photosensitive regions 114, a plurality of photosensitive regions 115, a recess 112, and electronic circuitry 130. As used herein, a "silicon substrate" refers to a substrate based on silicon and/or silicon derivatives such as silicon germanium and silicon carbide. A "silicon substrate," as referred to herein, may include: (a) dopants that locally modify the properties of the silicon or silicon-derived material; and (b) conductive materials, such as metals, to form electronic circuitry.

The color sensing image sensor 100 may also include a cover 120. In the color sensing image sensor 100, the recess 112 and the cover 120 together define an embedded microfluidic channel. The cover 120 includes through holes 122, which are formed as inlet and outlet ports of the microfluidic channel associated with the recess 112. It should be understood that the cover 120 can be provided separately from the silicon substrate 110 so that the color sensitive image sensor 100 can exist, be manufactured and/or be sold without the cover 120. In a particular embodiment, the recess 112 is generally planar. The recess 112 has a depth 188 relative to the surface of the silicon substrate 110 that contacts the cover 120, such that the recess 112 and the cover 120 cooperate to define a microfluidic channel having a height equal to the depth 188. The depth 188 is, for example, in a range between a fraction of a micron and several millimeters.

Color-sensing image sensor 100 determines color information based on the wavelength-dependent penetration depth of light entering silicon substrate 110 from recess 112. Photosensitive regions 114 and 115 generate electronic signals in response to light incident thereon. Photosensitive regions 114 and 115 are located at different depths 184 and 185, respectively, relative to recess 112. Depths 184 and 185 correspond to the depth ranges occupied by photosensitive regions 114 and 115, respectively. Photosensitive regions 114 and 115, in response to light entering silicon substrate 110 from recess 112, have penetration depths that coincide with depths 184 and 185, respectively.

Figure 2 shows two plots 200 and 220 illustrating the wavelength-dependent penetration depth 210 of light into silicon. Plot 200 shows the penetration depth 210 of light into silicon over a wavelength range from 400 nanometers (nm) to 1100 nm. Plot 200 plots the penetration depth 210 of visible light into silicon as measured at 90% penetration on a logarithmic scale of micrometers (axis 204) versus the wavelength in nanometers (axis 202). Plot 220 shows the penetration depth 210 of visible light into silicon. Plot 220 plots the penetration depth 210 of visible light into silicon as measured at 90% penetration on a linear scale of micrometers (axis 208) versus the wavelength in nanometers (axis 206). As shown in plots 200 and 220, the penetration depth of light into silicon is highly dependent on wavelength. Furthermore, the penetration depth of light into silicon depends monotonically on wavelength. Therefore, there is a one-to-one (intercalated) correspondence between penetration depth and wavelength. The visible spectrum spans a penetration depth range from 0.19 microns (for a wavelength of 400 nanometers) to 16 microns (for a wavelength of 750 nanometers). This penetration depth range is greater than the resolution of silicon fabrication, but small enough to be compatible with the expected thickness of silicon substrate 110 (FIG. 1).

Referring again to FIG. 1 , because the penetration depth of light into silicon substrate 110 is wavelength-dependent (as shown in FIG. 2 ), photosensitive regions 114 and 115 are sensitive to light of different wavelength ranges. Therefore, photosensitive regions 114 and 115 provide color resolution. Color sensing image sensor 100 is configured with color pixel groups 118 . Each color pixel group 118 includes at least one photosensitive region 114 and at least one photosensitive region 115 . For clarity, only one color pixel group 118 is shown in FIG. Color sensing image sensor 100 may include any number of color pixel groups 118 to achieve a desired resolution. For example, the color sensing image sensor may include an array of one thousand to several million color pixel groups 118 , wherein each color pixel group 118 has a cross-sectional area ranging from approximately 1 square micron to 100 square microns.

Without departing from the scope of the present invention, color pixel group 118 may include one or more additional photosensitive regions located at depths other than depths 184 and 185 that are sensitive to light of wavelength range(s) different from the wavelength range associated with photosensitive regions 114 and 115. In one example, color pixel group 118 also includes photosensitive region 116 located at depth 186, which is different from depths 184 and 185, to enable color sensing image sensor 100 to distinguish light of three different wavelength ranges. As shown in FIG. 2 , color sensing image sensor 100 can be configured with photosensitive regions 114 and 115, and optionally photosensitive region 116, associated with different portions of the visible light spectrum at respective depths 184, 185, and 186. In a particular embodiment, color sensing image sensor 100 is configured with photosensitive regions 114, 115, and 116 that enable differentiation of light belonging to the red, green, and blue portions of the visible light spectrum. However, the photosensitive regions 114, 115, and 116 may have depths different than those shown in FIG1 without departing from the scope of the present invention. For example, the depth ranges of two or more photosensitive regions 114, 115, and 116 may overlap. Certain exemplary configurations are discussed below with reference to FIG3-5.

In one embodiment, the photosensitive regions 114, 115, and 116 are negatively doped (n-type doped) regions of the silicon substrate 110. In another embodiment, the photosensitive regions 114, 115, and 116 are positively doped (p-type doped) regions of the silicon substrate 110. The photosensitive regions 114, 115, and optionally 116 are communicatively coupled to the electronic circuit 130 via electrical connections 132. For clarity of illustration, only one electrical connection 132 is labeled in FIG1 . The electronic circuit 130 processes the electronic signals generated by the photosensitive regions 114, 115, and optionally 116 in response to light and outputs an electronic signal 140. The electronic signal 140 includes position-sensing color information and is therefore representative of a color image of the fluid sample 150 deposited in the microfluidic channel defined by the recess 112 and the cover 120.

Since electrical connection 132 is located away from the optical path from recess 112 to photosensitive areas 114, 115, and 116, color sensing image sensor 100 can be implemented as a backside-illuminated CMOS image sensor. Therefore, color sensing image sensor 100 can benefit from higher light collection efficiency than a frontside-illuminated CMOS image sensor.

In one embodiment, the electronic circuit 130 is communicatively coupled to a processing module 142. The processing module 142 includes a color calculator 144 that processes the electronic signal 140 to assign a color or multiple color values, such as the intensities of red, green, and blue light, to the color pixel group 118. The processing module 142 can thereby output a color image 146 of the fluid sample 150.

In another embodiment, processing module 142 is integrated into color sensing image sensor 100. In one example, processing module 142 is located on an electronic circuit board that also houses color sensing image sensor 100. In another example, processing module 142 is integrated into electronic circuit 130. Processing module 142 can function as logic gates to perform algebraic operations on the electronic signals generated by photosensitive regions 114, 115, and optionally 116.

In one exemplary usage scenario, the light source 165 illuminates the fluid sample 150 deposited in the microfluidic channel formed by the recess 112 and the cover 120 with illumination 160. The illumination 160 is, for example, illumination for exciting fluorescence in the fluid sample 150. In one embodiment, the color sensing image sensor 100 includes the light source 165. In another embodiment, the color sensing image sensor 100 is configured to be inserted into a separate instrument that includes the light source 165. The light source 165 includes, for example, one or more light emitting diodes, one or more lasers and/or a white light source. The illumination 160 can be of a single wavelength range or light of different wavelengths/wavelength ranges can be applied sequentially. The cover 120 can be at least partially transmissive to the illumination 160.

In one embodiment, the color sensing image sensor is disposable, i.e., a single-use, device configured to be read by a separate, reusable instrument, which may include light source 165, processing module 142, and/or circuitry for outputting color image 146.

Optionally, the color sensing image sensor 100 may include a coating 111 on the recess 112 of the silicon substrate 110. The coating 111 is, for example, an anti-reflection coating that prevents image artifacts due to multiple reflections of light from the microfluidic channel associated with the recess 112. In one example, the coating 111 is an anti-reflection coating having a thickness in the range of 10 to 200 nm.

Without departing from the scope of the present invention, the color sensing image sensor 100 may include a plurality of recesses 112 that partially define a plurality of microfluidic channels. The cover 120 may include corresponding through holes 122 to provide fluid access to such a plurality of microfluidic channels. In addition, the recesses 112 may have a shape different from the example shown in Figure 1 without departing from the scope of the present invention. For example, the recesses 112 may extend beyond the plane of the cross-section shown in Figure 1. The recesses 112 may be non-linear, angular, and/or serpentine in shape. Such a shape can maximize the number of color pixel groups 118 in optical communication with the fluid sample 150.

FIG3 illustrates, in cross-sectional side view, an exemplary color sensing image sensor 300 with embedded microfluidics, which is an embodiment of color sensing image sensor 100 ( FIG1 ). Color sensing image sensor 300 includes a plurality of color pixel groups 318, each including photosensitive regions 314, 315, and 316. For clarity, FIG3 shows only the portion of color sensing image sensor 300 associated with one color pixel group 318. Photosensitive regions 314, 315, and 316 are embodiments of photosensitive regions 114, 115, and 116, respectively, and color pixel group 318 is an embodiment of one color pixel group 118.

Photosensitive regions 314, 315, and 316 span depth ranges 384, 385, and 386, respectively, relative to the surface of silicon substrate 110 associated with recess 112. Depth ranges 384, 385, and 386 do not overlap. Depth ranges 384, 384, and 386 correspond to the penetration depths of light 324, 325, and 326, respectively, into the microfluidic channel defined by recess 112 and lid 120. Light 324, 325, and 326 have non-overlapping wavelength ranges. In one exemplary embodiment, the wavelength ranges of light 324, 325, and 326 separate the visible light spectrum into red, green, and blue portions, such that color pixel group 318 generates three electronic signals that directly correspond to primary color information.

In one embodiment, color sensing image sensor 300 includes coating 350 on silicon substrate 110 in recess 112. Coating 350 is, for example, an anti-reflective coating. In one embodiment, cover 120 includes coating 360, which is, for example, a wavelength filter for filtering fluorescence excitation illumination, such as illumination 160.

In certain embodiments, silicon substrate 110 includes layer 340, which separates photosensitive regions 314, 315, and 316 from recess 112. Layer 340 absorbs light of wavelengths shorter than the wavelength of light 324. However, layer 340 is not photosensitive. Excessive p-type doping in layer 340 may render layer 340 light-insensitive. This p-type doping may annihilate any electrons generated in response to incident light in photosensitive regions 314, 315, and 316 before such electrons can migrate to one of these regions.

In one exemplary use scenario, color-sensing image sensor 300 is a fluorescence imaging device and light 324, 325, and 326 is fluorescence emission from fluid sample 150. In this case, color-sensing image sensor 300 can operate at a wavelength of fluorescence excitation illumination 332 that is shorter than the wavelength of light 324, 325, and 326, wherein layer 340 absorbs fluorescence excitation illumination 332, thereby acting as a fluorescence emission filter. Color-sensing image sensor 300 can also operate at a wavelength of fluorescence excitation illumination 332 that is longer than the wavelength of light 324, 325, and 326, such that photosensitive regions 314, 315, and 316 substantially transmit fluorescence excitation illumination 334, thereby eliminating or reducing the contribution of fluorescence excitation illumination 334 to the electronic signal generated by color pixel group 318. In this use scenario, light 324, 325, and 326 can be associated with different types of fluorescence, such that differentiation between light 324, 325, and 326 can distinguish between different types of sample components.

In another exemplary use case, color-sensing image sensor 300 is a fluorescence imaging device, wherein one of light sources 324, 325, and 326 is fluorescence excitation light, while the other two of light sources 324, 325, and 326 are fluorescence emissions from fluid sample 150. In such a use case, light sources 325 and 326 can be associated with different types of fluorescence, such that light sources 324, 325, and 326 can distinguish between fluorescence excitation and fluorescence emission, as well as between different types of sample components. Without departing from the scope of the present invention, color-sensing image sensor 300 may not include photosensitive region 116, and may distinguish between fluorescence excitation light and fluorescence emission by (a) using, for example, photosensitive region 114 to detect fluorescence excitation light and (b) using, for example, photosensitive region 115 to detect fluorescence emission.

FIG4 illustrates, in cross-sectional side view, another exemplary color sensing image sensor 400 with embedded microfluidics, which is an embodiment of color sensing image sensor 100 ( FIG1 ). Color sensing image sensor 400 is similar to color sensing image sensor 300 ( FIG3 ), except that color pixel group 318 is replaced by color pixel group 418. Color pixel group 418 includes photosensitive regions 414 , 415 , and 416 . Photosensitive regions 414 , 415 , and 416 are embodiments of photosensitive regions 114 , 115 , and 116 , respectively, and color pixel group 418 is an embodiment of color pixel group 118 .

Photosensitive regions 414, 415, and 416 span depth ranges 484, 485, and 486, respectively, relative to the surface of silicon substrate 110 associated with recess 112. Depth range 484 overlaps with depth range 485. Depth range 485 overlaps with depth range 486. However, depth range 484 does not overlap with depth range 486. In one exemplary implementation, the wavelength ranges of light 324, 325, and 326 separate the visible light spectrum into red, green, and blue portions, and depth ranges 484, 485, and 486 are such that (a) the blue intensity is the intensity measured by photosensitive region 414, (b) the green intensity is the intensity measured by photosensitive region 415 minus the blue intensity, and (c) the red intensity is the intensity measured by photosensitive region 416 minus the green intensity. In one embodiment, electronic circuit 130 includes logic gates 430 that perform these algebraic operations to generate primary color information of the electronic signals generated by photosensitive regions 414 , 415 , and 416 .

FIG5 illustrates, in cross-sectional side view, another exemplary color sensing image sensor 500 with embedded microfluidics, which is an embodiment of color sensing image sensor 100 ( FIG1 ). Color sensing image sensor 500 is similar to color sensing image sensor 400 ( FIG4 ), except that color pixel group 418 is replaced by color pixel group 518. Color pixel group 518 includes photosensitive regions 514 , 515 , and 516 . Photosensitive regions 514 , 515 , and 516 are embodiments of photosensitive regions 114 , 115 , and 116 , respectively, and color pixel group 518 is an embodiment of color pixel group 118 .

Photosensitive regions 514, 515, and 516 span depth ranges 584, 585, and 586, respectively, relative to the surface of silicon substrate 110 associated with recess 112. Depth ranges 584, 585, and 586 extend to substantially the same maximum depth relative to recess 112. In one embodiment, all of photosensitive regions 514, 515, and 516 are optimally located proximate to electronic circuitry 130 for facilitating transfer of electronic signals generated by photosensitive regions 514, 515, and 516 to electronic circuitry 130. Depth range 584 is greater than depth range 585, and depth range 585 is greater than depth range 586. In one exemplary embodiment, the wavelength ranges of light 324, 325, and 326 separate the visible spectrum into red, green, and blue portions, and the depth ranges 584, 585, and 586 are such that (a) the intensity of red is the intensity measured by photosensitive region 516, (b) the intensity of green is the intensity measured by photosensitive region 515 minus the intensity measured by photosensitive region 516, and (c) the intensity of blue is the intensity measured by photosensitive region 514 minus the intensity measured by photosensitive region 515. In one embodiment, electronic circuit 130 includes logic gates 530 that perform these algebraic operations to produce primary color information from the electronic signals generated by photosensitive regions 514, 515, and 516.

FIG6 is a diagram 600 illustrating an exemplary layout of color pixel groups of the color sensing image sensor ( FIG1 ), implemented with recess 622 and multiple color pixel groups 618. Color pixel group 618 is an embodiment of color pixel group 118. Color pixel group 618 includes photosensitive region 114, photosensitive region 115, and photosensitive region 116. Diagram 600 shows the outlines of photosensitive regions 114, 115, and 116 and recess 622 of silicon substrate 110, projected onto a plane orthogonal to the cross-section of FIG1 . For clarity, only one color pixel group 618 is labeled in FIG6 .

In the present embodiment of color sensing image sensor 100, photosensitive regions 114, 115, and 116 are arranged in separate rows that are cyclically repeated across color sensing image sensor 100. Photosensitive regions 114, 115, and 116 are, for example, (a) photosensitive regions 314, 315, and 315 of FIG. 3, (b) photosensitive regions 414, 415, and 415 of FIG. 4, or (c) photosensitive regions 514, 515, and 515 of FIG. 5.

Without departing from the scope of the present invention, this embodiment of color-sensing image sensor 100 may include fewer or more color pixel groups 618 than shown in FIG600. Recess 622 may have a different shape than shown in FIG600 and further include two or more separate recesses that, together with cover 120, define two or more separate microfluidic channels.

FIG7 illustrates another exemplary layout of color pixel groups of the color sensing image sensor ( FIG1 ), illustrated in diagram 700 , implemented with recess 722 and multiple color pixel groups 718 . Color pixel group 718 is an embodiment of color pixel group 118 . Color pixel group 718 includes two photosensitive regions 114 , one photosensitive region 115 , and one photosensitive region 116 . Diagram 700 shows the outlines of photosensitive regions 114 , 115 , and 116 and recess 722 of silicon substrate 110 , projected onto a plane orthogonal to the cross-section of FIG1 . For clarity, only one color pixel group 718 is labeled in FIG7 . Color pixel group 718 is configured in a two-by-two array with photosensitive regions 114 , 115 , and 116 .

FIG8 is another exemplary layout of color pixel groups of the color sensing image sensor ( FIG1 ), illustrated in diagram 800 , implemented with recess 722 and multiple color pixel groups 818. Color pixel group 818 is an embodiment of color pixel group 118. Color pixel group 718 includes a photosensitive region 114, a photosensitive region 115, a photosensitive region 116, and a photosensitive region 817. Photosensitive region 817 has a depth range relative to recess 722 that is different from the depth range of photosensitive regions 114, 115, and 116. Diagram 800 shows the outlines of photosensitive regions 114, 115, 116, and 817, and recess 722 of silicon substrate 110, projected onto a plane orthogonal to the cross-section of FIG1 . For clarity, only one color pixel group 818 is labeled in FIG8 . Color pixel group 718 is configured with photosensitive regions 114 , 115 , 116 , and 817 to form a 2 by 2 array.

In one embodiment A, photosensitive regions 114, 115, and 116 are photosensitive regions 314, 315, and 316, and photosensitive region 817 has a depth range spanning from a minimum to a maximum depth of photosensitive regions 314, 315, and 316. In one embodiment B, photosensitive regions 114, 115, and 116 are photosensitive regions 414, 415, and 416, and photosensitive region 817 has a depth range spanning from a minimum to a maximum depth of photosensitive regions 414, 415, and 416. In embodiments A and B, photosensitive regions 114, 115, and 116 can provide color information, while photosensitive region 817 provides monochrome luminance information.

FIG9A illustrates, in cross-sectional side view, the color sensing image sensor 100 ( FIG1 ), along with a lensless imaging of sample components 950 ( 1 ) and 950 ( 2 ) of a fluid sample. FIG9B shows a portion 100 ′ of the color sensing image sensor 100 including the sample component 950 ( 1 ). FIG9A and FIG9B are best viewed together. For clarity of illustration, the electrical connections 132 are not shown in FIG9A and 9B , and the optional coating 111 is not shown in FIG9A .

Silicon substrate 110 includes a light receiving surface 914 that receives light propagating from recess 112 toward color pixel group 118. In an embodiment including coating 111, light receiving surface 914 is an interface between coating 111 and a microfluidic channel defined by recess 112 and optional cover 120.

Optionally, silicon substrate 110 includes color pixel group 918 (similar to color pixel group 118 ) located in a portion that is not in optical communication with recess 112 . For clarity, not all color pixel groups 118 and 918 are labeled in FIG. 9A . In one example, color pixel group 918 is a dark pixel used to measure electronic noise associated with color pixel groups 118 and 918 . The electronic noise measured by color pixel group 918 can be subtracted from the electronic signal generated by color pixel group 118 to produce a noise-reduced color image 146 .

Sample components 950 (1) and 950 (2) generate light emissions 942 (1) and 942 (2), respectively. In one embodiment, sample components 950 (1) and 950 (2) are fluorescent markers and light emissions 942 (1) and 942 (2) are fluorescent emissions generated in response to fluorescence excitation illumination, such as illumination 160. In another embodiment, fluorescent emissions 942 (1) and 942 (2) are chemiluminescent emissions. In yet another embodiment, light emissions 942 (1) and 942 (2) are scattering of illumination 160 (1) on sample components 950 (1) and 950 (2), respectively. Without departing from the scope of the present invention, one or both of sample components 950 (1) and 950 (2) can be replaced by a sample process, such as a chemiluminescent reaction. Sample component 950 (3) of fluid sample 150 does not emit illumination. Therefore, sample component 950 (3) does not contribute to the electronic signal generated by color pixel group 118. In a fluorescence imaging scenario, sample component 950 (3) is, for example, a sample component that is not fluorescently labeled.

Silicon substrate 110 transmits at least a portion of emissions 942 (1) and 942 (2) to color pixel group 118. In a fluorescence imaging scenario, color pixel group 118 thereby detects at least a portion of the fluorescence emissions 942 (1) and 942 (2), thereby color pixel group 118 detects fluorescently labeled sample components 950 (1) and 950 (2). Thus, in the fluorescence imaging scenario, color pixel group 118 generates at least a portion of a fluorescence color image 146 representing fluorescently labeled sample components 950 (1) and 950 (2). In the chemiluminescence imaging scenario, color pixel group 118 detects at least some portion of the chemiluminescent emissions 942 (1) and 942 (2), thereby color pixel group 118 detects sample components (or processes) 950 (1) and 950 (2).

Cross-section 100' includes a sample component 950 (1). Each color pixel group 118 has an acceptance angle 919. For clarity of illustration, acceptance angle 919 is indicated for only a single color pixel group 118. Acceptance angle 919 represents the composite acceptance angle of the individual photosensitive regions in color pixel group 918. Therefore, acceptance angle 919 may be wavelength dependent. In one embodiment, acceptance angle 919 and distance 971 from light receiving surface 914 to color pixel 118 are such that only color pixel groups 118' proximate sample component 950 (1) are able to detect emission 942 (1) originating from sample component 950 (1). For color pixel group 118', line 943 outlines the portion of acceptance angle 919 that includes a line of sight to sample component 950 (1). Other color pixel groups 118 are not in the line of sight of sample component 950 (1), where sample component 950 (1) is within acceptance angle 919.

In one embodiment, the acceptance angle 919 and the distance 971 are such that only the color pixel groups 118 are positioned less than a distance away from the color pixel group 118, in a direction parallel to the light receiving surface 914, to detect emission from a sample component located at the light receiving surface 914. In this embodiment, the color pixel groups 118 together produce a color image 146, or portion of a sample component, at the light receiving surface 914 with minimal spatial blur. In another embodiment, the acceptance angle 919 and the distance 971 together result in a probability of overlapping fluorescence in the color image 146 of a fluid sample 150 containing a sample component of interest at a typical concentration being below a desired threshold. In yet another embodiment, the acceptance angle 919 is sufficiently small that the color image 146 of a fluid sample 150 containing evenly spaced sample components of interest at a typical concentration is overlap-free.

For imaging of fluid sample 150, where the sample components of interest do not necessarily settle onto light receiving surface 914, spatial blurring is minimized when depth 188 of recess 112 is small. Thus, in certain embodiments of color sensing image sensor 100, depth 188 is a minimum height that allows deposition of fluid sample 150 on the microfluidic channel defined by recess 112 and cover 120.

In one embodiment, depth 188 is less than 1 micron or less than 10 microns. Such a small value of depth 188 minimizes the required volume of fluid sample 150 and any associated analytical reagents. In another embodiment, depth 188 is greater than 10 microns, such as several hundred microns or millimeters in size.

In one embodiment, the lateral dimensions of color pixel group 118 are significantly smaller than the dimensions of the sample component of interest in the microfluidic channel associated with recess 112, where the lateral dimension of color pixel group 118 is defined as the largest dimension in a plane parallel to light receiving surface 914. This allows for accurate size and shape determination of the associated sample component and can further identify the associated sample component based on its size in color image 146. For example, the associated sample component can be a component of a detected event that further meets specified size and/or shape criteria.

FIG10 illustrates a color sensing image sensor 1000 having multi-layer microfluidics. Color sensing image sensor 1000 is an embodiment of color sensing image sensor 100 ( FIG1 ), including at least one external microfluidic channel in addition to the microfluidic channel(s) associated with recess(es) 112. Color sensing image sensor 1000 includes a cover 1020 that implements the at least one external microfluidic channel. Cover 1020 is an embodiment of cover 120 and includes a substrate 1030 and an undersubstrate 1040. Substrate 1030 is in contact with silicon substrate 110 and cooperates with recess(es) 112 to define microfluidics embedded in silicon substrate 110. Substrate 1030 includes at least one recess 1012. Substrate 1040 is in contact with substrate 1030, such that substrate 1040 and recess 1012 cooperate to define a microfluidic channel external to silicon substrate 110.

Substrates 1030 and 1040 have inlets and outlets formed through holes 1022 for the microfluidic channels defined by recess 1012. In addition, substrate 1040 has inlets and outlets formed through holes 1022 for the microfluidic channels defined by recess 1012(s) and substrate 1040.

Substrates 1030 and 1040 are, for example, glass and/or plastic substrates. Each recess 1012 includes at least one portion located above recess 112, i.e., offset from the recess in a direction perpendicular to recess 112, such that light propagating from the recess 1012 portion and light propagating from recess 112 toward photosensitive regions 114, 115, and/or 116 encounter the same path length to the photosensitive regions as previously discussed.

FIG11 illustrates an exemplary color sensing image sensor 1100 configured to reduce spectral blur. Color sensing image sensor 1100 is an embodiment of color sensing image sensor 100 ( FIG1 ). Color sensing image sensor 1100 includes a silicon substrate 1110, which is an embodiment of silicon substrate 110. Silicon substrate 1110 includes a plurality of negatively doped regions 1114 (doped n-type), a plurality of n-type doped regions 1115, and optionally, a plurality of n-type doped regions 1116. N-type doped regions 1114, 1115, and 1116 implement photosensitive regions 114, 115, and 116. N-type doped regions 1114, 1115, and 1116 may have depth ranges different from those shown in FIG11 without departing from the scope of the present invention. Furthermore, silicon substrate 1110 may include additional n-type doped regions having depth ranges different from those of n-type doped regions 1114, 1115, and 1116. Each n-type doped region 1114 and 1115 (and 1116, if included) is substantially surrounded by a positively doped (p-type doped) region 1120. The p-type doped region 1120 may have an extent different from that shown in FIG. 11 without departing from the scope of the present invention. For example, the p-type doped region 1120 may extend into the recess 112. For clarity of illustration, only one p-type doped region 1120 is labeled in FIG. 11.

The p-type doped region 1120 is capable of extinguishing any electrons generated in the p-type doped region 1120 in response to light incident thereon before such electrons can migrate to one of the n-type doped regions 1114 and 1115 (and 1116, if included). Thus, the p-type doped region 1120 can eliminate or reduce spectral blurring caused by photogenerated electron migration from portions of the silicon substrate 1110 outside of the considered n-type doped region to the corresponding n-type doped region 1114, 1115, or 1116.

Electrical connection 132 forms a cutoff at each p-type doped region 1120, and the p-type doped regions may have other openings. However, the extension of any p-type doped region adjacent to n-type doped region 1114, 1115, or 1116 reduces the likelihood of electron migration into the n-type doped region, thereby reducing the likelihood of spectral smearing.

Without departing from the scope of the present invention, regions 1114 , 1115 , and 1116 may be p-type doped regions and region 1120 may be n-type doped regions.

FIG12 illustrates an exemplary sample imaging system 1200 that utilizes a color sensing image sensor 1202 with embedded microfluidics to generate a color image 146 ( FIG1 ) of a fluid sample 150. Color sensing image sensor 1202 is an embodiment of color sensing image sensor 100, which includes cover 120. Sample imaging system 1200 includes color sensing image sensor 100 and processing module 142. Similar to the discussion of color sensing image sensor 100, with reference to FIG1 , processing module 142 may be incorporated into color sensing image sensor 1202.

In one embodiment, sample imaging system 1200 includes a control module 1210. Control module 1210 is communicatively coupled to electronic circuitry 130. Control module 1210 controls at least some functions of electronic circuitry 130. For example, control module 1210 controls the electronic circuitry to enable image capture by color-sensing image sensor 1202 of at least one fluid sample 150 deposited in (a) one or more embedded microfluidic channels associated with one or more recesses 112, and optionally (b) one or more external microfluidic channels associated with one or more recesses 1012 (FIG. 10). Control module 1210 may also output electronic signals controlled by electronic circuitry 130 to processing module 142.

In one embodiment, sample imaging system 1200 includes an analysis module 1220 that analyzes color image 146 to determine results 1222. Analysis module 1220 is communicatively coupled to processing module 142 and receives color image 146 therefrom. Analysis module 1220 is implemented, for example, as a computer or microprocessor. In such embodiments, analysis module 1220 includes: (a) machine-readable instructions 1224 encoded in non-transitory memory; and (b) a processor 1226 that executes machine-readable instructions 1224 on color image 146 to determine results 1222. Results 1222 include, for example, (a) a list of events detected in color image 146 and their color attributes, (b) the number and/or concentration of sample components of interest in fluid sample 150, and/or (c) a diagnostic result regarding the presence or absence of one or more sample components of interest in fluid sample 150.

In one embodiment, sample imaging system 1200 includes a fluidics module 1260 that controls, at least in part, fluid operations associated with fluid sample 150. Fluidics module 1260 may include one or more fluid pumps 1264 and/or one or more fluid valves 1266 to control such fluid operations. In one example, fluidics module 1260 deposits fluid sample 150 into a microfluidic channel associated with recess 112 or recess 1012, optionally using pump 1264. In another example, fluidics module 1260 opens valve 1266 to allow fluid sample 150 to flow into the microfluidic channel associated with recess 112 or recess 1012. In yet another example, fluidics module 1260 closes valve 1266 to prevent flow of fluid sample 150 into the microfluidic channel associated with recess 112 or recess 1012. In yet another example, fluidics module 1260 controls the delivery of additional assay reagents to the microfluidic channel associated with recess 112 or recess 1012.

Optionally, sample imaging system 1200 includes a light source 165. Optionally, light source 165 illuminates at least one microfluidic channel associated with well 112 or well 1012.

FIG13 illustrates an exemplary method 1300 for generating a color image of a fluid sample using a color sensing image sensor with embedded microfluidics. The color sensing image sensor 100 ( FIG1 ) can perform at least a portion of the method 1300. The sample imaging system 1200 ( FIG12 ) can also perform at least a portion of the method 1300.

Step 1310 performs lensless imaging of a fluid sample deposited in a microfluidic channel embedded in a silicon substrate onto a plurality of photosensitive regions of the silicon substrate. In one embodiment, method 1300 performs step 1312 to implement step 1310. In step 1312, method 1300 images photosensitive regions of the fluid sample at different depth ranges relative to the embedded microfluidic channel. The different depth ranges coincide with the penetration of light of different wavelength ranges.

In one example at 1312 , color sensing image sensor 100 images, without using an imaging objective lens, light received from fluid sample 150 deposited in a microfluidic channel associated with recess 112 onto photosensitive regions 114 and 115 (and optionally other photosensitive regions such as photosensitive region 116 ).

Step 1320 generates color information based on the penetration depth of light from the fluid sample deposited in the embedded microfluidic channel to the silicon substrate. In one embodiment, method 1300 performs step 1322 to implement step 1320. In step 1322, method 1300 provides position-sensing color information by generating electronic signals in response to light incident on the plurality of photosensitive regions in step 1310.

In an example of step 1322, each photosensitive region 114 and 115 (and optionally each photosensitive region such as photosensitive region 116) generates an electronic signal in response to light being absorbed by the photosensitive region and transmits the electronic signal to electronic circuit 130. Electronic circuit 130 processes the electronic signal to generate electronic signal 140.

In one embodiment, method 1300 includes depositing a fluid sample 150 in an embedded microfluidic channel 1302. In one embodiment of step 1302, a user deposits fluid sample 150 in a microfluidic channel associated with recess 112. In another embodiment of step 1302, fluidics module 1260 deposits fluid sample 150 in a microfluidic channel associated with recess 112.

In one embodiment, method 1300 includes a step 1330 of processing the position and color data generated by steps 1310 and 1320 to generate a color image. In one embodiment of step 1330, processing module 142 executes color calculator 144 on electronic signal 140 to generate color image 146.

Optionally, method 1300 includes step 1340, wherein the color information is used to distinguish different types of sample components or processes in the fluid sample deposited in the embedded microfluidic channel. In one example of step 1340, analysis module 1220 processes color image 146, as discussed with reference to FIG. 12, to generate an example of result 1222, which includes classifications of different components or processes of sample 150 based on the color information from color image 146.

The method 1300 can be extended to imaging multiple fluid samples using multiple microfluidic channels embedded in the same silicon substrate without departing from the scope of the present invention. Also, the method 1300 can be extended to imaging one or more fluid samples deposited in one or more external microfluidic channels, and multiple fluid samples deposited on embedded microfluidic channel(s), as discussed with reference to FIG. 10 , without departing from the scope of the present invention.

FIG14 illustrates an exemplary method 1400 for color fluorescence imaging of a fluid sample using a color-sensing image sensor with embedded microfluidics. Method 1400 is an embodiment of method 1300 ( FIG13 ). Color-sensing image sensor 100 ( FIG1 ) can perform at least a portion of method 1400. Sample imaging system 1200 ( FIG12 ) can perform at least a portion of method 1300. Method 1400 can be used to implement fluorescence measurements using a single fluorescent emission color or to implement composite fluorescence measurements using multiple different fluorescent emission colors.

Step 1410 performs lensless imaging of a fluorescently labeled fluid sample deposited in a microfluidic channel embedded in a silicon substrate onto a plurality of photosensitive regions of the silicon substrate. Step 1410 is an embodiment of step 1310 and includes steps 1412 and 1414.

In step 1412 , the fluorescently labeled fluid sample is illuminated with fluorescence excitation light. In one embodiment of step 1412 , light source 165 generates fluorescence excitation illumination, in one embodiment of illumination 160 , to illuminate a fluorescently labeled fluid sample 150 deposited in a microfluidic channel associated with recess 112 .

In step 1414, method 1400 performs step 1312 of method 1300 to image the fluorescent emissions sensed from the fluid sample in step 1412. An example of step 1414 is discussed with reference to color sensing image sensor 300 ( FIG. 3 ) and is applicable to color sensing image sensors 100 , 300 , 400 , 500 , 600 , 700 , 800 , 1000 , and 1100 of all of FIGs. 1 , 3 - 8 , 10 , and 11 .

Optionally, step 1410 includes step 1416 of filtering out the fluorescence excitation illumination. In step 1416, short-wavelength fluorescence excitation illumination is absorbed in a silicon layer between the microfluidic channel and the photosensitive region, and/or long-wavelength fluorescence excitation illumination is transmitted through the photosensitive region. Although not shown in FIG. 14 , step 1416 can filter out the fluorescence excitation illumination by detecting the fluorescence excitation illumination using photosensitive regions located at depth ranges different from the depth range associated with fluorescence emission. An example of step 1416 is discussed with reference to color sensing image sensor 300 and is applicable to all of color sensing image sensors 100, 300, 400, 500, 600, 700, 800, 1000, and 1100 of FIGS. 1 , 3 - 8 , 10 , and 11 .

In step 1420 , method 1400 performs step 1320 of method 1300 to generate color information based on the penetration depth of light into the silicon substrate, as discussed with reference to FIG. 13 .

Optionally, method 1400 includes step 1402 , wherein method 1400 performs step 1302 of method 1300 to deposit a fluorescently labeled fluid sample in the embedded microfluidic channel, as discussed with reference to FIG. 13 .

Method 1400 may further include step 1430 of performing step 1330 of method 1300 by processing the position and color data to generate a color image, as discussed with reference to FIG. 13 .

In one embodiment, method 1400 includes step 1440 of performing step 1340 of method 1300 to distinguish different types of fluorescence events. In one example of step 1440, method 1400 uses color data to distinguish different types of fluorescence emissions and, optionally, based thereon, to identify different types of sample components. Without departing from the scope of the present invention, step 1440 can use color data to distinguish between fluorescence excitation illumination and fluorescence emissions.

Method 1400 can be extended to fluorescence imaging of multiple fluorescently labeled fluid samples using multiple microfluidic channels embedded in the same silicon substrate without departing from the scope of the present invention. Also without departing from the scope of the present invention, method 1400 can be extended to imaging fluorescence from one of multiple fluorescently labeled fluid samples deposited in one or more external microfluidic channels, in addition to the fluorescently labeled fluid sample(s) being deposited in the embedded microfluidic channel(s), for example, as discussed with reference to FIG. 10 .

Figure 15 is a flow chart illustrating an exemplary wafer-level method 1500 for fabricating multiple color-sensing image sensors 100 (Figure 1) having embedded microfluidics. Figure 16 illustrates, in cross-sectional side view, the steps of method 1500. Figures 15 and 16 are best viewed together.

In step 1510, method 1500 processes one side of silicon wafer 1610, referred to as front side 1601, to produce a silicon wafer 1610'. Step 1510 includes a step 1512 of producing (a) a plurality of n-type doped regions 1614 located at a depth 1684 relative to plane 1690, (b) a plurality of n-type doped regions 1615 located at a depth 1685 relative to plane 1690, and, optionally, (c) a plurality of n-type doped regions 1616 located at a depth 1686 relative to plane 1690. N-type doped regions 1614, 1615, and 1616 implement photosensitive regions 114, 115, and 116. For clarity of illustration, not all n-type doped regions 1614, 1615, and 1616 are labeled in FIG. As discussed below, flat surface 1690 will become back side 1602 of silicon wafer 1610 in a subsequent step 1520 , where back side 1602 is the flat surface of silicon wafer 1610 facing away from front side 1601 .

As used herein, "silicon wafer" refers to a wafer based on silicon and/or silicon derivative(s). A "silicon wafer," as referred to herein, may include: (a) doping to locally alter the properties of the silicon or silicon source material; and (b) conductive substances, such as metals, to form electronic circuits.

Without departing from the scope of the present invention, depths 1684, 1685, and 1686 may be different than shown in FIG16, and silicon wafer 1610 may include a different number of n-type doped regions than shown in FIG16, including n-type doped regions located at depths different than those of n-type doped regions 1614, 1615, and 1616. Furthermore, the n-type doped regions may be arranged differently than shown in FIG16, for example, according to the layouts depicted in FIG6, 7, or 8.

In one embodiment, step 1510 further includes step 1514 of creating a p-type doped region that at least partially surrounds n-type doped regions 1614 and 1615, and optionally other n-type doped regions, such as n-type doped region 1616. This configuration is discussed with reference to FIG. 11 .

Step 1510 can perform steps 1512 and 1514 in any order, including simultaneously or with partial time overlap. In step 1510, one example of one or both of steps 1512 and 1514 is to be performed by ion implantation doping.

At step 1520, method 1500 processes backside 1602 of silicon wafer 1610'. Step 1520 includes step 1522 of creating recesses 1612 in plane 1690 to partially define microfluidic channels embedded in the silicon wafer. Each recess 1612 has a depth 1688 relative to plane 1690 such that (a) the mutually different depth ranges of step 1512 correspond to the depths of light of mutually different wavelength ranges penetrating from recess 1612 into silicon wafer 1610, and (b) the depth 1688 corresponds to the desired extent of the microfluidic channel in a dimension perpendicular to plane 1690. Step 1522 may create more recesses 1612 than shown in FIG. 16 without departing from the scope of the present invention.

Step 1522 may include steps 1524 and 1526. In step 1524, back side 1602 of silicon wafer 1610' is thinned to plane 1690, for example, using methods known in the art. Step 1524 produces silicon wafer 1610". In step 1526, material is removed from back side 1602 of silicon wafer 1610" to form recess 1612. Step 1526 may be performed using methods known in the art, such as etching. Step 1526 produces silicon wafer 1610'". Step 1526 may be performed before step 1524 without departing from the scope of the present invention.

In one embodiment, method 1500 includes step 1530, in which wafer 1620 is bonded to backside 1602 of silicon wafer 1610'' to form a wafer covering the plurality of recesses 1612. Step 1530 thereby creates a plurality of microfluidic channels defined by recesses 1612 and wafer 1620. Step 1530 can utilize bonding methods known in the art, including adhesive bonding (e.g., epoxy bonding), anodic bonding, direct bonding, and plasma-activated bonding. Wafer 1620 can include through-holes 1622 to form inlets and outlets for the microfluidic channels associated with recesses 1612. Alternatively, through-holes 1622 can be created in a subsequent step, not shown in Figures 15 and 16. Furthermore, wafer 1620 can include microfluidic channels, such as those associated with recesses 1012 (Figure 10).

In step 1540, silicon wafer 1610'', optionally combined with wafer 1620, is diced to produce a plurality of color sensing image sensors 100. Step 1540 may utilize methods known in the art.

15 and 16 , in embodiments of method 1500 that do not include step 1530 , cover 120 may be bonded to color sensing image sensor 100 in a subsequent step. In one scenario, a customized cover 120 is bonded to color sensing image sensor 100 to meet the needs of a specific user.

Combination of features

The features described above and with the following claims may be combined in various ways without departing from the scope of the invention. For example, it can be understood that a color sensing image sensor with embedded microfluidics, or associated methods, described herein, may be combined or interchanged with other color sensing image sensors with embedded microfluidics, or associated methods, described herein. The following examples illustrate some possible, non-limiting combinations of the above embodiments. It should be clear that many other changes and modifications may be made to the methods and apparatus described herein without departing from the spirit and scope of the invention. For example, the technical solutions of the present application may be summarized as follows:

(A1) A color sensing image sensor with embedded microfluidics may include a silicon substrate having (a) at least one recess partially defining at least one embedded microfluidic channel and (b) a plurality of photosensitive regions for generating position-sensing electronic signals in response to light from the at least one recess.

(A2) In the color sensing image sensor described in (A1), the at least two photosensitive regions may be located in at least two different depth ranges relative to the at least one recess to provide color information.

(A3) In the color sensing image sensor described in (A2), the at least two different depth ranges may respectively correspond to penetration depths of light in at least two different wavelength ranges.

(A4) In the color sensing image sensor described in (A2) to (A3), the multiple photosensitive regions can be arranged in multiple color pixel groups to generate color information for position sensing.

(A5) In the color sensing image sensor described in (A4), each color pixel group may include: (a) a first photosensitive region located within a first depth range relative to the at least one recess, wherein the first depth range is the same as a penetration depth of light in the first wavelength range, and (b) a second photosensitive region located within a second depth range relative to the at least one recess, wherein the second depth range is consistent with a penetration depth of light in a second wavelength range different from the first wavelength range.

(A6) In the color sensing image sensor described in (A5), each color pixel group may further include a third photosensitive region located in a third depth range relative to the at least one recess, wherein the third depth range coincides with a penetration depth of light in a third wavelength range that is different from the first wavelength range and the second wavelength range.

(A7) In the color sensing image sensor as described in (A6), the first, second and third depth ranges are such that the position sensing electronic signals together determine the primary color information.

(A8) In the color sensing image sensor described in (A7), the primary color information may be red, green, or blue color information.

(A9) In the color sensing image sensor described in (A7) to (A8), each photosensitive region can be a negatively doped silicon region.

(A10) In the color sensing image sensor described in (A9), each negatively doped region may be at least partially surrounded by a positively doped region to eliminate charge carriers generated by light near but outside the negatively doped region to reduce spectral smearing.

(A11) In the color sensing image sensor described in (A1) to (A11), it may further include a cover in contact with the silicon substrate, for cooperating with the silicon substrate to define at least one embedded microfluidic channel.

(A12) In the color sensing image sensor of (A11), the cover may include at least one external microfluidic channel, together with at least one embedded microfluidic channel, forming a multi-layer microfluidic network.

(A13) In the color-sensing image sensor of (A12), a portion of the cover associated with light propagation between the at least one external microfluidic channel and the plurality of photosensitive regions is substantially transparent to visible light.

(A14) In the color sensing image sensor as described in (A12) and (A13), at least a portion of the at least one external microfluidic channel may have the same lateral position as at least a portion of at least one recess therein, and multiple photosensitive areas are used to image the color sensitivity of the at least one external microfluidic channel, wherein the lateral position refers to the position dimension associated with the at least one recess parallel to the surface of the silicon substrate.

(A15) In the color sensing image sensor described in (A1) to (A14), the silicon substrate may include a silicon layer that is non-negatively doped and is located between the at least one recess and the plurality of absorbing photosensitive regions for fluorescence excitation, so as to excite fluorescence of a fluid sample disposed in the at least one recess.

(B1) A method for generating a color image of a fluid sample may include performing imaging of the fluid sample deposited in a microfluidic channel embedded in a silicon substrate, onto a plurality of photosensitive regions of the silicon substrate.

(B2) In the method described in (B1), the step of performing imaging may include performing lensless imaging of the fluid sample onto photosensitive areas of a plurality of silicon substrates located at a plurality of mutually different depth ranges relative to the microfluidic channel, wherein the mutually different depth ranges respectively correspond to penetration depths of light of mutually different wavelength ranges.

(B3) The method as described in (B1) and (B2) may further include generating color information based on the penetration depth of light into the silicon substrate.

(B4) In the method described in (B3), the step of generating color information may include generating electronic signals in response to light incident on the plurality of photosensitive areas to provide color information for position sensing.

(B5) The method of (B4) may further include processing the electronic signal to determine the color image.

(B6) In the method described in (B1) to (B5), the color image is a fluorescent image.

(B7) The method as described in (B6) may include absorbing the fluorescent excitation light incident on the silicon substrate in a silicon layer located between the microfluidic channel and at least a portion of the plurality of photosensitive regions in the silicon substrate.

(B8) The method of (B6) may substantially include transmitting the fluorescent excitation light incident in the plurality of photosensitive regions through the plurality of photosensitive regions.

(B9) The method described in (B1) to (B8) may further include performing lensless color imaging of a fluid sample deposited in a microfluidic channel located outside the silicon substrate via the microfluidic channel using the plurality of photosensitive regions.

(C1) A wafer-level method for fabricating multiple color sensing image sensors with embedded microfluidics may include: (a) processing the front side of a silicon wafer to produce multiple doped regions, wherein the doped regions are located at multiple different depth ranges relative to a plane of a back side of the silicon wafer, and (b) processing the back side to partially define multiple embedded microfluidic channels by fabricating recesses having depths relative to the plane of the back side, such that the different depth ranges correspond to different wavelength ranges of light penetration depths from the recesses to the silicon wafer.

(C2) The wafer-level method of (C1) may further include cutting the silicon substrate to thereby singulate the color-sensitive image sensors, wherein each color-sensitive image sensor includes at least one channel embedded in the microfluidic system.

(C3) In the wafer-level method described in (C1) and (C2), the step of processing the back surface may include thinning the back surface to define a plane of the back surface and etching a recess.

(C4) In the wafer-level method described in (C3), the thinning step may include thinning the back side by an amount such that the depth of the recess, relative to the plane of the back side, corresponds to the desired extent of the microfluidic channel in a dimension perpendicular to the plane of the back side.

(C5) The wafer-level method described in (C1) to (C4) may further include bonding a cover to the backside.

(C6) In the wafer-scale method described in (C5), the cover may include a plurality of external microfluidic channels.

(C7) In the wafer-level method of (C6), each of the plurality of external microfluidic channels can form a multi-layer microfluidic network together with at least one of the embedded microfluidic channels by imaging the doped region associated with a color sensing image sensor.

Changes may be made in the above-described apparatus and methods without departing from the scope of the present invention. It should therefore be noted that the matter contained in the above description and shown in the accompanying drawings is to be interpreted as illustrative and not restrictive. The appended claims are intended to cover the generic and specific features described herein, as well as all statements of the systems and methods of the present invention, which, as the language dictates, are within the scope thereof.

Claims (18)

1. A color sensing image sensor with embedded microfluidics, comprising: The silicon substrate includes: (a) at least one recess that partially defines at least one embedded microfluidic channel and (b) a plurality of photosensitive regions for generating a position-sensing electronic signal in response to light from the at least one recess; wherein at least two photosensitive regions are located at at least two different depth ranges relative to the at least one recess and have their own non-overlapping exposure areas in a direction perpendicular to the depth direction, thereby providing color information. The color sensing image sensor further includes a cover that contacts the silicon substrate, which serves to define at least one of the embedded microfluidic channels in conjunction with the silicon substrate; The cover includes at least one external microfluidic channel, which together with one of the embedded microfluidic channels forms a multi-layered microfluidic network, the multi-layered microfluidic network being imaged by multiple photosensitive areas. 2. The color sensing image sensor as claimed in claim 1, wherein the at least two different depth ranges respectively coincide with the penetration depth of light in at least two different wavelength ranges. 3. The color sensing image sensor as claimed in claim 1, wherein the plurality of photosensitive areas are disposed in a plurality of color pixel groups for generating color information for position sensing, and each color pixel group includes: A first photosensitive area, located within a first depth range relative to the at least one recess, coincides with the penetration depth of light within a first wavelength range; and The second photosensitive area is located within a second depth range relative to the at least one recess, which coincides with the penetration depth of light in a second wavelength range that is different from the first wavelength range. 4. The color sensing image sensor of claim 3, wherein each color pixel group further comprises a third photosensitive region located in a third depth range relative to the at least one recess and whose penetration depth coincides with that of light in a third wavelength range different from both the first wavelength range and the second wavelength range. 5. The color sensing image sensor of claim 4, wherein the first, second, and third depth ranges are configured such that the electronic signals sensed by the plurality of positions collectively specify the primary color. 6. The color sensing image sensor as described in claim 5, wherein the main color information is red, green and blue color information. 7. The color sensing image sensor as claimed in claim 1, wherein each photosensitive area is an n-type doped silicon region. 8. The color sensing image sensor of claim 7, wherein each n-type doped region is at least partially surrounded by a p-type doped region to eliminate charge carriers generated by the light that are close to but outside the n-type doped region, thereby reducing spectral blurring. 9. The color sensing image sensor of claim 1, wherein at least a portion of at least one of the external microfluidic channels having the same lateral position is at least a portion of the at least one recess, and the at least one of the external microfluidic channels is used for color sensing imaging by means of the plurality of photosensitive areas, wherein the lateral position refers to a position in dimension parallel to the surface of the silicon substrate associated with the at least one recess. 10. The color sensing image sensor of claim 1, wherein the silicon substrate includes a silicon layer that is not n-type doped and is located between the at least one recess and the plurality of photosensitive regions, for absorption of fluorescence excitation light in a fluid sample disposed in the at least one recess for exciting fluorescence. 11. A method for generating a color image of a fluid sample, comprising: Imaging a fluid sample to multiple photosensitive areas of a silicon substrate is performed, wherein the fluid sample is deposited in a microfluidic channel embedded in the silicon substrate, and at least two photosensitive areas have their own non-overlapping exposure areas in a direction perpendicular to the depth direction of the silicon substrate. Color information is generated based on the penetration depth of light into the silicon substrate; and Using the plurality of photosensitive areas, lensless color imaging is performed through the microfluidic channels of a fluid sample, wherein the fluid sample is deposited on an external microfluidic channel located outside the silicon substrate. 12. The method of claim 11, wherein The steps for performing lensless imaging include: Relative to the microfluidic channel, lensless imaging of the fluid sample is performed onto multiple photosensitive areas of the silicon substrate, the photosensitive areas being located at multiple different depth ranges, each of which coincides with the penetration depth of light of a different wavelength range; and The step of generating color information includes: providing color information for position sensing in response to an electronic signal generated in response to light incident on the plurality of photosensitive areas. 13. The method of claim 12, further comprising: The electronic signals are processed to determine the color image. 14. The method of claim 11, wherein the color image is a fluorescence image, and the method further comprises: The silicon layer absorbs the fluorescent excitation light incident on the silicon substrate, wherein the silicon layer is located in the silicon substrate and the silicon substrate is located between at least a portion of the microfluidic channel and the plurality of photosensitive regions. 15. The method of claim 11, wherein the color image is a fluorescence image, and the method further comprises: The fluorescence excitation light incident on one of the plurality of photosensitive regions is substantially transmitted, causing it to pass through the one of the plurality of photosensitive regions. 16. A wafer-level method for fabricating a plurality of color-sensing image sensors with embedded microfluidics, comprising: The front side of a silicon wafer is processed to generate multiple doped regions located at multiple different depths relative to the back side plane of the silicon wafer, wherein at least two doped regions have their own non-overlapping exposure areas in a direction perpendicular to the depth direction. The back surface is processed to partially define a plurality of embedded microfluidic channels, and in the plane of the back surface, by creating recesses having a depth relative to the plane of the back surface, the ranges of the plurality of different depths, from the recesses to the silicon wafer, respectively correspond to the penetration depth of light in different wavelength ranges. The silicon wafer is diced to thereby unify the color sensing image sensor, each of the color sensing image sensors including at least one of the embedded microfluidic channels; and An adhesive cap is attached to the back side, the cap including a plurality of external microfluidic channels, each of the plurality of external microfluidic channels together with at least one of the embedded microfluidic channels to form a multilayer microfluidic network, the multilayer microfluidic network being imaged by a doped region associated with one of the color sensing image sensors. 17. The method of claim 16, wherein the step of processing the back side comprises: Thinning the back surface to define the plane of the back surface; and The recess is etched. 18. The method of claim 17, wherein the thinning step comprises: thinning the back surface by a thickness relative to the plane of the back surface such that the depth of the recess corresponds to the degree required for a microfluidic channel in a dimension perpendicular to the plane of the back surface.