CN111986831A - A fully enclosed disc optical trap device for repeated capture of microspheres by evanescent waves - Google Patents

Abstract

The invention discloses a totally enclosed wafer type evanescent wave device for repeatedly capturing microspheres. An upper cover glass is arranged on the glass substrate, and a cuboid capillary micro-cavity is arranged in the center of the glass substrate; a layer of plate glass with a higher refractive index and a layer of thin substrate with a lower refractive index are placed at the lower side in the cuboid capillary micro-cavity, and the plate glass and the thin substrate are tightly attached; the microcavity limits the motion range and the center of the optical trap of the particles, so that the particles can be captured conveniently, effectively, continuously, repeatedly and quickly, simultaneously, two beams of reversely transmitted laser are used for symmetrically irradiating the flat-bottomed glass to generate total reflection, coherent evanescent field standing waves are obtained, the heat effect of the total reflection evanescent field is enhanced, and the microspheres can be captured repeatedly. The invention can realize repeatable and rapid capture of particles, establishes evanescent field standing waves by utilizing double-beam total reflection, enhances the total-reflection evanescent field heat effect, improves the efficiency of repeatable capture of particles, and isolates external pollution and influence.

Description

A fully enclosed disc optical trap device for repeated capture of microspheres by evanescent waves

technical field

The invention relates to an on-chip integrated device in the field of micro-nano particle optical trap suspension, in particular to a fully enclosed disc type optical trap device for repeatedly capturing microspheres by evanescent waves.

Background technique

In the field of optical suspension, the particles to be captured usually adhere to the surface of the storage substrate. Therefore, in air and vacuum environments, the particles need to be detached from the surface of the substrate before entering the optical field to complete the capture. At present, there are three kinds of throwing schemes. The first two are the use of mechanical high-frequency vibration piezoelectric ceramics to separate the microspheres from the surface of the carrier and the use of ultrasonic atomization to throw the microspheres. The disadvantage of these two schemes is that a large number of microspheres need to be thrown in free space, the microspheres cannot be controlled to fall into the optical trap capture area accurately, the efficiency of microsphere capture is low, and the microspheres need to be continuously replenished, resulting in a large number of microspheres. waste, and the excess microspheres will also contaminate the interior of the vacuum chamber. There is also a recent proposal to heat the substrate with a pulsed laser to release the microspheres from the surface. However, due to the high energy and short pulse width of the pulsed laser, the microspheres will absorb a large amount of heat and expand in a short time, and the microspheres are easily destroyed. Therefore, the field of optical levitation measurement urgently needs a repeatable, high-accuracy and non-destructive starting method.

The optical trap system based on the traditional free-space optical path has a large volume, and the spatial optical path system is complex and has poor stability. Moreover, the sensing particles as the core sensitive unit only occupy a micrometer-sized area, and there is still a large amount of redundant space in the cavity. The existing way to recapture microspheres is to use pulsed laser to suspend the target microspheres repeatedly. However, since the target microspheres also absorb extremely high heat during the process of irradiating the substrate with pulsed light, the structure of the target microspheres is easily damaged.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the background art, the present invention provides a fully enclosed disc optical trap device for repeatedly capturing microspheres with evanescent waves. A repeatable, non-destructive and highly stable miniaturized optical trap suspension device can be realized.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

The invention includes a glass substrate and an upper cover glass, the upper cover glass is arranged on the glass substrate, a cuboid capillary microcavity is opened in the center of the glass substrate; and the lower refractive index thin substrate, the flat glass and the thin substrate are in close contact, and the bottom of the glass substrate close to the flat glass is provided with a downwardly inclined third fiber fixing port and a fourth fiber fixing port, and the third fiber is fixed The port and the fourth optical fiber fixing port are not parallel to each other and form an included angle, the third optical fiber fixing port and the fourth optical fiber fixing port are both connected to the cuboid capillary microcavity and are covered by flat glass and a thin substrate; the upper side of the cuboid capillary microcavity is symmetrical A third optical fiber fixed port and a fourth optical fiber fixed port are opened on both side walls of the glass base on both sides, the third optical fiber fixed port and the fourth optical fiber fixed port are coaxially arranged, and the third optical fiber fixed port and the fourth optical fiber fixed port are both connected to the cuboid capillary microcavity.

One or more microspheres are placed in the cuboid capillary microcavity, and the microspheres are attached to the thin substrate.

The first optical fiber and the second optical fiber are respectively connected to the first optical fiber fixed port and the second optical fiber fixed port, and two coaxial light beams are incident from the first optical fiber and the second optical fiber, and pass through the first optical fiber fixed port and the second optical fiber fixed port Coaxial incident into the cuboid capillary microcavity is aligned to form an optical trap.

The third optical fiber and the fourth optical fiber are respectively connected to the third optical fiber fixed port and the fourth optical fiber fixed port, and a beam of light is incident from the third optical fiber and the fourth optical fiber respectively, and is incident to the third optical fiber fixed port and the fourth optical fiber fixed port. Total reflection occurs at the junction of the flat glass and the thin substrate, resulting in evanescent waves that are transmitted to the thin substrate, and then exit from the fourth optical fiber fixed port and the third optical fiber fixed port respectively; The adjustment controls the microspheres close to the thin substrate to detach from the adhesion of the thin substrate and move to the optical trap of the cuboid capillary microcavity.

The upper cover glass covers the cuboid capillary microcavity, the first optical fiber fixed port, the second optical fiber fixed port, the third optical fiber fixed port and the fourth optical fiber fixed port, and the glass substrate and the upper cover glass are bonded to realize the cuboid capillary Sealing of the microcavity.

The glass substrate and the upper cover glass are engraved with a marking line indicating the center position, and the marking line indicating the center position of the glass substrate and the upper cover glass is adjusted so that the two are overlapped and sealed with UV glue.

The glass substrate is made of silicon or silicon dioxide.

Both the glass substrate and the upper cover glass are in the form of wafers.

The cuboid capillary microcavity adopts a silica capillary with a diameter of 6-9 microns, and the pore size is larger than the diameter of the microsphere.

The microspheres are metal materials, organic materials or dielectric materials.

The thickness of the thin substrate is not greater than the penetration depth of the evanescent wave.

The invention uses the micro-cavity to limit the movement range of the particles and the center of the optical trap, and realizes convenient and effective continuous and repeatable rapid capture of the particles. At the same time, the flat-bottom glass is symmetrically irradiated by two oppositely transmitted laser beams to generate total reflection, and a coherent evanescent field is obtained. wave, enhances the evanescent field thermal effect of total reflection, and greatly improves the efficiency of reproducible trapping of particles.

Beneficial effects of the present invention:

The invention uses the disc-type design to limit the movement range of the particles and the center of the optical trap, and generates total reflection by symmetrically irradiating the flat-bottom glass with two oppositely transmitted laser beams, obtaining coherent evanescent field standing waves, and enhancing the evanescent total reflection. The field effect avoids the influence of radiation pressure along the interface direction on the capture, achieves more stable capture, and improves the efficiency of capturing particles.

At the same time, the fully enclosed disc structure design of the present invention isolates external pollution and influence, and the optical trap system based on the optical fiber optical path is compact in structure and low in cost.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical trap device of the present invention.

FIG. 2 is a schematic structural diagram of a wafer-type glass substrate and an upper cover glass of the device of the present invention.

FIG. 3 shows the formation of a light trap trapping region when the first optical fiber and the second optical fiber are incident in opposite directions at the same time.

FIG. 4 is a schematic diagram of the microspheres from position A to position B after the laser light of the third optical fiber and the fourth optical fiber is incident.

FIG. 5 is a schematic structural diagram of the stable suspension of the microspheres after entering the optical trap capturing area.

In the figure: glass substrate 1, upper cover glass 2, four optical fiber fixing ports 3.1, 3.2, 7.1, 7.2, cuboid capillary microcavity 4, thin substrate 5, flat glass 6, microsphere 8.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments

As shown in FIG. 2 , the optical trap sensing substrate specifically implemented includes a glass substrate 1 and an upper cover glass 2, the upper cover glass 2 is arranged on the glass substrate 1, and the center of the glass substrate 1 is provided with a cuboid capillary microcavity 4; The glass substrate 1 on the upper side of the cuboid capillary microcavity 4 is provided with a first optical fiber fixing port 3.1 and a second optical fiber fixing port 3.2, and the glass substrate 1 on the lower side of the cuboid capillary microcavity 4 is provided with a third optical fiber fixing port 7.1 and a fourth optical fiber fixed port 7.2;

As shown in FIG. 2 , a layer of flat glass 6 with a higher refractive index and a thin substrate 5 with a lower refractive index are placed on the lower side of the cuboid capillary microcavity 4 , and the thin substrate 5 is closer to the cuboid capillary microcavity than the flat glass 6 In the center of the cavity 4, the flat glass 6 and the thin substrate 5 are in close contact, the flat glass 6 is in close contact with the inner side of the cuboid capillary microcavity 4, and the two sides of the bottom of the glass substrate 1 close to the flat glass 6 are provided with downwardly inclined third optical fibers for fixing The port 7.1 and the fourth optical fiber fixed port 7.2, the third optical fiber fixed port 7.1 and the fourth optical fiber fixed port 7.2 are not arranged parallel to each other at an included angle, and the third optical fiber fixed port 7.1 and the fourth optical fiber fixed port 7.2 are both connected to the cuboid capillary micropipette. The cavity 4 is covered by the flat glass 6 and the thin substrate 5; the two side walls of the glass substrate 1 on the symmetrical sides of the upper side of the cuboid capillary microcavity 4 are provided with a third fiber fixing port 7.1 and a fourth fiber fixing port 7.2, the third fiber The fixed port 7.1 and the fourth optical fiber fixed port 7.2 are coaxially arranged. The third optical fiber fixed port 7.1 and the fourth optical fiber fixed port 7.2 are both connected to the cuboid capillary microcavity 4 and are not covered by the flat glass 6 and the thin substrate 5 .

In the specific implementation, one or more microspheres 8 are placed in the cuboid capillary microcavity 4, and the microspheres 8 are attached to the thin substrate 5 or the cuboid capillary microcavity 4 located between the first optical fiber fixing port 3.1 and the second optical fiber fixing port 3.2 Central light trap location. One or more microspheres are fixed on the thin substrate 5 by adhesive force.

As shown in Figure 5, the first optical fiber and the second optical fiber are connected to the first optical fiber fixed port 3.1 and the second optical fiber fixed port 3.2 respectively, and two coaxial beams are incident from the first optical fiber and the second optical fiber, and pass through the first optical fiber. The fixed port 3.1 and the second optical fiber fixed port 3.2 are coaxially incident into the cuboid capillary microcavity 4 and aligned to form an optical trap. The optical trap will capture the close microspheres. If the microspheres are far away from the optical trap, the optical trap cannot capture the microspheres. The third fiber/fourth optical fiber is required to control the incident beam to make the microspheres close to the optical trap and then capture.

The first optical fiber and the second optical fiber are both welded and fixed with the optical fiber fixing port, and sealed with UV glue.

One end of the first optical fiber and the second optical fiber to form a double-beam optical trap is a self-focusing optical fiber, which can first diverge and then converge the captured light beam, and the focal point or beam waist of the captured light has a certain distance from the fiber end face. After alignment, the optical fiber distributes the first trapping beam and the second trapping beam to form a double-beam optical trap. The self-focusing fiber mainly includes three parts, which are single-mode fiber, coreless fiber and gradient index fiber in sequence.

The double-beam optical trap is close to the microspheres, and the lower edge of the optical trap region is several micrometers away from the surface of the microspheres close to the thin substrate 5 .

The third optical fiber and the fourth optical fiber are respectively connected to the third optical fiber fixed port 7.1 and the fourth optical fiber fixed port 7.2, respectively, a beam of light is incident from the third optical fiber and the fourth optical fiber, and is fixed by the first optical fiber fixed port 3.1 and the second optical fiber The port 3.2 is incident on the junction of the flat glass 6 and the thin substrate 5, and nearly total reflection occurs, and only the light beam with evanescent waves is irradiated to the thin substrate 5, and then exits from the second optical fiber fixed port 3.2 and the first optical fiber fixed port 3.1 respectively. ; Through the beam irradiation of the third optical fiber and the fourth optical fiber, the microspheres 8 closely attached to the thin substrate 5 are adjusted and controlled to break away from the adhesion of the thin substrate 5 and move to the optical trap of the cuboid capillary microcavity 4 .

The flat glass 6 and the thin substrate 5 are arranged in close contact and have a refractive index difference, the refractive index of the flat glass 6 is higher than the refractive index of the thin substrate 5, and the incident angles of the light beams of the third optical fiber and the fourth optical fiber are greater than the critical angle, Moreover, the capillary microcavity structure is used to limit the movement range of the particles and the trapping center of the optical trap. At the same time, two oppositely transmitted linearly polarized lights are symmetrically irradiated on the bottom surface of the flat-bottom glass to generate total reflection, and a coherent evanescent field standing wave beam is irradiated to the thin On the substrate 5, the evanescent field effect of total reflection is enhanced. At first, as shown in FIG. 3, the thin substrate 5 placed on the flat-bottomed glass absorbs the evanescent wave and expands due to heat, which generates an upward force and bounces the microspheres 8 located on the surface of the thin substrate 5, as shown in FIG. 4. As shown, the microsphere 8 gets the initial acceleration, rises to the trapping center of the optical trap, and is stably trapped and suspended by the optical trap.

After the stable suspension experiment of the microsphere 8 is completed, the two beams incident on the first optical fiber and the second optical fiber are turned off, the microsphere 8 is separated from the optical trap and returned to the surface of the thin substrate 5, and the thin substrate 5 waits for the next evanescent field standing wave Arrival control, so that the microspheres 8 are continuously and stably captured and suspended in the optical trap and attached to the thin substrate 5 in sequence, and the optical suspension test of the microspheres 8 is completed.

The third optical fiber and the fourth optical fiber are welded and fixed through the optical fiber fixing port, and sealed with UV glue. The third optical fiber and the fourth optical fiber are two single-mode optical fibers. The input light waves of the two optical fibers have the same frequency and opposite transmission directions, which avoids the influence of radiation pressure along the interface direction on the capture, isolates the influence of the outside world, and achieves better performance. Stable trapping with greater energy density, on the other hand, expands the range of action of the evanescent field.

The flat glass and the thin substrate 5 are symmetrically irradiated by two oppositely propagating laser beams to obtain coherent double beams, which enhances the evanescent field effect of total reflection.

The upper cover glass 2 covers the cuboid capillary microcavity 4, the first fiber fixing port 3.1, the second fiber fixing port 3.2, the third fiber fixing port 7.1 and the fourth fiber fixing port 7.2, the glass substrate 1 and the upper cover glass 2 Fitting realizes the sealing of the cuboid capillary microcavity 4, so that the cuboid capillary microcavity 4 only communicates with the four optical fiber fixing ports.

The specific implementation is to remove the space occupied by the flat glass and the thin substrate in the cuboid capillary microcavity. If the remaining aperture space is too large, it is difficult to constrain the range of the microspheres, and if it is too small, the assembly difficulty is increased. Generally, if the diameter of the microsphere is 1 micron, it is best to take three to five times the diameter of the microsphere.

The cuboid capillary microcavity adopts a silica capillary with a diameter of 6-9 microns, and the pore size is larger than the diameter of the microsphere. The cleanliness of the inner surface of the capillary tube should not exceed 0.1g per square meter of water in the inner cavity of the tube, and the internal oil content should not exceed 0.1g per square meter. The capillary can be vacuumed or filled with gas. The four fiber fixed ports are welded and spliced with the capillary, and sealed with UV glue to form a closed cuboid microcavity structure.

In a specific implementation, a marking line indicating the center position is engraved on the glass substrate 1 and the upper cover glass 2, and the marking line indicating the center position of the glass substrate and the upper cover glass is adjusted to overlap and seal with UV glue.

Both the glass substrate 1 and the upper cover glass 2 are in the form of wafers. The glass substrate 1 has a radius of 5 mm and a height of 2 mm, and is made of silicon or silicon dioxide.

The microspheres 8 are metal materials, organic materials or dielectric materials, which are captured by ordinary optical traps, and the size of the particles is in the order of nanometers to microparticles.

The thickness of the thin substrate 5 is not greater than the penetration depth of the evanescent wave. The material of the thin substrate 5 is a material with high expansion coefficient and low refractive index. The surface of the thin substrate is clean and free of impurities other than microspheres, which can be obtained by gas phase level or magnetron sputtering.

The plate glass 6 is made of titanium dioxide and barium oxide, and the refractive index is not less than 2.1.

Flat glass is glass with a high refractive index. Glass is an optically homogeneous medium, and the laser light from the third optical fiber and the fourth optical fiber can pass through uniformly.

The specific application embodiment situation of the present invention is as follows:

Step 1: The radius of the wafer glass substrate is 5mm, the height is 2mm, and the silicon material is selected. The upper cover glass has a radius of 5mm and a height of 0.1-0.3mm. Put the glass substrate and the upper cover glass in a container filled with clean water for cleaning, and blow dry with a compressed air gun after cleaning.

Step 2: The cuboid capillary microcavity is embedded in the glass substrate. The capillary microchamber stores one or more polystyrene microspheres. Use silica capillaries with a pore size of 6-9 microns, and the pore size is larger than the diameter of the microspheres. The cleanliness of the inner surface of the capillary in the capillary should not exceed 0.1g per square meter of water in the inner cavity of the tube, and the internal oil content should not exceed 0.1g per square meter. The capillary is filled with air.

Step 3: There are two optical fiber fixing ports on the upper end of the microcavity, and the first optical fiber and the second optical fiber are respectively placed. The first optical fiber and the second optical fiber are fixed by welding with the optical fiber fixing port, and sealed with UV glue. One end of the first optical fiber and the second optical fiber is a self-focusing optical fiber.

After being aligned, the first optical fiber and the second optical fiber respectively emit the first trapping beam and the second trapping beam to form a double-beam optical trap. The trapping area of the optical trap is obtained by the opposite transmission of two 980 nm laser beams. The lower edge of the trapping region of the light trap can be several micrometers away from the upper surface of the microsphere.

Step 4: A layer of flat glass with a high refractive index is placed in the cuboid capillary microcavity containing the particles, and a thin substrate with a low refractive index is placed on the flat glass. A microsphere 8 is placed on the thin substrate.

At this time, as shown in FIG. 3 , the microspheres 8 are far away from the optical trap and are not captured by the optical trap.

Step 6: The third optical fiber and the fourth optical fiber are welded and fixed through the optical fiber fixing port, and sealed with UV glue. After the four optical fibers are spliced with the cuboid capillary microcavity, they are sealed again with UV glue to form a closed cuboid capillary microcavity structure. The third optical fiber and the fourth optical fiber are two Gaussian single-mode optical fibers, and the light waves input by the two optical fibers have the same frequency, which are single-mode linearly polarized lasers of 1064 nanometers, and the transmission directions are opposite.

Step 7: While the first capture beam and the second capture beam are irradiated, as shown in Figure 4, the flat glass is irradiated symmetrically from the third optical fiber and the fourth optical fiber through two oppositely transmitted linearly polarized lights. The refractive index is greater than that of the thin substrate, and total reflection occurs at the junction of the flat glass and the thin substrate. The thin substrate absorbs evanescent waves, generates thermal expansion, and accelerates the microspheres on the surface of the thin substrate. The microspheres break away from the surface of the thin substrate by overcoming the adhesion force on the surface of the thin substrate, rise to the trapping area of the optical trap, close the two oppositely transmitted linearly polarized lights, and realize the stable suspension of the microspheres. The results are shown in Fig. 5.

Step 8: After the microspheres are separated from the trapping area of the optical trap, they fall back to the substrate, and repeat steps 3 to 6 to achieve repeated capture of the microspheres without replacing the microspheres.

It can be seen from the above implementation that the present invention has three advantages: the first is to use the microcavity to realize the repetition of the microspheres without loss of capture, and the second is to use the coherent evanescent field standing wave to enhance the evanescent field thermal effect of the total reflection. The third is that the optical trap system based on the optical fiber path has a compact structure, low cost, and high microsphere suspension efficiency, and has great development potential in miniaturization and commercialization.

The present invention provides a detailed introduction to the proposed fully enclosed disc optical trap device for repeated evanescent wave capture of microspheres. The above-mentioned specific embodiments are used to explain the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modifications and changes made to the present invention all fall into the protection scope of the present invention.

Claims (10)

1. A totally enclosed wafer type optical trap device for repeatedly capturing microspheres by evanescent waves is characterized in that:

the device comprises a glass substrate (1) and an upper cover glass (2), wherein the upper cover glass (2) is arranged on the glass substrate (1), and a cuboid capillary micro-cavity (4) is formed in the center of the glass substrate (1); a layer of plate glass (6) with a higher refractive index and a thin substrate (5) with a lower refractive index are placed at the lower side of the cuboid capillary micro-cavity (4), the plate glass (6) and the thin substrate (5) are tightly attached, a third optical fiber fixing port (7.1) and a fourth optical fiber fixing port (7.2) which are downward inclined are arranged at two sides of the bottom of the glass substrate (1) close to the plate glass (6), the third optical fiber fixing port (7.1) and the fourth optical fiber fixing port (7.2) are not parallel to each other and form an included angle, and the third optical fiber fixing port (7.1) and the fourth optical fiber fixing port (7.2) are both communicated with the cuboid capillary micro-cavity (4) and are covered by the plate glass (6) and the thin substrate (5); third optical fiber fixing ports (7.1) and fourth optical fiber fixing ports (7.2) are formed in two side walls of the glass substrate (1) on the two symmetrical sides of the upper side of the cuboid capillary micro-cavity (4), the third optical fiber fixing ports (7.1) and the fourth optical fiber fixing ports (7.2) are coaxially arranged, and the third optical fiber fixing ports (7.1) and the fourth optical fiber fixing ports (7.2) are communicated with the cuboid capillary micro-cavity (4).

2. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: one or more microspheres (8) are placed in the cuboid capillary micro-cavity (4), and the microspheres (8) are attached to the thin substrate (5).

3. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: the first optical fiber and the second optical fiber are respectively connected to the first optical fiber fixing port (3.1) and the second optical fiber fixing port (3.2), two coaxial light beams are incident from the first optical fiber and the second optical fiber, and are coaxially incident into the cuboid capillary micro-cavity (4) through the first optical fiber fixing port (3.1) and the second optical fiber fixing port (3.2) to be aligned to form a light trap.

4. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: the third optical fiber and the fourth optical fiber are respectively connected to a third optical fiber fixing port (7.1) and a fourth optical fiber fixing port (7.2), a beam is respectively incident from the third optical fiber and the fourth optical fiber, and is incident to the junction of the plate glass (6) and the thin substrate (5) through the third optical fiber fixing port (7.1) and the fourth optical fiber fixing port (7.2) to be totally reflected, evanescent waves are generated to be transmitted to the thin substrate (5), and then the evanescent waves are respectively emitted from the fourth optical fiber fixing port (7.2) and the third optical fiber fixing port (7.1); the microspheres (8) tightly attached to the thin substrate (5) are adjusted and controlled to be separated from the adhesion of the thin substrate (5) through the light beam irradiation of the third optical fiber and the fourth optical fiber and move to the light trap of the cuboid capillary micro-cavity (4).

5. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: the sealing structure is characterized in that the cuboid capillary micro-cavity (4), the first optical fiber fixing port (3.1), the second optical fiber fixing port (3.2), the third optical fiber fixing port (7.1) and the fourth optical fiber fixing port (7.2) are sealed by the upper cover glass (2), and the sealing of the cuboid capillary micro-cavity (4) is realized by the attachment of the glass substrate (1) and the upper cover glass (2).

6. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: marking lines for indicating the central positions are engraved on the glass substrate (1) and the upper cover glass (2), and the marking lines for indicating the central positions of the glass substrate and the upper cover glass are adjusted to be overlapped and sealed by UV glue.

7. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: the glass substrate (1) is made of silicon or silicon dioxide.

8. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: the glass substrate (1) and the upper cover glass (2) are both of a wafer structure.

9. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: the cuboid capillary micro-cavity adopts a silicon dioxide capillary with the diameter of 6-9 microns, and the aperture size is larger than the diameter of the microsphere.

10. The optical trapping device for repeatedly trapping microspheres by using the totally enclosed wafer-type evanescent wave as claimed in claim 1, wherein: the thickness of the thin substrate (5) is not more than the penetration depth of the evanescent wave.

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