Transistor optical tweezers and microfluidic devices with increased light intensity

Abstract

This invention provides a transistor optical tweezers, comprising: a first electrode; a second electrode; and a phototransistor array disposed between the first and second electrodes. Each phototransistor is physically isolated from each other by a first insulating element. Each phototransistor includes a collector region, a base region, and an emitter region supported by a substrate. The emitter region of each phototransistor includes at least two sub-emitter regions, each sub-emitter region being at least partially physically isolated by the base region, and the at least two sub-emitter regions sharing a common base region and a collector region. This transistor structure achieves a larger photocurrent without changing the light intensity of the irradiated beam or the window size of the transistor, thereby enabling the generation of a larger DEP force. Furthermore, compared to an undivided emitter region, the presence of multiple sub-emitter regions results in a denser and more uniform distribution of the non-uniform electric field generated by illumination, thus facilitating the manipulation of micro-objects.

Description

Technical Field

[0001] The present invention relates to an optical tweezers device based on a phototransistor, and more particularly to a transistor optical tweezers device having increased light intensity and a microfluidic device comprising the transistor optical tweezers device. Background Technology

[0002] Transistor-based optical tweezers have been applied to manipulate (e.g., select or move) micro-objects such as cells and microspheres. A typical structure of this type of optical tweezers device involves a microfluidic channel between two electrodes. 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 instead of a conventional photoelectric layer. When patterned light shines on a specific area of ​​the phototransistor array, the activated transistors allow current to flow, creating a non-uniform electric field in the microfluidic channel and generating a dielectrophoretic (DEP) force capable of manipulating the micro-object.

[0003] The magnitude of the DEP force is limited by factors such as the volume of the controlled micro-object and the medium in which it is located. For a given test material, increasing the light intensity and / or the light-receiving area of ​​the phototransistor can result in a larger photocurrent, which is conducive to establishing a more significant non-uniform electric field, thereby generating a larger DEP manipulation force.

[0004] CN 107223074 B discloses a transistor optical tweezers and its microfluidic device. Each transistor structure includes a lateral transistor and a vertical transistor. In each transistor structure, a P-type base region surrounds an N-type emitter region, and an N-type collector region surrounds a P-type base region. Both the base region and the collector region include lateral and vertical portions. Compared to optical tweezers with only a vertical transistor, both lateral and vertical currents are generated simultaneously under the same light intensity. The additional lateral transistor is said to increase the intensity of the generated current, thereby allowing for more robust control of micro-objects.

[0005] However, the manufacturing process of this transistor structure is complex, especially the control of the lateral portion of the base region and collector region needs to be very precise, otherwise it is easy to cause the lateral current to not be generated normally, or even the entire transistor to fail to work properly.

[0006] In view of this, there is a need in the art for an improved optical tweezers device and a corresponding microfluidic device to overcome the above-mentioned deficiencies in the prior art. Summary of the Invention

[0007] One aspect of the present invention provides a transistor optical tweezers, comprising: a first electrode; a second electrode electrically connected to the first electrode; a phototransistor array disposed between the first electrode and the second electrode, the phototransistor array being composed of array-distributed phototransistors, each phototransistor being physically isolated from each other by a first insulating element, each phototransistor including a collector region, a base region, and an emitter region supported by a substrate; and a microfluidic channel disposed between the first electrode and the phototransistor array, wherein, for each phototransistor, its emitter region includes at least two sub-emitter regions, the sub-emitter regions being at least partially physically isolated by the base region, and the at least two sub-emitter regions having a common base region and a collector region.

[0008] In some embodiments, the base region includes a lateral portion and a longitudinal portion extending from the lateral portion to a first insulating element, the longitudinal portion including a first longitudinal portion extending from the lateral portion of the base region to a second insulating element and at least partially physically isolating the sub-emitting region. In some embodiments, at least one sub-emitting region is physically isolated by the lateral portion of the base region, the first longitudinal portion of the base region, and the first insulating element.

[0009] In some embodiments, the longitudinal portion includes a second longitudinal portion that abuts against and extends along at least one of the first insulating elements, the second longitudinal portion being spaced apart from the first longitudinal portion. In some embodiments, at least one sub-emitting region is physically isolated by a lateral portion of the base region, a first longitudinal portion of the base region, and a second longitudinal portion of the base region.

[0010] In some embodiments, the first longitudinal portion includes a plurality of mutually parallel and / or perpendicular first longitudinal portions. In some embodiments, at least one sub-emitting region is physically isolated only by the lateral portion of the base region and the first longitudinal portion of the base region.

[0011] In some implementations, each sub-emission region is surrounded by a base region but is at least partially exposed to the microfluidic channel.

[0012] In some embodiments, the first longitudinal portion has a first width, and the second longitudinal portion has a second width, the first width and the second width being independently from about 100 nm to about 1,000 nm. In some embodiments, the width of each of the first longitudinal portions is independently from about 100 nm to about 1,000 nm.

[0013] In some embodiments, each sub-emitter region includes a first doped region and a second doped region, wherein the doping concentration of the first doped region is higher than that of the second doped region. In some embodiments, the doping concentration of the first doped region is approximately 10. 18 cm-3 To about 10 21 cm -3 The doping concentration of the second doped region is approximately 10. 15 cm -3 To about 10 18 cm -3 .

[0014] In some embodiments, the emitter region of each phototransistor includes three, four, six, eight, or nine sub-emitter regions. In some embodiments, the emitter region of each phototransistor includes four sub-emitter regions. In some embodiments, each sub-emitter region has substantially equal volume. In some embodiments, each sub-emitter region has non-substantially equal volume.

[0015] In some implementations, the collector region of each phototransistor extends laterally to the first insulating element and has no longitudinal extension.

[0016] In some embodiments, each phototransistor is spaced apart by a pitch of about 5 micrometers to about 20 micrometers. In some embodiments, all sub-emitting regions of each phototransistor are separated by the pitch in an equal or non-equal manner.

[0017] In some embodiments, the first electrode is a glass plate coated with a conductive film. In some embodiments, the conductive film is an indium tin oxide (ITO) coating. In some embodiments, the second electrode is a metal electrode. In some embodiments, the metal electrode is a gold electrode.

[0018] In some embodiments, the microfluidic channel comprises a conductive medium containing cells. In some embodiments, the conductivity of the conductive medium is about 1 to about 10 mS / cm. In some embodiments, the conductive medium is a cell culture medium or a physiological solution. In some embodiments, the cell culture medium or physiological solution contains cells. In some embodiments, the cells are hybridoma cells.

[0019] Another aspect of the present invention provides a microfluidic device comprising any of the transistor optical tweezers described herein. In some embodiments, the microfluidic device further includes a control system, an optical patterning system, and an image acquisition system.

[0020] This invention provides a longitudinally extended portion of the base region. On one hand, the presence of this longitudinal extension brings the base region closer to the light beam, resulting in greater illumination intensity. Under the same illumination intensity, the base region of this invention can receive more photons compared to a base region without a longitudinal extension. On the other hand, the transmittance of the insulating capping layer is generally better than that of the emitter region covering the base region, thus allowing the longitudinal portion to receive even more photons. Therefore, this transistor structure achieves a larger photocurrent without changing the intensity of the illumination beam or the window size of the transistor, thereby generating a larger DEP force, facilitating the manipulation of micro-objects in microfluidic channels. Furthermore, compared to an undivided emitter region, the presence of multiple sub-emitter regions results in a denser and more uniform distribution of the non-uniform electric field generated by illumination, further enhancing the manipulation of micro-objects. Attached Figure Description

[0021] This invention will be described in more detail with reference to the accompanying drawings. It should be noted that the illustrated schemes are merely representative examples of embodiments of the invention, and to more clearly illustrate the details of exemplary embodiments, the elements in the drawings are not drawn to scale; the number of actual elements may vary, the relative positions of the actual elements remain substantially consistent with the illustrations, and some elements are not shown. In cases where multiple embodiments exist, when one or more features described in previous embodiments are also applicable to another embodiment, for the sake of brevity, these reusable features will not be repeated in subsequent embodiments. These subsequent embodiments should be understood as having described these reusable features, unless otherwise stated. Those skilled in the art will recognize upon reading this invention that one or more features shown in one figure can be combined with one or more features in another figure to construct one or more alternative embodiments not specifically shown in the drawings, and these alternative embodiments also constitute a part of this invention.

[0022] Figure 1A A partial cross-sectional view of an optical tweezers device according to an embodiment of the present invention is shown.

[0023] Figure 1B Showing Figure 1A A partial top view of the optical tweezers device shown.

[0024] Figure 1C This shows a partial perspective view of the transistor array.

[0025] Figure 1D A schematic diagram of a microfluidic device containing this optical tweezers device is shown.

[0026] Figure 2A shows a partial cross-sectional view of the transistor array of an optical tweezers device according to another embodiment of the present invention.

[0027] Figure 2B show Figure 2A A partial top view of the transistor array shown.

[0028] Figure 3 A partial cross-sectional view of a transistor array of an optical tweezers device according to another embodiment of the present invention is shown.

[0029] Figure 4 A partial cross-sectional view of a transistor array of an optical tweezers device according to another embodiment of the present invention is shown.

[0030] Figure 5 A flowchart illustrating a method for manufacturing a transistor array according to an embodiment of the present invention is shown.

[0031] The meanings of the reference numerals in the accompanying drawings are summarized as follows: Reference numerals with the same numbers represent the same elements. When applicable, a letter is added after the number to indicate repeated arrangements of the same element. For example, reference numerals 108a, 108b, 108c, and 108d represent four repetitions of element 108. 102, 202, 302, 402 - First doped region; 104, 204, 304, 404 - Second doped region; 105, 205, 305 - Emitter region; 106, 206, 306, 406 - Base region; 108, 208, 308, 408 - Collector region; 110, 210, 310, 410 - Substrate; 112, 212, 312, 412 - Insulating capping layer; 114 - Conductive plating layer; 116 - Second electrode; 118 - Cell; 120, 220, 320, 420 - First insulating element; 122 - Microfluidic channel; 124 - First electrode; 126 - Phototransistor; 128 - First electrode plate; 140, 240, 340, 440 - Second insulating element; 142, 242, 342, 442 - First longitudinal section; 144, 146, 244, 246 - Second longitudinal section; 150, 250, 350, 450 - Lateral section; 148, 248, 348, 448 - Insulating barrier; 130 - Optical pattern generating device; 132 - Image acquisition device; 134 - Computer system; 136 - Microfluidic device; 138 - Control system. W, L indicate dimensions. N+, N-, P indicate doping type and doping level. x, y, z indicate coordinates. Detailed Implementation

[0032] The exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the scope of the present invention is not limited to the disclosed embodiments. Those skilled in the art, after reading the disclosure of this invention, can modify and vary these exemplary embodiments based on the teachings of the present invention, without any inventive effort. Such modifications and variations are intended to be included within the scope outlined in the appended claims.

[0033] Figure 1A A partial cross-sectional view of an optical tweezers device according to an embodiment of the present invention is schematically shown. The optical tweezers device includes a first electrode 124 made of glass 128 coated with an indium tin oxide (ITO) conductive layer 114 and a second electrode 116 electrically connected to the first electrode 124, with an alternating current (AC) applied between the two electrodes. The AC current can be a square waveform, a sine waveform, or a triangular waveform. The first electrode 124 can also be other suitable ITO glass alternatives known in the art, such as AZO or GZO glass. In this embodiment, the second electrode 116 is a metal electrode. Suitable metal electrodes include noble metals such as gold, silver, platinum, palladium, and iridium; metals such as copper, tin, antimony, iron, cobalt, nickel, chromium, titanium, and manganese; or alloys such as platinum-barium, palladium-barium, iridium-tungsten-rhenium, and iridium-barium-osmium. In this embodiment, the second electrode 116 is a gold electrode.

[0034] An array of transistor structures is disposed above the second electrode 116 and electrically connected to the second electrode 116. A microfluidic channel 122 is disposed between the upper surface of the transistor array and the lower surface of the conductive plating layer 114 of the first electrode 124. The microfluidic channel 122 is generally composed of multiple microchannels connected in series or in parallel. Each microchannel contains multiple addressable micropores in which cells or other micro-objects can be located. The microfluidic channel 122 includes fluid inlets and outlets (not shown) to communicate with external fluids. Microfluidics (such as cell culture medium or physiological fluids) containing cells 118 (illustrated as cells 118a, 118b, 118c, and 118d, such as hybridoma cells that can secrete antibodies) flow into the microfluidic channel 122 through the inlet, flow through the microfluidic channel 122 in the direction shown by arrow A, undergo processing and manipulation (including photoelectric detection, culture, screening, movement, etc.), and finally flow out from the outlet, realizing the operation program of the microfluidic chip. Microfluidic channels 122 are typically made of polymeric materials such as PMMA, PC, PS, PP, PE, PDMS, etc., or are formed using photocuring agents. The height of microfluidic channels 122 is typically in the micrometer range, for example, 20 to 50 micrometers.

[0035] An array-type transistor structure includes multiple transistors 126 arranged in an array. A first insulating element 120 physically separates each transistor 126, thereby achieving electrical insulation between the individual transistors 126. The figure shows three transistors 126 physically separated by two identical first insulating elements 120a and 120b. Each first insulating element 120a and 120b is composed of insulating capping layers 112a and 112b and insulating barriers 148a and 148b (e.g., both made of SiO2 material). The insulating capping layers 112a and 112b are located on the surface of the transistors 126, and the insulating barriers 148a and 148b extend downwards from the insulating capping layers 112a and 112b to the substrate layer 110 of the transistors 126. Each transistor 126 can be a phototransistor 126.

[0036] The array of transistors 126 can be regular or irregular, but is preferably regular, for example, each transistor 126 is evenly spaced in the form of cubes or cuboids. When the array of transistors 126 is a regular arrangement of transistors 126, adjacent transistors 126 are spaced apart by a distance L, also known as a pixel period, which is the distance between the longitudinal central axes of adjacent insulating barriers 148a and 148b. In this embodiment, L is about 5 to about 20 micrometers. The longitudinal depth of the insulating barrier 148 is greater than the sum of the thicknesses of the emitter region 105, the base region 106, and the collector region of transistor 126, for example, about 10% to about 30% of the sum of said thicknesses. For example, the longitudinal depth of the insulating barrier 148 can be about 2 to about 10 micrometers. The width of the insulating barrier 148 can be about 100 nm to about 2,000 nm. The portion of transistor 126 not covered by the insulating capping layer 112 is called a window, and the size of the window is about 1 to about 20 micrometers. As described below, in this invention, the window is divided into a corresponding number of sub-windows by the sub-emission area, either uniformly or non-uniformly.

[0037] Transistor 126 includes a substrate layer 110, a collector region 108 disposed on the substrate layer, a base region 106 disposed on the collector region 108, and an emitter region 105 disposed on the base region 106. The substrate layer 110 is located at the bottom of transistor 126 and is directly electrically connected to a second electrode 116. In this embodiment, the substrate layer 110 contains an N-type dopant. The substrate layer 110 can be a heavily doped region. For example, the doping concentration of the substrate layer 110 is approximately 10. 18 cm -3 To about 10 21 cm -3 The thickness of the substrate 110 can be a suitable thickness generally accepted in the art. For example, the thickness of the substrate 110 is typically greater than 50 micrometers, such as about 50 to about 500 micrometers. The substrate 110 may have a resistivity of about 0.001 to about 0.05 ohm-cm.

[0038] The collector region 108 extends laterally to the insulating barrier 148 and abuts against adjacent insulating barriers 148a and 148b at its two ends, respectively. The collector region 108 is disposed on the side of the substrate layer 110 opposite to the second electrode 116. The collector region 108 may be N-type doped. Relative to the substrate layer 110, the collector region 108 may be a lightly doped region. For example, the doping concentration of the collector region 108 is approximately 10⁻⁶. 15 cm -3 To about 10 18 cm -3 The thickness of the collector region 108 can be from about 100 nm to about 15,000 nm, for example from about 500 nm to about 3,000 nm.

[0039] It is important to note that, unless otherwise stated, the terms "heavily doped region" and "lightly doped region" and their corresponding symbols are used in this invention only in their relative sense; that is, when the doping concentration of one doped region is higher than that of another, the region with the higher doping concentration is called the heavily doped region, and the region with the lower doping concentration is called the lightly doped region, and there is no necessary connection with the absolute value of their actual doping concentration. N-type dopants can be from any source of electrons. Suitable examples of N or N+ dopants include phosphorus, arsenic, antimony, etc. P-type dopants can be from any source of holes. Suitable examples of P or P+ dopants include boron, aluminum, beryllium, zinc, cadmium, indium, etc.

[0040] The base region 106 is disposed on the side of the collector region 108 opposite to the substrate layer 110. In this embodiment, the base region 106 contains a p-type dopant. A suitable doping concentration can be approximately 10⁻⁶. 16 cm -3 To about 10 18 cm -3 The base region 106 has a suitable thickness, for example, from about 100 nm to about 3,000 nm.

[0041] The emitter region 105 is located on the side of the base region 106 opposite to the collector region. The upper surface of the emitter region 105 forms the upper surface of the transistor 126 and is exposed to the microfluidic channel 122, opposite to the ITO conductive plating layer 114 of the first electrode 124. The lower surface of the substrate layer 110 forms the lower surface of the transistor 126 and is electrically connected to the second electrode 116. When a patterned light beam shines on the transistor 126, the beam penetrates the emitter region 105 and reaches the base region 106, generating a photoelectric effect and turning on the transistor 126.

[0042] In this embodiment, the emitter region 105 includes a first doped region 102 and a second doped region 104, wherein the second doped region 104 is adjacent to the base region 106, the first doped region 102 is disposed above the second doped region 104, and at least a portion of the first doped region 102 directly faces the ITO conductive plating layer 114 of the first electrode 124. An insulating capping layer 112 at least partially covers the first doped region 102. The first doped region 102 and the second doped region 104 each extend laterally and parallel to adjacent insulating barriers 148a and 148b. The first doped region 102 and the second doped region 104 have the same doping type, and the first doped region 102 has a higher doping concentration than the second doped region 104. For example, both the first doped region 102 and the second doped region 104 contain an N-type dopant, the first doped region 102 is a heavily doped region N+, and the second doped region 104 is a lightly doped region N-. When both the first doped region 102 and the second doped region 104 contain P-type dopant, the first doped region 102 is a heavily doped region (P+), while the second doped region 104 is a lightly doped region (P-). The doping concentration of the first doped region 102 can be approximately 10 to approximately 10 of the doping concentration of the second doped region 104. 6 For example, the doping concentration of the first doped region 102 can be approximately 10 times that of the second doped region 104. 2 To about 10 5 times, or about 10 3 The doping concentration of the first doped region 102 can be approximately 10 times. 18 cm -3 To about 10 21 cm -3 The doping concentration of the second doped region 104 can be approximately 10. 15 cm -3 To about 10 18 cm -3 .

[0043] In this document, the terms horizontal, vertical, and longitudinal correspond to the y, z, and x directions in the xyz coordinate system shown in Figure 1, respectively. The terms horizontal, vertical, and longitudinal are used only in their relative sense and for convenience of expression; that is, an element described as horizontal can also be described as longitudinal or longitudinal, and correspondingly, an element described as longitudinal and longitudinal is described as horizontal, and so on.

[0044] In this embodiment, the base region 106 includes a lateral portion 150 that extends laterally to and abuts against adjacent insulating barriers 148a and 148b. The base region 106 also includes longitudinal portions 142, 144, and 146 extending from the lateral portion 150. The longitudinal portions 142, 144, and 146 include a first longitudinal portion 142 that extends from the lateral portion 150 to a second insulating element 140. The second insulating element 140 and the first insulating element 120 may be made of the same or different electrically insulating materials, for example, both made of SiO2. The second insulating element 140 completely covers the first longitudinal portion 142 and at least partially covers the first doped region 102. The second insulating element 140 isolates the emitter regions 105a and 105b on the surface of the transistor 126 exposed to the microfluidic channel 122. The thickness of the first longitudinal portion 142 is substantially equal to the thickness of the emitter region 105, for example, it may be from about 500 nm to about 4,000 nm.

[0045] In this embodiment, the base region 106 further includes second longitudinal portions 144 and 146, which extend from the transverse portions 150 along the insulating barriers 148a and 148b of the first insulating element 120 to the first insulating capping layers 112a and 112b, respectively. The second longitudinal portions 144 and 146 are covered by the first insulating capping layers 112a and 112b, respectively, and the first insulating capping layers 112a and 112b also at least partially cover the first doped region 102. The second longitudinal portions 144 and 146 abut against the insulating barriers 148a and 148b in the longitudinal direction, thereby physically isolating the emitter region 105 from the insulating barriers 148a and 148b. Therefore, the emitter region 105 is physically divided into at least two sub-emitter regions by the first longitudinal portion 142 and the second longitudinal portions 144 and 146 of the base region 106: a first sub-emitter region 105a composed of a first doped region 102a and a second doped region 104a, and a first sub-emitter region 105b composed of a first doped region 102b and a second doped region 104b. Each sub-emitter region 105a and 105b is surrounded by the first and second longitudinal portions 142, 144, and 146 of the base region 106, with only a portion of the first doped regions 102a and 102b of the sub-emitter regions 105a and 105b exposed to the microfluidic channel 122. As described below, the number and structure of the sub-emitter regions can vary and depend at least in part on the number and arrangement of the first and second longitudinal portions of the base region.

[0046] The first longitudinal portion 142 has a first width W1, the second longitudinal direction 144 has a second width W2, and the second longitudinal direction 146 has a third width W3. The first width W1, the second width W2, and the third width W3 may have the same or different values. In this embodiment, the second width W2 and the third width W3 may be substantially equal. For example, the ratio of the second width W2 to the third width W3 may be approximately 1:10 to approximately 10:1, or approximately 1:5 to approximately 5:1, or approximately 1:3 to 3:1, or approximately 1:1.5 to 1.5:1, or approximately 1:1.2 to approximately 1.2:1, or approximately 1:1. The first width W1 may be less than or equal to the second width W2 or the third width W3. For example, the ratio of the first width W1 to the second or third width W2 or W3 is about 1:1 to about 1:10, or about 1:1 to about 1:8, or about 1:1 to about 1:6, or about 1:1 to about 1:4, or about 1:1 to about 1:3, or about 1:1.

[0047] For example, the first width W1, the second width W2, and the third width W3 are independently about 100 nm to about 1,000 nm, for example, about 100 nm to about 800 nm, or about 100 nm to about 600 nm, or about 100 nm to about 400 nm, or about 100 nm to about 200 nm, or about 200 nm to about 1,000 nm, or about 200 nm to about 800 nm, or about 200 nm to about 600 nm, or about 200 nm to about 400 nm, or about 400 nm to about 1,000 nm, or about 400 nm to about 800 nm, or about 400 nm to about 600 nm, or about 600 nm to about 1,000 nm, or about 600 nm to about 800 nm, or about 800 nm to about 1,000 nm.

[0048] refer to Figure 1B It shows Figure 1A A partial top view of the optical tweezers device is shown (the first electrode 124 is omitted for clarity). Dashed lines indicate the base region 106 covered by the first insulating capping layer 112 and the second insulating element 140; for simplicity, only the base regions of two transistors are shown. As shown, the base region 106 includes two first longitudinal portions 142a and 142b that are perpendicular and intersecting each other in the lateral and vertical directions, and second longitudinal portions 144 and 146. The first and second longitudinal portions together physically divide the emitter region into four sub-emitter regions, shown as first doped regions 102a, 102b, 120c, and 102d. In this embodiment, the first longitudinal portions 142a and 142b have equal widths W1. In other embodiments, the first longitudinal portions 142a and 142b may have unequal widths.

[0049] Figure 1C Showing Figure 1A A partial cross-sectional view of an array of phototransistors 126 as shown. Figure 1D Displayed contains Figure 1A This is a schematic diagram of a portion of a microfluidic device 136 comprising an optical tweezers device with a structure shown in the diagram. The microfluidic device 136 includes an optical tweezers device and a control system 138. The control system 138 typically includes a computer system 134 and an image acquisition device 132 and a light pattern generation device 130 communicatively connected to the computer system 134. The image acquisition device 132 is used to acquire images of the microfluidic channel and / or micropores, such as a camera with a CCD chip. The light pattern generation device 130 is used to generate a patterned light beam to excite the transistor. The intensity of the light beam can be approximately 0.1 W / cm². 2 Up to approximately 1000 W / cm 2 The computer system 134 is communicatively connected to the optical tweezers device and controls the interaction between the image acquisition device 132, the optical pattern generation device 130, and the optical tweezers device according to preset instructions to complete microfluidic operations.

[0050] In this embodiment, one or more longitudinal portions 142, 144, and 146 extend from the lateral portion 150 of the base region 106, physically isolating the emitting region 105 into multiple sub-emitting regions 105a and 105b. These sub-emitting regions share the base region 106 and the collector region 108. On one hand, the longitudinal portions 142, 144, and 146 extend from the lateral portion 150 to the insulating capping layers 112 and 140, thus being closer to the light beam and receiving greater light intensity. Under the same illumination intensity, the base region 106 in this embodiment can receive more photons compared to a base region without longitudinal portions. On the other hand, the transmittance of the material constituting the insulating capping layers 112 and 140 (e.g., SiO2) is better than the transmittance of the material of the emitting region 105 covering the base region 106 (e.g., crystalline silicon). Therefore, the longitudinal portions 142, 144, and 146 of the base region 106 can also receive more photons. Therefore, this transistor structure achieves a larger photocurrent without changing the intensity of the irradiated beam or the window size of the transistor, thereby generating a larger DEP force, which facilitates the manipulation of micro-objects in microfluidic channels. Furthermore, compared to an undivided emitter region, the presence of multiple sub-emitter regions results in a denser and more uniform distribution of the non-uniform electric field generated by illumination, further enhancing the manipulation of micro-objects.

[0051] Figure 2A A partial cross-sectional view of a transistor array in an optical tweezers device according to another embodiment of the present invention is shown. Figure 2BA partial top view of the transistor array is shown. For simplicity, only one window of the base region 206 is shown as a dashed line. The illustrated transistor array is similar to the embodiment shown in Figure 1, except that the number of first vertical portions of the base region 206 is greater. In the illustrated embodiment, there are four first vertical portions, namely first vertical portions 242a, 242b, 242c, and 242d, wherein first vertical portions 242a and 242b are parallel in the same direction and intersect perpendicularly with the parallel first vertical portions 242c and 242d. The first vertical portions 242a, 242b, 242c, and 242d, together with the second vertical portions 248a, 248b, 248c, and 248d, physically divide the emitter region 205 into nine sub-emitter regions, shown as first doped regions 102a to 102h. The widths of the four first vertical portions are W1a, W1b, W1c, and W1d, which may be equal or unequal. Widths W1a, W1b, W1c, and W1d are each independently approximately 100 nm to approximately 1,000 nm. Widths W2, W3, W4, and W5 of the second longitudinal portion are each independently approximately 100 nm to approximately 1,000 nm, and their ratios are as described above regarding the relationship between W2 and W3. The ratios of W1a to W1d to W2, W3, W4, or W5 are as described above regarding the relationship between W1 and W2 or W3.

[0052] It is foreseeable that the number and orientation of the first longitudinal sections can vary. For example, there can be two, three, four, or more first longitudinal sections, which can be in the same or opposite direction, and can be angular, parallel, or perpendicular. For example, the first longitudinal sections can be two parallel longitudinal sections in the same direction, thus dividing the emission area into three sub-emission areas together with the second longitudinal section. These three sub-emission areas can be of equal volume. Furthermore, these three sub-emission areas can be cuboids. As another example, the number of first longitudinal sections is three, with two parallel in the same direction and the third intersecting them perpendicularly, thus dividing the emission area into six sub-emission areas together with the second longitudinal section. These six sub-emission areas can be of equal volume. Furthermore, these six sub-emission areas can be cubes. Those skilled in the art will also anticipate that multiple first longitudinal sections can be arranged at angles to obtain an emission area with a non-rectangular cross-section. Those skilled in the art will also anticipate that the number of sub-emission areas can be odd.

[0053] Figure 3A partial cross-sectional view of a transistor array in an optical tweezers device according to another embodiment of the present invention is shown. The illustrated transistor array is similar to that shown in FIG1, except that the base region 306 includes a lateral portion 350 and a first longitudinal portion 342, but does not include at least one second longitudinal portion extending along the insulating barrier 348 to the insulating capping layer 312. In this embodiment, the lateral portion 350 of the base region 306 extends laterally and abuts against the insulating barriers 348a, 348b. One end of at least one sub-emitter region abuts against the insulating barrier 348. Thus, the first longitudinal portion 342 of the base region 306, together with the first insulating element 320, physically isolates the emitter region 305 into at least two sub-emitter regions 305a and 305b. As previously mentioned, each sub-emitter region may be composed of a first doped region 302a or 302b and a second doped region 304a or 304b. Therefore, at least one sub-emitting region is physically isolated by the lateral portion 350 of the base region 306, the first longitudinal portion 342, and the insulating barrier 348 of the first insulating element 320, with only a portion of the first emitting regions 302a and 302b exposed to the microfluidic channel.

[0054] It is foreseeable that the base region 306 may not include any second longitudinal portion, i.e., it may not include a longitudinal portion extending along the insulating barrier 348 to the insulating cover layer 312 in any direction. Alternatively, the base region 306 may include a second longitudinal portion in one or more directions, such that at least one sub-emitting region is physically isolated by the lateral portion 350 of the base region 306, the first longitudinal portion 342, and the insulating barrier 348 of the first insulating element 320, and at least one sub-emitting region is physically isolated by the lateral portion 350, the first longitudinal portion 342, and the second longitudinal portion of the base region 306. It is also foreseeable that the number, orientation, and arrangement of the first longitudinal portions 342 may be varied as described above, thereby changing the number, volume, and arrangement of the sub-emitting regions.

[0055] Figure 4 A partial cross-sectional view of a transistor array in an optical tweezers device according to another embodiment of the present invention is shown. The illustrated transistor array is... Figure 3The illustrated embodiment is similar, except that the number of first longitudinal portions of the base region 406 is greater. In the illustrated embodiment, there are two first longitudinal portions, 442a and 442b. The first longitudinal portions 442a and 442b are parallel to each other and extend vertically to the insulating barrier 448. The first longitudinal portions 442a and 442b, together with the first insulating elements 420a and 420b and the transverse portion 350 of the base region 406, physically divide the emission region 405 into three sub-emission regions 405a, 405b, and 405c. In this embodiment, at least one sub-emission region 405b is physically isolated by the transverse portion 450 of the base region 406 and the first longitudinal portions 442a and 442b, and at least two sub-emission regions 405a and 405c are physically isolated by the transverse portion 450 of the base region 406, the first longitudinal portion 442a or 442b, and the first insulating element 420a or 420b. It is foreseeable that the number, orientation and arrangement of the first longitudinal portion 442 can be changed as described above, thereby altering the number, volume and arrangement of the sub-emission regions.

[0056] The transistor, optical tweezers device, and microfluidic device provided by this invention can be fabricated using conventional techniques in the art. Those skilled in the art, based on the current level of semiconductor manufacturing processes and in conjunction with the illustrations and descriptions in this specification, can fabricate the transistor of this invention without further explanation. This is merely an example. Figure 5 The schematic illustration shows a method 500 for manufacturing the phototransistor of the present invention.

[0057] Method 500 includes step 502, which provides a semiconductor substrate (e.g., silicon) comprising a doped substrate layer and an undoped layer thereon, the doped substrate layer being used to form the substrate layer in the embodiments of the present invention, and the undoped layer being used to form the collector region, base region, and emitter region in the embodiments of the present invention.

[0058] In step 504, a collector doped layer is formed immediately adjacent to the doped substrate layer on the undoped layer. The collector doped layer forms the collector region in this embodiment of the invention. The collector doped layer and the doped substrate layer may have the same doping type (e.g., both are N-type doped), but may have different doping concentrations. For example, the collector doped layer may be a lightly doped layer, and the doped substrate layer may be a heavily doped layer. The semiconductor material obtained after step 504 includes the doped substrate layer and the collector doped layer.

[0059] Step 506 involves forming trenches in the obtained semiconductor material and filling the trenches with an electrically insulating material (e.g., SiO2). The trenches penetrate the collector-doped layer and extend into the doped substrate layer, thereby forming the insulating barrier in the embodiments of the present invention.

[0060] Furthermore, in step 508, a base doped layer is formed in the collector doped layer by ion implantation. The base doped layer has a different doping type (e.g., P-type doping) than the collector doped layer and the doped substrate layer. By controlling parameters such as the ion implantation time, speed, and implantation amount, the thickness of the formed base doped layer and collector doped layer can be controlled to meet the thickness requirements of the present invention.

[0061] In step 510, multiple sub-emitter doped layers are formed in the base doped layer by ion implantation. The emitter doped layers have a different doping type (e.g., N-type doping) than the base doped layer. The emitter doped layers can be formed through independent ion implantation steps to create first and second doped layers with different doping concentrations. For example, the doping concentration of the first doped layer is higher than that of the second doped layer, thus forming the first and second doped regions of the emitter region in this embodiment of the invention. Similarly, by controlling parameters such as the ion implantation time, speed, and implantation amount, the thicknesses of the formed first, second, and base doped layers can be controlled to meet the requirements of this invention regarding the thickness of each layer.

[0062] It is worth noting that although the doping type and doping level are shown in the figure, those skilled in the art will know that the NPN transistor shown can be replaced by a PNP transistor structure without affecting the achievement of the objectives of the various embodiments of the present invention.

[0063] The above descriptions are representative examples of embodiments of the present invention and are provided for illustrative purposes only. The present invention contemplates that one or more technical features used in one embodiment can be added to another embodiment to form improved or alternative embodiments without departing from the purpose of the embodiment. Similarly, one or more technical features used in one embodiment can be omitted or replaced without departing from the purpose of the embodiment to form alternative or simplified embodiments. Furthermore, one or more technical features used in one embodiment can be combined with one or more technical features in another embodiment without departing from the purpose of the embodiment to form improved or alternative embodiments. The present invention is intended to include all of the above-mentioned improved, alternative, and simplified technical solutions.

Claims

1. A transistor optical tweezers, comprising: First electrode; The second electrode is electrically connected to the first electrode; An array of phototransistors is disposed between the first electrode and the second electrode. The array of phototransistors is composed of phototransistors arranged in an array. Each phototransistor is physically isolated from each other by a first insulating element. Each phototransistor includes a collector region, a base region, and an emitter region supported by a substrate. The microfluidic channel disposed between the first electrode and the phototransistor array is characterized in that, For each phototransistor, its emitter region includes at least two sub-emitter regions, and the at least two sub-emitter regions share a common base region and collector region. Each sub-emitter region includes a first doped region and a second doped region, wherein the second doped region is adjacent to the base region, and the first doped region is disposed above the second doped region. The base region includes a lateral portion and a longitudinal portion extending from the lateral portion to a first insulating element. The longitudinal portion includes a first longitudinal portion extending from the lateral portion of the base region to a second insulating element and at least partially physically isolating the sub-emitting region. The second insulating element completely covers the first longitudinal portion and at least partially covers the first doped region.

2. The transistor optical tweezers according to claim 1, characterized in that, At least one sub-emitting region is physically isolated by a lateral portion of the base region, a first longitudinal portion of the base region, and the first insulating element.

3. The transistor optical tweezers according to claim 1, characterized in that, The longitudinal portion includes a second longitudinal portion that abuts against and extends along at least one of the first insulating elements, the second longitudinal portion being spaced apart from the first longitudinal portion.

4. The transistor optical tweezers according to claim 3, characterized in that, At least one sub-emission region is physically isolated by a lateral portion of the base region, a first longitudinal portion of the base region, and a second longitudinal portion of the base region.

5. The transistor optical tweezers according to claim 1, characterized in that, The first longitudinal portion includes a plurality of first longitudinal portions that are parallel and / or perpendicular to each other.

6. The transistor optical tweezers according to claim 5, characterized in that, At least one sub-emission region is physically isolated only by the lateral portion of the base region and the first longitudinal portion of the base region.

7. The transistor optical tweezers according to claim 1, characterized in that, Each sub-emission region is surrounded by a base region but is at least partially exposed to the microfluidic channel.

8. The transistor optical tweezers according to claim 3, characterized in that, The first vertical portion has a first width, and the second vertical portion has a second width, wherein the first width and the second width are independently between 100 nm and 1000 nm.

9. The transistor optical tweezers according to claim 5, characterized in that, The width of each of the first longitudinal portions is independently between 100 nm and 1000 nm.

10. The transistor optical tweezers according to any one of claims 1 to 9, characterized in that, The doping concentration of the first doped region is higher than that of the second doped region.

11. The transistor optical tweezers according to claim 10, characterized in that, The doping concentration of the first doped region is 10. 18 cm -3 Up to 10 21 cm -3 The doping concentration of the second doped region is 10. 15 cm -3 Up to 10 18 cm -3 .

12. The transistor optical tweezers according to any one of claims 1 to 9, characterized in that, Each phototransistor's emitter region comprises three, four, six, eight, or nine sub-emitter regions.

13. The transistor optical tweezers according to any one of claims 1 to 9, characterized in that, Each sub-emission region has an equal volume.

14. The transistor optical tweezers according to any one of claims 1 to 9, characterized in that, Each phototransistor's collector region extends laterally into the first insulating element and has no longitudinal extension.

15. The transistor optical tweezers according to claim 1, characterized in that, Each phototransistor is spaced apart at a distance of 5 to 20 micrometers.

16. The transistor optical tweezers according to claim 1, characterized in that, The microfluidic channel contains a conductive medium with cells.

17. A microfluidic device comprising the transistor optical tweezers according to any one of claims 1 to 16.

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