JP2005334067A - Multi-sensor with function to detect physical or chemical phenomenon of biological sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multisensor capable of grasping a physical phenomenon or a chemical phenomenon of a biological sample.
A multi-probe type sensor having a plurality of protrusions (probes) 2 on which a crystal is grown with a semiconductor substrate 1 as a base, and detects a physical or chemical phenomenon on the surface or inside of a biological sample. It has a function. Further, the physical phenomenon or chemical phenomenon to be detected is the potential of each part of the biological sample, and at least one amplification circuit / and signal processing circuit 3 is formed on the semiconductor substrate 1. . Further, the side surface 9 of the probe 2 is covered with an insulating layer, and the tip 8 is sharp.
[Selection] Figure 1

Description

  The present invention relates to a multisensor having a function of detecting a physical phenomenon or a chemical phenomenon of a biological sample, and specifically to a multisensor that detects a potential of a surface of a biological sample such as a cell or the inside thereof.

  In recent years, in various fields including the medical field, there is a demand for understanding various physical or chemical phenomena such as component concentration, temperature, pressure, flow rate, potential, reaction rate in biological samples such as cells and blood. On the other hand, there is an increasing demand for measurement in a fine region such as the inside of a cell.

In response to such a demand, for example, a multi-probe type sensor in which a probe and a signal processing circuit are integrated has been proposed. Specifically, as shown in FIG. 5, a probe 2 made up of a large number of needle-like protrusions and a signal processing circuit 3 for processing an electric signal input from each probe 2 are formed on the semiconductor substrate 1. There are multiple probes. This sensor includes an NMOSFET for each probe 2 as a switch array of the signal processing circuit 3. Each probe 2 is a protrusion which is crystal-grown using the drain (high concentration diffusion layer) of the NMOSFET as a base. Here, by using a VLS (Vapor-Liquid-Solid) method for forming the protrusions, the probe forming method is simpler than the conventional method, and the probe diameter and the interval between adjacent probes are smaller. (For example, refer to Patent Document 1).
JP 2000-333921 A

However, the conventional method for detecting a physical phenomenon or chemical phenomenon of a biological sample has the following problems, particularly in a fine region.
(1) There are many probes that are not suitable for measurement of a minute region with a large interval between probes, and even a fine needle-like probe such as a whisker can detect a plurality of probes in a stable arrangement at a predetermined interval. Sometimes it was difficult to do.
(2) In the conventional multi-probe, when all the probes are equal in length and there are cells divided into several layers like a biological sample, a three-dimensional site cannot be measured simultaneously. It was difficult to obtain accurate 3D information.
(3) The detection signal at each probe is very small, and in the case of a biological sample, since the living body has a potential itself that is a detection target, the stray capacitance existing around each probe and its induction It was in an environment that is susceptible to.
(4) The conventional probe has a large tip diameter, and it is difficult to directly measure even when information on a minute part of a biological sample is desired. In particular, regarding the measurement of the distribution of the potential inside the cell, it was very difficult to simultaneously measure a three-dimensional region together with the insertion into the cell.

  Accordingly, an object of the present invention is to provide a multisensor capable of grasping a physical phenomenon or a chemical phenomenon of a biological sample. Another object of the present invention is to provide a multi-sensor as means for enabling the imaging of a physical phenomenon or chemical phenomenon by quantifying such a physical phenomenon or chemical phenomenon and having high measurement accuracy and excellent responsiveness.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the multisensor shown below, and have completed the present invention.

  The present invention is a multi-probe type sensor having a plurality of protrusions (probes) grown on a semiconductor substrate as a base, and has a function of detecting a physical or chemical phenomenon on the surface or inside of a biological sample. It is characterized by having.

  That is, each probe constituting the multi-sensor has a detection function and can fix the positional relationship with each other, so that the physical or chemical phenomenon on the surface or inside of the biological sample can be grasped with high reproducibility. be able to. In addition, with a simple configuration that does not require position correction or other incidental means, it is possible to quantify physical phenomena or chemical phenomena with high accuracy and to achieve three-dimensional imaging of physical or chemical phenomena in biological samples. Can do.

  Further, the present invention provides the multisensor as described above, wherein the physical phenomenon or chemical phenomenon to be detected is a potential of each part of the biological sample, and at least one amplification circuit / and signal processing is provided on the semiconductor substrate. A circuit is formed.

  In biological samples, it is known that the potential possessed by living cells or even small spaces has a very close relationship with the activity of the living body, and the potential of each part of the biological sample, particularly the measurement of the potential distribution in a fine space, It is also very meaningful for analysis of the mechanism of biological samples. The multi-sensor according to the present invention is an effective means for such measurement because the functions may be concentrated in a very miniaturized portion called the probe tip. On the other hand, since the amount of signal from the tip is very small, when using the output from the multi-sensor, it is configured so as not to be affected as much as possible from outside (hereinafter referred to as “disturbance”). It is preferable. In the present invention, at least one amplification circuit / and signal processing circuit is formed on a semiconductor substrate, thereby converting a minute output from each probe into a pre-stabilized signal and transmitting the signal. By outputting, it is possible to obtain an output with high accuracy and stability with little influence of disturbance.

  Furthermore, the present invention is the multisensor as described above, wherein the side surface of the probe is covered with an insulating layer, and the tip is sharp.

  As mentioned above, the amount of signal from the tip of the probe is very small, and the elements of disturbance are large, and the detection signal itself is stabilized by eliminating the stray capacitance around each probe and the effects of its induction. It is necessary to plan. In particular, since the probe side surface has a large surface area, it is easily affected when the probe passes from the tip to the semiconductor substrate, and the stability of the minute signal can be improved by strengthening the seal with an insulating layer in this part. . Further, when it is used for detection in a very small region of a biological sample such as a cellular tissue, it is necessary to insert it through a gap or a diaphragm of the tissue. For such applications, as in the present invention, it is very advantageous to be a multi-sensor capable of sharply and firmly forming the tip. By configuring such a probe, it is possible to obtain an output with high accuracy and stability in combination with the early stabilization of the detection signal by the above-described preprocessing.

  As described above, by using the multi-sensor according to the present invention, it is possible to grasp a physical phenomenon or a chemical phenomenon for a biological sample and continuously obtain highly accurate three-dimensional information. In addition, the three-dimensional potential information inside the living body, which is also useful in analyzing the mechanism of the biological sample, can be obtained as a stable output with little influence of disturbances, and the information can be quantified. 3D imaging of physical or chemical phenomena can be achieved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 exemplifies a basic embodiment in which a multi-multi according to the present invention is used to make a target of a biological sample a cellular tissue. As shown in FIG. 1, the cell tissue 4 has a structure in which several types of tissue bodies 5 are sterically bonded. Each tissue body 5 has a different function, and it is necessary to accurately place the probe 2 at the location of each tissue body 5 when measuring the function. The multi-sensor of the present invention satisfies these requirements and can freely change the position and length of the probe 2 as necessary.

  A plurality of probes 2 formed of needle-like protrusions formed on a semiconductor substrate (silicon substrate) 1 are inserted into the cell tissue 4. In addition, an electronic circuit 3 connected to each probe 2 is configured on the semiconductor substrate 1, and a change in a physical phenomenon or a chemical phenomenon in the cell tissue 4 generated at the distal end portion of the probe 2 is, for example, a potential at the distal end portion of the probe 2. By taking out as a change, the change amount can be detected quantitatively. Examples of the physical phenomenon or chemical phenomenon to be targeted include potential, concentration, density, flow rate, temperature, magnetism, light, pressure, chemical reaction, polymer polymerization degree, and the like.

  In FIG. 1, the distal end portion of the probe 2 is in contact with each of the tissue bodies 5 forming the cell tissue 4 arranged in the cell culture membrane 6, and the physical phenomenon or chemistry for each tissue body 5. While detecting a change in phenomenon, it is possible to detect a change in a physical phenomenon or a chemical phenomenon as the entire cell tissue 4. This is the effect of the simultaneous measurement by the multi-sensor. In the case of a three-dimensional multi-sensor, a three-dimensional change of the cell tissue 4 can also be detected.

  FIG. 2 illustrates the overall configuration of such a multi-sensor. In the probe 2, a predetermined voltage is applied from the power supply unit 7 to the tip (sensing unit) 8 (may be applied to the side unit 9 in some cases), and the potential change of each sensing unit 8 at that time is detected. It can be taken out by the detection means 10 as a change in the current value, and the physical or chemical change of the object can be grasped.

  At this time, each probe 2 has a specific detection function due to the characteristics of its constituent material itself, like a potential detection probe, or by applying a predetermined process to the surface or inside of the probe 2, The side portion 9 can have a specific function with respect to a physical phenomenon or a chemical phenomenon. It is preferable that the heights of the probes are the same or several kinds of heights and are arranged at equal intervals. By fixing the position of the probe, it is possible to easily grasp the three-dimensional image of the cell tissue 4 that is the detection target, and to easily produce a three-dimensional image based on the output from each probe 2.

  Here, the probe 2 preferably has a function of detecting a potential of each part of the biological sample, particularly a potential in a fine space. For example, grasping the potential distribution in the cell tissue is also very significant for the analysis of the mechanism of the biological sample. In the multisensor according to the present invention, the potential detection function is provided at a very minimized portion such as the probe tip. This is an effective means for such measurement. Specifically, when an Au thin film layer is provided in order to fuse the two when forming the silicon-based probe 2 on the silicon substrate 1, an alloy portion made of an Au—Si alloy is provided at the tip portion 8. Therefore, it can be used as a detection end for potential detection as it is. Further, subsequent impurity diffusion can also be used depending on the purpose.

  Furthermore, it is also preferable to improve the detection sensitivity by applying a predetermined process to the probe 2. Specifically, when Pt or Ir is used as the metal at the tip, the contact resistance with silicon can be reduced, and the signal reading resolution can be improved. That is, the Au—Si alloy part at the tip 8 of the probe 2 is coated or supported with Au, Pt, Ir, or the like, thereby reducing the contact resistance with silicon and substantially improving the detection sensitivity. be able to.

The probe 2 is not limited to the case where only the distal end portion 8 has a specific function, but the side surface portion 9 of the probe can have a similar function or a different function. This is because the detection sensitivity may be improved by capturing the detection end as a line or a surface instead of a point. However, in the case of directly measuring the inside of the biological sample as in the present invention, it is preferable that the side surface portion 9 of the probe 2 is covered with the insulating layer 11 as illustrated in FIG. That is, for example, each tissue body 5 in the cell tissue 4 is independent, and the portion where the probe 2 is in contact with each tissue body 5 is a very small region, and is mainly only a part of the distal end portion 8 and the side surface portion 9. Rather, if the side surface portion 9 is also used as the detection end, it may be easily affected by other tissue bodies. Therefore, the stability of the minute signal at the tip 8 can be improved by covering the side surface 9 with the insulating layer 11 and strengthening the seal. As the insulating layer 11, in the case of the probe 2 based on silicon, the surface can be oxidized to form an insulator or protective film made of an oxide film (SiO ₂ ). By covering, not only the influence of the disturbance but also the contamination and deterioration of the probe 2 can be prevented and the like can be prevented.

  As the shape of the probe 2, it is possible to select any shape suitable for the purpose, such as a cylindrical shape or a tapered shape in which the outer diameter of the distal end portion 8 is reduced, or a reverse tapered shape thereof. In the case of directly measuring the inside, it is preferable that the tip 8 of the probe 2 is sharp as illustrated in FIG. The size of each cell body 5 is about several μm to several tens of μm □, and the probe 2 needs to be inserted into the gap or the surface and further into the inside, so that the tip 8 is sharp with 1 μm or less. It is preferable. When exceeding that, not only the insertion into the cell tissue 4 becomes difficult, but the tissue body 5 may be damaged. In particular, when measuring the inside of the biological sample with the probe 2, it is necessary to penetrate a wall portion separating the inside and the outside. However, if the wall portion is made of a soft material, it is difficult to penetrate. Therefore, by sharpening the tip 8, insertion into the biological sample can be facilitated, and when the probe 2 is pulled out, the wall can be kept in a state close to that before insertion. . Further, by forming a very miniaturized sensing portion at the tip 8 of the probe 2, even a minute region such as the inside of the tissue body 5 can be detected.

  As a method for producing the probe 2, not only the VLS method but also another liquid phase epitaxy method or a method of growing a crystal having a fine structure by using a gas phase epitaxy method or the like if the probe 2 has a low height. However, as a method for producing a multisensor applicable for the purpose of directly measuring the inside of a biological sample, a VLS method particularly suitable for producing a probe in a fine region is preferable.

  In the formation of the probe 2, the base on which the protrusion is crystal-grown may be a high-concentration diffusion layer of an element constituting the signal processing circuit of the sensor. -Emitter or collector of CMOS or bipolar transistor, n + layer or p + layer of diode, etc. It can also be formed in the gate circuit portion of the MOS transistor.

  Various electronic circuits 3 can be formed on the semiconductor substrate 1, but it is preferable to form at least one or more amplification circuits / and signal processing circuits on the probe 2. By converting the minute output from each probe into a pre-stabilized signal, and transmitting and outputting the signal, it is possible to obtain an output with high accuracy and stability with little disturbance influence. In particular, the formation of an impedance conversion circuit using an amplifier circuit (op-amp) is likely to cause various disturbances because the target object is physically or chemically fluctuated, such as measurement inside a biological sample, particularly a cell. It is very effective in the condition. In addition, the formation of the signal processing circuit can increase not only the stable output but also the independence of the multi-sensor, and the versatility of the configuration of the measuring apparatus such as wireless transmission.

  As described above, by using the multi-sensor according to the present invention, the characteristics of the biological sample that is the object can be detected as a three-dimensional physical phenomenon or chemical phenomenon. In addition, a physical or chemical phenomenon can be quantified to obtain a three-dimensional measurement image.

As described above, the present invention can be suitably used for measurement of cell functions and the like as described above, and can also be applied to the following fields.
(1) Application field as chemical microscope: ion concentration measurement / electrochemical field, gas distribution measurement field / two-dimensional dynamic observation and analysis of titration (2) environmental measurement / environment; application to bioremediation (3) Food inspection / food, microorganisms (4) ME field / medicine / ecological tissue; tissue cell surface and internal ion concentration measurement, cell surface and internal optical / potential measurement, DNA measurement (5) bio field (6) animal and plant field / Plant; callus surface and internal potential distribution measurement, organism, front view animal (7) Corrosion measurement field, metal; metal corrosion and coating, coating (8) surface analysis such as zeta potential, zeta potential of powder and ceramics.

  Moreover, the measurement object (sample) may be any of gas, liquid, solid, and powder, and the function of the biological sample that is the object is detected by detecting physical or chemical phenomena in various biological samples. It is useful for grasping typical characteristics.

Explanatory drawing which illustrates the embodiment of the multi sensor which concerns on this invention. Explanatory drawing which shows the whole structure of the multi sensor which concerns on this invention. Explanatory drawing which shows the detail of the multi sensor which concerns on this invention roughly. Explanatory drawing of the conventional multi sensor sensor.

Explanation of symbols

1 Semiconductor substrate (silicon substrate)
2 Probe 3 Signal processing circuit 4 Cell tissue 5 Tissue 6 Cell culture membrane 8 Tip 9 Side surface

Claims (3)

  A multi-probe type sensor having a plurality of protrusions (probes) grown on a semiconductor substrate as a base, and having a function of detecting a physical or chemical phenomenon on the surface or inside of a biological sample. Multi-sensor.   2. The physical phenomenon or chemical phenomenon to be detected is a potential of each part of the biological sample, and at least one amplification circuit / and signal processing circuit is formed on the semiconductor substrate. Multi-sensor. The multi-sensor according to claim 1, wherein the side surface of the probe is covered with an insulating layer and the tip is sharp.

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