Photoelectric tweezer chip and manufacturing method thereof

Abstract

The invention discloses a photoelectric tweezer chip and a manufacturing method thereof, according to the photoelectric tweezer chip, a photoconductive unit is arranged on a substrate, when a light beam irradiates the photoconductive unit, dielectrophoretic force can be excited and generated, and effective control over cells can be achieved. And the middle layer formed by the PEG material layer is arranged above the photoconductive unit, and the PEG material can protect the photoconductive unit and prevent adhesion of micro-objects. A plurality of nano columns distributed at intervals are arranged above the middle layer, and when a micro object is in contact with the nano columns, cell adhesion can be effectively avoided due to a small contact area; the dielectric constant difference between the nanorods and the solution can also form a concentrated electric field, repulsive force can be generated on micro-objects, and the cells are further prevented from being adhered to the photoelectric tweezers chip.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric tweezers chips, and in particular to a photoelectric tweezers chip and a method for manufacturing the photoelectric tweezers chip. Background Art

[0002] Currently, transistor-based photoelectric tweezers technology has been used to manipulate (e.g., select or move) micro-objects such as cells, bacteria, and microspheres. The typical structure of this type of photoelectric tweezers device is to set up a microfluidic channel between two upper and lower electrodes, where the upper electrode is usually a glass plate coated with indium tin oxide (ITO), and the lower electrode is a metal electrode with a phototransistor array on it to replace the ordinary photoelectric layer. When patterned light is irradiated on a specific area on the phototransistor array, the activated transistors allow current to pass, thereby forming a non-uniform electric field in the microfluidic channel, generating a dielectrophoresis (DEP) force that can manipulate cells.

[0003] Photoelectric tweezers technology uses photogenerated carriers to form virtual electrodes and manipulates micro-nanoparticles through dielectrophoretic force. Cells are prone to large-area adhesion on the surface of traditional photoelectric tweezers chips, resulting in uneven distribution of micro-objects, affecting the accuracy and repeatability of experimental results. Summary of the Invention

[0004] Based on this, it is necessary to provide a photoelectric tweezers chip to address the existing problems, including:

[0005] An upper electrode plate and a lower electrode plate, wherein a flow channel for solution to flow through is formed between the upper electrode plate and the lower electrode plate, the lower electrode plate comprises a base layer, an intermediate layer and a functional layer stacked in sequence, a photoconductive unit is provided on the top of the base layer, the intermediate layer is a PEG material layer arranged on the base layer, the PEG material layer covers the photoconductive unit, and the functional layer comprises a plurality of nanocolumns extending toward the upper electrode plate, wherein the plurality of nanocolumns are arranged at periodic intervals.

[0006] Preferably, the height of each of the nanopillars is in the range of 500 nm to 5 μm, and the distance between two adjacent nanopillars is smaller than the diameter of the micro-object.

[0007] Preferably, the size of each of the nanocolumns gradually decreases from the middle layer side to the upper electrode side.

[0008] Preferably, the absolute value of the difference between the dielectric constant of the nanorods and the dielectric constant of the solution is ≥20, and the photoelectric tweezers chip can exert a repulsive force on the object to be detected by adjusting the direction of the voltage.

[0009] Preferably, each of the nanorods is doped with a conductive material.

[0010] Preferably, the photoconductive material used in the photoconductive unit is an organic material or an inorganic material.

[0011] Preferably, each of the photoconductive units may be a photoconductive material coated on the substrate, or a semiconductor device made of a photoconductive material.

[0012] The present application also provides a method for manufacturing a photoelectric tweezers chip, comprising the following steps:

[0013] S01, providing a substrate, cleaning the surface, depositing a photoconductive material, and photolithography and etching to form a photoconductive unit;

[0014] S02, spreading PEG material on the substrate, heating, rinsing and drying to form an intermediate layer;

[0015] S03, providing a photoresist, spin-coating the photoresist on the intermediate layer, forming a nanocolumn array pattern by photolithography, and forming a functional layer of the nanocolumn array by etching and developing.

[0016] Compared with the prior art, the technical solution disclosed in the present invention has the following beneficial effects: a photoconductive unit is provided on the substrate, and when a light beam is irradiated on the photoconductive unit, a dielectrophoretic force is generated, thereby enabling effective manipulation of cells. An intermediate layer formed of a PEG material layer is then provided above the photoconductive unit. The PEG material can effectively protect the photoconductive unit and prevent micro-objects from adhering, effectively ensuring the uniformity of cells in the flow channel, and preventing the dielectrophoretic force generated by the photoconductive unit due to adhesion from being unable to effectively manipulate the micro-objects. A plurality of nanopillars are provided above the intermediate layer, and when micro-objects come into contact with the nanopillars, the smaller contact area effectively avoids cell adhesion. The difference in dielectric constant between the nanopillars and the solution can also form a concentrated electric field, which can generate a repulsive force on the micro-objects, further preventing cells from adhering to the photoelectric tweezers chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more complete understanding of the exemplary embodiments of the present invention can be obtained by referring to the following drawings. The drawings are intended to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present invention and do not constitute a limitation of the present invention. In the drawings, the same reference numerals generally represent the same components or steps.

[0018] Figure 1 A schematic diagram of a photoelectric tweezers chip according to an exemplary embodiment of the present application Figure 1 ;

[0019] Figure 2 A schematic diagram of a photoelectric tweezers chip according to an exemplary embodiment of the present application Figure 2 .

[0020] Reference numerals

[0021] 10-base layer; 20-photoconductive unit; 30-middle layer; 40-upper plate;

[0022] 50-nanometer pillars. DETAILED DESCRIPTION

[0023] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0024] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0026] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Example 1

[0028] See also Figure 1 or Figure 2, an embodiment of the present application provides a photoelectric tweezers chip for manipulating, sorting, and moving micro-objects, including cells, bacteria, and microspheres. The photoelectric tweezers chip includes an upper electrode plate 40 and a lower electrode plate. A flow channel for solution to flow through is formed between the upper electrode plate 40 and the lower electrode plate, and the micro-objects are manipulated in the solution. The lower electrode plate includes a base layer 10, an intermediate layer 30, and a functional layer stacked in sequence. A conductive layer, such as ITO glass, is provided on the top of the base layer 10, and a photoconductive unit 20 is provided above the ITO glass. The intermediate layer 30 is a PEG (polyethylene glycol) material layer provided on the base layer 10, and the PEG material layer covers the photoconductive unit 20. The functional layer includes a plurality of nanocolumns 50 extending toward the upper electrode plate 40, and the plurality of nanocolumns 50 are arranged at periodic intervals.

[0029] See also Figure 1 or Figure 2 The base layer 10 may be provided with a plurality of photoconductive units 20 with shorter widths, or a single photoconductive unit 20 with larger widths, as long as the dielectrophoretic force for propelling the micro-objects can be generated. The number, size and pattern of the photoconductive units 20 are not limited here.

[0030] The embodiments of the present application have the following beneficial effects: a conductive layer is provided on the substrate, and a photoconductive unit 20 is provided above the conductive layer. When a light beam is irradiated on the photoconductive unit 20, it can stimulate the generation of dielectrophoretic force, thereby enabling effective manipulation of cells. An intermediate layer 30 formed of a PEG material layer is then provided above the photoconductive unit 20. The PEG material can effectively protect the photoconductive unit 20 and prevent micro-objects from adhering, effectively ensuring the uniformity of cells in the flow channel, and preventing the dielectrophoretic force generated by the photoconductive unit 20 from adhering to micro-objects. A plurality of nanopillars 50 are provided above the intermediate layer 30. When micro-objects contact the nanopillars 50, due to the smaller contact area, cell adhesion can be effectively avoided. The difference in dielectric constant between the nanopillars 50 and the solution can also form a concentrated electric field, which can generate a repulsive force on micro-objects, further preventing cells from adhering to the photoelectric tweezers chip.

[0031] After adding the micro-objects, an alternating electric field can be applied to the nanopillars 50 region, using dielectrophoretic forces (DEP) to generate repulsive forces and reduce cell adhesion. Nanopillars 50 can be made of materials with dielectric constants significantly higher or lower than the solution (such as TiO2, Si3N4, or PDMS). This dielectric difference can be used to control the electric field distribution, concentrating the electric field in the nanopillars 50 region, thereby generating a repulsive force on cells. When the dielectric constant of the nanopillars 50 exceeds that of the solution, the electric field lines concentrate at the tips of the pillars, pushing cells away from areas of high gradient through negative dielectrophoresis (nDEP). For example, if the solution is a low-conductivity buffer (ε~80), using TiO2 nanopillars 50 (ε~100) can enhance the electric field concentration effect.

[0032] Perform electric field simulation to quantify the electric field gradient distribution around the nanopillars 50, and calculate the cell force using the dielectrophoresis force formula:

[0033]

[0034] Where Fcm is the Clausius-Mossotti factor, which is related to the dielectric constant of the cell and the solution, and εm is the dielectric constant of the solution. The gradient of the square of the electric field strength indicates the rate and direction of change of the electric field strength.

[0035] Specifically, a single photoconductive unit 20 can be made of any one of hydrogenated amorphous silicon (a-Si:H), titanium phthalocyanine (TiOPC), CulnSe2, cadmium sulfide (CdS), perovskite material, quantum dot material, etc. It can be a photoconductive material of a single material or a photoconductive material of a composite material. As long as the dielectrophoretic force can be generated by the photoconductive unit 20, no sole limitation is made here on the specific material and ratio of the photoconductive unit 20.

[0036] The photoconductive unit 20 can be disposed on the base layer 10 by coating, or by physical vapor deposition, chemical vapor deposition, solution deposition, atomic layer deposition, etc. The specific means of disposing the photoconductive unit 20 is not limited here.

[0037] Furthermore, in this embodiment, the height of each nanopillar 50 ranges from 500 nm to 5 μm, and the spacing between two adjacent nanopillars 50 is less than the diameter of the micro-object. The spacing between two nanopillars 50 is less than the diameter of the micro-object, which prevents the micro-object from becoming stuck between the two nanopillars 50. Furthermore, by setting the height of the nanopillar 50 to be greater than 500 nm, since the size of a micro-object is generally greater than 1 μm, when the upper edges of two adjacent nanopillars 50 just catch the diameter of the micro-object, the contact area between the micro-object and the PEG material layer of the photoelectric tweezers chip is also small, further preventing the micro-object from adhering to the PEG material layer. At the same time, the nanopillar 50 is tall enough to penetrate the electric field attenuation layer near the cell membrane, causing the micro-object to be pushed away.

[0038] Furthermore, in this embodiment, the size of each nanopillar 50 gradually decreases from the middle layer 30 side toward the upper electrode 40 side. Sharper nanopillars 50 (e.g., conical or needle-shaped) significantly enhance the local electric field gradient. Sharper nanopillars 50 also have a smaller contact area with the micro-object, resulting in less adhesion between the nanopillars 50 and the micro-object.

[0039] The material of the nanorod 50 can be photoresist, silicon dioxide, or silicon. Of course, when using photoresist to form the nanorod 50, it is necessary to use a photolithography process to form the nanorod 50 of the photoresist.

[0040] Furthermore, in this embodiment, the absolute difference between the dielectric constant of the nanopillars 50 and the dielectric constant of the solution is ≥20. The photoelectric tweezers chip can exert a repulsive force on the object being measured by adjusting the direction of the voltage. A large difference in the dielectric constant between the nanopillars 50 and the solution leads to a concentrated electric field, which can produce a repulsive force on micro-objects and precisely control their behavior.

[0041] Furthermore, in this embodiment, conductive material is doped into each nanorod 50. Doping with the conductive material can enhance the electric field intensity generated by the nanorod 50, thereby further repelling micro-objects.

[0042] Furthermore, in this embodiment, the photoconductive material used in the photoconductive units 20 is either an organic material or an inorganic material. Each photoconductive unit 20 can be a photoconductive material coated on a substrate, or a semiconductor device made of a photoconductive material. Preferably, each photoconductive unit 20 has a diode structure, a triode structure, or a heterojunction structure. When the photoconductive unit 20 has a triode structure, the photoconductive unit 20 has an NPN structure or a PNP structure. The specific structure of the photoconductive layer formed on the substrate of the lower plate is not specifically limited herein.

[0043] The difference in dielectric constant between the photoconductive unit 20 and the solution significantly alters the local distribution of the electric field. When the dielectric constant of the photoconductive layer (εcond) is higher than that of the solution (εliquid), the electric field in the illuminated area becomes more concentrated, forming a stronger electric field gradient, thereby enhancing the dielectrophoretic force (DEP). Therefore, a larger difference in dielectric constant between the photoconductive unit 20 and the solution can be used to enhance the DEP force.

[0044] Furthermore, in this embodiment, the photoconductive unit 20 is shaped like a rectangle, a circle, or an ellipse. Because the photoconductive unit 20 can induce an electric field through an optical pattern rather than relying directly on high-power laser focus, potential damage to biological samples caused by photothermal effects is significantly reduced, ensuring a more stable experimental environment.

[0045] Example 2

[0046] The present application also provides a method for manufacturing a photoelectric tweezers chip, comprising the following steps:

[0047] S01, providing a substrate, cleaning the surface, depositing a photoconductive material, and photolithography and etching to form a photoconductive unit 20;

[0048] S02, spreading PEG material on the top of the substrate, heating, washing and drying to form an intermediate layer 30;

[0049] S03 , providing a photoresist, spin-coating the photoresist on the intermediate layer 30 , photolithographically forming a nanorod array pattern, and forming a functional layer of the nanorod 50 array by etching and developing.

[0050] The photoelectric tweezers chip is manufactured using the aforementioned steps, with the PEG material layer forming the intermediate layer 30. The PEG material effectively protects the photoconductive unit 20 and prevents micro-object adhesion. A plurality of spaced nanopillars 50 are positioned above the intermediate layer 30. When micro-objects come into contact with the nanopillars 50, the reduced contact area effectively prevents cell adhesion.

[0051] Example 3

[0052] The present application also provides a method for manufacturing a photoelectric tweezers chip, comprising the following steps:

[0053] S01, providing a substrate, cleaning the surface, depositing a photoconductive material, and photolithography and etching to form a photoconductive unit 20;

[0054] S02, spreading PEG material on the top of the substrate, heating, washing and drying to form an intermediate layer 30;

[0055] S03, providing silicon dioxide, spin-coating photoresist on the intermediate layer 30, photolithographically forming a nanorod array pattern, and forming a functional layer of the nanorod array by physical etching, chemical etching or ion etching.

[0056] Alternatively, nanopillars can be formed by nanoimprinting followed by transfer to a sol-gel. Electron beam lithography or nanofabrication techniques are used to prepare an imprint template with a nanopillar array pattern on a silicon or quartz wafer. A sol-gel precursor solution of an organosilane compound (such as tetraethyl orthosilicate) is spin-coated onto the imprint template to form a uniform film. The imprint template coated with the sol-gel precursor is then pressed against the surface of a hydrogenated amorphous silicon chip, transferring the nanopillar pattern from the template to the sol-gel precursor film on the chip surface. A curing process is then performed to hydrolyze and condense the sol-gel precursor to form a silica nanopillar structure. The resulting photoelectric tweezers chip with a silica nanopillar array is then released from the mold.

[0057] Similarly, since the above steps are used to manufacture the photoelectric tweezers chip, the PEG material can prevent micro-objects from adhering, and when the nanopillars 50 and the micro-objects contact the nanopillars 50, the smaller contact area can effectively avoid cell adhesion.

[0058] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0059] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is at least two.

[0060] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0061] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A photoelectric tweezers chip comprising an upper plate and a lower plate, wherein a flow channel for a solution to flow is formed between the upper plate and the lower plate, characterized in that: The lower electrode plate includes a base layer, an intermediate layer and a functional layer stacked in sequence, a photoconductive unit is provided on the top of the base layer, the intermediate layer is a PEG material layer arranged on the base layer, the PEG material layer covers the photoconductive unit, and the functional layer includes a plurality of nanocolumns extending toward the upper electrode plate, and the plurality of nanocolumns are arranged at periodic intervals.

2. The photoelectric tweezers chip according to claim 1, wherein: The height of each nanocolumn is in the range of 500 nm to 5 μm, and the distance between two adjacent nanocolumns is smaller than the diameter of the micro-object.

3. The photoelectric tweezers chip according to claim 1, wherein: The size of each nanocolumn gradually decreases from the middle layer side to the upper electrode side.

4. The photoelectric tweezers chip according to claim 1, wherein: The absolute value of the difference between the dielectric constant of the nanorod and the dielectric constant of the solution is ≥20, and the photoelectric tweezers chip can exert a repulsive force on the object to be detected by adjusting the direction of the voltage.

5. The photoelectric tweezers chip according to claim 4, wherein: Each of the nanorods is doped with conductive material.

6. The photoelectric tweezers chip according to claim 1, wherein: The photoconductive material used in the photoconductive unit is an organic material or an inorganic material.

7. The photoelectric tweezers chip according to claim 1, wherein: Each of the photoconductive units may be a photoconductive material coated on the substrate, or a semiconductor device made of a photoconductive material.

8. A method for manufacturing a photoelectric tweezers chip, characterized in that: The following steps are involved: S01, providing a substrate, cleaning the surface, depositing a photoconductive material, and photolithography and etching to form a photoconductive unit; S02, spreading PEG material on the substrate, heating, rinsing and drying to form an intermediate layer; S03, providing a photoresist, spin-coating the photoresist on the intermediate layer, forming a nanocolumn array pattern by photolithography, and forming a functional layer of the nanocolumn array by etching and developing.

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