A method for fabricating a microfluidic photoconductive switch, the switch, and the switch mold.

Abstract

This invention provides a method for fabricating a microfluidic photoconductive switch, a switch, and a switch mold. The method includes: performing electro-jet printing on a polished silicon wafer to obtain a switch mold; pouring the prepared PDMS liquid into the switch mold to obtain an initial photoconductive switch, the initial photoconductive switch including a microchannel and a control channel; modifying the microchannels of the initial photoconductive switch to obtain a modified photoconductive switch; and injecting photoconductive liquid into the control channel and microchannels of the modified photoconductive switch to obtain a microfluidic photoconductive switch. This invention utilizes electro-jet printing technology to obtain a switch mold, and then obtains a microfluidic liquid photoconductive switch through pouring and channel modification. Compared with existing microfluidic photoconductive device fabrication methods, this invention has a simpler manufacturing process, is easier to operate, and has lower costs, and can be widely applied in the fabrication of various photoconductive devices.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication technology, and in particular to a method for fabricating a microfluidic photoconductive switch, the switch itself, and a switch mold. Background Technology

[0002] With the continuous development and improvement of microfluidics technology, it has begun to be effectively integrated with other technologies, providing new directions for traditional science. Microfluidic liquid photoconductors are a typical example, representing a new application direction formed by combining modern optics with microfluidics. By manipulating the fluid within the channel, microfluidic liquid photoconductor devices can change the optical properties of the device and achieve specific optical functions.

[0003] However, existing microfluidic photoconductive devices typically require traditional photolithography, plasma etching, and wet etching processes for fabrication, necessitating the use of optical masks. These processes are costly, lack flexibility, and are complex. Therefore, a method for fabricating microfluidic photoconductive switches, along with a switch and switch mold, is needed to achieve simple and rapid fabrication of microfluidic photoconductive switches. Summary of the Invention

[0004] In view of the above problems, embodiments of the present invention provide a method for fabricating a microfluidic photoconductive switch, a switch, and a switch mold, so as to overcome the above problems or at least partially solve the above problems.

[0005] A first aspect of this invention provides a method for fabricating a microfluidic photoconductive switch, the method comprising:

[0006] Electro-jet printing is performed on a polished silicon wafer to obtain a switch mold;

[0007] The prepared PDMS liquid was used to cast the switch mold to obtain an initial photoconductive switch, which includes a microchannel and a control channel.

[0008] The initial photoconductive switch was modified using microfluidics to obtain a modified photoconductive switch;

[0009] Photoconductive liquid is injected into the control channel and microchannel of the modified photoconductive switch to obtain a microfluidic photoconductive switch.

[0010] Optionally, an electro-jet printing process is performed on a polished silicon wafer to obtain a switch mold, comprising:

[0011] The polished silicon wafer is cleaned and then dried.

[0012] Using PEO material, an electro-jet printing process is performed on the polished silicon wafer to obtain a double-triangular cavity. The double-triangular cavity is composed of two right-angled triangles, the longest sides of which are spaced apart and parallel to each other, so that the top view of the two right-angled triangles forms a rectangular shape.

[0013] Using PVP material, an electro-jet printing process is performed on the polished silicon wafer to obtain an optical guide channel. The optical guide channel includes a control channel and two pairs of microchannels. The control channel is located in the middle of the longest side of the two right triangles. Each pair of microchannels consists of two short channels with the same direction, which can be connected to form a straight line that passes through the control channel.

[0014] The polished silicon wafer is placed on a hot press and hot-pressed to obtain the switch mold.

[0015] Optionally, the polished silicon wafer is placed on a hot press for hot pressing to obtain the switch mold, comprising:

[0016] Place another cleaned and dried silicon wafer on the polished silicon wafer;

[0017] The polished silicon wafer is placed on the hot press, and the hot pressing temperature of the hot press is controlled at 60°C and the hot pressing pressure is 5 kPa. The hot pressing is carried out for 5 minutes to obtain the switch mold.

[0018] Optionally, a photoconductive liquid is injected into the control channel and microchannel of the modified photoconductive switch to obtain a microfluidic photoconductive switch, comprising:

[0019] Inject photoconductive liquid into the control channel of the modified photoconductive switch, such that the photoconductive liquid occupies one-third of the volume of the control channel;

[0020] The control flow channel is connected using a control pump;

[0021] Inject photoconductive liquid into the microchannel of the modified photoconductive switch;

[0022] The microfluidic photoconductive switch is obtained by connecting the microchannel with an optical fiber.

[0023] Optionally, the switch mold is cast using the prepared PDMS liquid to obtain an initial photoconductive switch, comprising:

[0024] The PDMS liquid is poured onto the switch mold;

[0025] The switch mold is then subjected to vacuuming followed by heat curing.

[0026] Demolding is performed to obtain the cured PDMS switch;

[0027] The cured PDMS switch is then subjected to heat treatment;

[0028] The cured PDMS switch is placed on a glass slide and subjected to oxygen plasma treatment to obtain the initial photoconductive switch.

[0029] Optionally, the initial photoconductive switch is modified using microfluidics to obtain a modified photoconductive switch, comprising:

[0030] Silver nitrate solid powder was added to deionized water at a mass ratio of 25:4 to obtain the first solution;

[0031] Ammonia was added to the first solution at a volume ratio of 4000:65 to obtain the second solution;

[0032] According to the mass ratio of glucose powder to silver nitrate powder of 80:25, glucose powder is added to the second solution to obtain a silver plating solution;

[0033] The silver plating solution is poured into the microchannels and control channels of the initial photoconductive switch;

[0034] The initial photoconductive switch was placed in an oven for heating to obtain the modified photoconductive switch.

[0035] Optionally, the initial switch is modified with microchannels to obtain a modified photoconductive switch, comprising:

[0036] A third solution was prepared and mixed with fluorosilane, ethanol and water in a mass ratio of 1:40:9.

[0037] Add acetic acid dropwise to the third solution until the pH value is adjusted to 4 to obtain the fourth solution;

[0038] The fourth solution was stirred with a magnetic stirrer for 10-15 minutes to obtain a fluorine-containing mixture.

[0039] The fluorine-containing mixture is poured into the microchannel and control channel of the initial photoconductive switch, and after standing for 5 minutes, the fluorine-containing mixture is extracted.

[0040] The modified photoconductive switch was obtained by rinsing with ethanol and deionized water and then drying.

[0041] Optionally, the PDMS liquid is prepared by the following steps:

[0042] Pour the PDMS prepolymer and curing agent into a petri dish at a volume ratio of 10:1 and mix thoroughly.

[0043] The culture dish was placed in a vacuum oven and vacuum-treated to obtain the PDMS liquid;

[0044] Optionally, electro-jet printing is performed on the polished silicon wafer to obtain a double triangular cavity, comprising:

[0045] The electro-jet printing voltage is controlled within the range of 1500-3000 volts, the printhead height is within the range of 0.5-1 cm, and the PEO ink flow rate is 2-5 ml / min. Electro-jet printing is performed on the polished silicon wafer to obtain the double triangular cavity. The line diameter of the double triangular cavity is within the range of 50-60 micrometers, and the distance between the longest sides of the two right triangles is within the range of 100-120 micrometers.

[0046] Electro-jet printing is performed on the polished silicon wafer to obtain an optical guide channel, including:

[0047] The electro-jet printing voltage is controlled within the range of 2000-3000 volts, the printhead height is within the range of 0.5-1 cm, and the PVP ink flow rate is 1-3 ml / min. Electro-jet printing is performed on the polished silicon wafer to obtain the light guide channel, the diameter of which is within the range of 10-30 micrometers.

[0048] A second aspect of the present invention also provides a microfluidic photoconductive switch, which is prepared by the microfluidic photoconductive switch preparation method described in the first aspect of the present invention.

[0049] A third aspect of the present invention also provides a switch mold for fabricating a microfluidic photoconductive switch, the switch mold being obtained by electro-jet printing on a polished silicon wafer.

[0050] This invention provides a method for fabricating a microfluidic photoconductive switch, a switch, and a switch mold. The method includes: performing electro-jet printing on a polished silicon wafer to obtain a switch mold; pouring the prepared PDMS liquid into the switch mold to obtain an initial photoconductive switch, the initial photoconductive switch including a microchannel and a control channel; modifying the microchannels of the initial photoconductive switch to obtain a modified photoconductive switch; and injecting photoconductive liquid into the control channel and microchannel of the modified photoconductive switch to obtain a microfluidic photoconductive switch. This invention utilizes electro-jet printing technology to obtain a switch mold, and then obtains a microfluidic liquid photoconductive switch through pouring and channel modification. Compared with existing microfluidic photoconductive device fabrication methods, this invention has a simpler manufacturing process, is easier to operate, and has lower costs, and can be widely applied in the fabrication of various photoconductive devices. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a flowchart illustrating the steps of a microfluidic photoconductive switch fabrication method provided in an embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram of a double-triangular cavity structure provided in an embodiment of the present invention;

[0054] Figure 3 This is a schematic diagram of the structure of a switch mold provided in an embodiment of the present invention;

[0055] Figure 4 This is a schematic diagram of the structure of a message transmission device provided in an embodiment of the present invention;

[0056] Figure descriptions: 1-Fiber optic input port of the microchannel; 2-Fiber optic output port of the microchannel; 3-Control port; 4-Control channel; 5-Microchannel at the fiber optic input end; 6-Microchannel at the fiber optic output end. Detailed Implementation

[0057] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0058] First, a brief explanation of the relevant technical terms involved in the embodiments of the present invention will be given.

[0059] Electrohydrodynamic jet printing is based on electrohydrodynamic theory. It utilizes the combined effects of an electric field and other forces to form a stable, fine jet at the nozzle exit, much smaller than the nozzle's inner diameter. This jet is then used to directly pattern functional materials onto a substrate at room temperature and pressure. Electrohydrodynamic printing offers advantages such as high printing precision, wide ink adaptability, strong controllability of printing droplets, and low substrate requirements.

[0060] PDMS, also known as polydimethylsiloxane, is a polymer commonly used in the manufacture of microfluidic chips. PDMS is frequently used in microfluidic chip fabrication because it is transparent at optical frequencies (240nm-1100nm), facilitating observation of the contents of the microchannels. It also exhibits low fluorescence properties, some biocompatibility, and a degree of deformability, allowing for the integration of microchannel valves through the deformation of PDMS microchannels. Furthermore, it is inexpensive and easy to mold.

[0061] The following are the specific contents of the embodiments of the present invention.

[0062] This invention provides a method for fabricating a microfluidic photoconductive switch, referring to... Figure 1 , Figure 1 A flowchart illustrating the steps of a microfluidic photoconductive switch fabrication method is shown, as follows: Figure 1 As shown, the method includes:

[0063] Step S101: Electro-jet printing is performed on a polished silicon wafer to obtain a switch mold;

[0064] Existing methods for fabricating microfluidic liquid photoconductor devices require specialized optical masks and traditional processes such as photolithography, plasma etching, and wet etching. These methods are costly, inflexible, and complex. Furthermore, fabricating microfluidic liquid photoconductor devices with different heights and widths necessitates the creation of new optical masks and repeated spin coating to form photoresist substrates of varying thicknesses. Especially during the design and dimensional optimization of microfluidic liquid photoconductor devices, the fabrication of numerous sample devices is required, resulting in long development cycles and high costs. This embodiment utilizes electrojet technology to directly fabricate the required switch mold. The manufacturing process is simple, requires no optical mask, is convenient, and lower in cost. In this embodiment, the switch mold is a microfluidic liquid photoconductor switch mold, which includes the control channels and microchannels required for the liquid photoconductor switch, as well as the corresponding switch cavity. The specific size and model of the switch mold can be set according to actual application needs.

[0065] In one embodiment, an electro-jet printing process is performed on a polished silicon wafer to obtain a switch mold, comprising:

[0066] Step S1011: Clean and dry the polished silicon wafer;

[0067] Specifically, the polished silicon wafer can be a single-sided polished silicon wafer. During cleaning, it can be cleaned using a certain amount of sulfuric acid, hydrofluoric acid, and deionized water to remove dust, impurities, and oxide layers from the surface of the silicon wafer. The cleaned silicon wafer is then placed in an oven for drying, with the oven temperature set at 220°C and the baking time at 30 minutes.

[0068] Step S1012: Using PEO material, electro-jet printing is performed on the polished silicon wafer to obtain a double-triangular cavity. The double-triangular cavity is composed of two right-angled triangles. The longest sides of the two right-angled triangles are spaced a certain distance apart and are parallel to each other, so that the top view of the two right-angled triangles forms a rectangular shape.

[0069] Specifically, the PEO material is polyethylene oxide, which is printed on the polished silicon wafer using electro-jet printing technology to obtain a double-triangular cavity. This double-triangular cavity serves as the cavity structure for the switching device, providing protection and support for the microchannels and control channels within it. (Refer to...) Figure 2 , Figure 2 A schematic diagram of a double-triangular cavity structure is shown, as follows: Figure 2 As shown, the cavity is composed of two right triangles. The longest sides of the two right triangles are spaced a certain distance apart and are parallel to each other, so that the top view of the two right triangles forms a rectangular shape. The middle gap between the two right triangles is a reserved position for the control channel. Multiple parallel lines are distributed at a certain interval inside the right triangles.

[0070] In one embodiment, electro-jet printing is performed on the polished silicon wafer to obtain a double-triangular cavity, comprising:

[0071] The electro-jet printing voltage is controlled within the range of 1500-3000 volts, the printhead height is within the range of 0.5-1 cm, and the PEO ink flow rate is 2-5 ml / min. Electro-jet printing is performed on the polished silicon wafer to obtain the double triangular cavity. The line diameter of the double triangular cavity is within the range of 50-60 micrometers, and the distance between the longest sides of the two right triangles is within the range of 100-120 micrometers.

[0072] Step S1013: Using PVP material, electro-jet printing is performed on the polished silicon wafer to obtain a light guide channel; the light guide channel includes one control channel and two pairs of micro channels. The control channel is located in the middle of the longest side of the two right triangles. Each pair of micro channels consists of two short channels. The two short channels are in the same direction and can be connected into a straight line, which passes through the control channel.

[0073] Specifically, the PVP material is polyvinylpyrrolidone, a non-ionic polymer compound. In this embodiment, based on the double-triangular cavity of the polished silicon wafer, the photoconductive channel of the photoconductive switch is further printed using electro-jet printing technology. This photoconductive channel is divided into a microchannel and a control channel. (Refer to...) Figure 3 , Figure 3 A schematic diagram of a switch mold structure is shown, such as... Figure 3As shown, the black lines represent the microchannels generated by electro-jet printing using PVP material. 4 indicates the control channel, 5 indicates the microchannel at the fiber optic input, and 6 indicates the microchannel at the fiber optic output. Figure 3 As shown, the prepared optical guiding channel includes a control channel (4), which controls the opening and closing of the switch by adjusting the position of the optical guiding liquid in the channel. The optical guiding channel also includes two pairs of microchannels. Each pair of microchannels consists of a microchannel (5) at the optical fiber input end and a microchannel (6) at the optical fiber output end. These two short channels are connected to the optical fiber respectively, with one end being the input end and the other end being the output end. Therefore, the two short channels are in the same direction and can be connected into a straight line, which passes through the control channel.

[0074] In one embodiment, an electro-jet printing process is performed on the polished silicon wafer to obtain an optical guide channel, including:

[0075] The electro-jet printing voltage is controlled within the range of 2000-3000 volts, the printhead height is within the range of 0.5-1 cm, and the PVP ink flow rate is 1-3 ml / min. Electro-jet printing is performed on the polished silicon wafer to obtain the light guide channel, the diameter of which is within the range of 10-30 micrometers.

[0076] Step S1014: The polished silicon wafer is placed on a hot press for hot pressing to obtain the switch mold.

[0077] Specifically, the mold obtained after electro-jet printing is placed in a hot press and solidified by hot pressing to obtain a stable switch mold. Compared to traditional manufacturing techniques such as photolithography, which can only produce microfluidic channels with rectangular cross-sections, electro-jet printing can directly produce channels with circular cross-sections due to its technical characteristics. It's important to know that optical fibers used in communication have circular cross-sections because circular structures can better and more uniformly reflect incident light and are not limited by the angle of the incident light. Therefore, this embodiment utilizes electro-jet technology to directly generate optical guide channels with circular cross-sections. The method is simple, not limited by specialized equipment, and can be widely applied in the fabrication and production of optical guide devices.

[0078] In one embodiment, the polished silicon wafer is placed on a hot press for hot pressing to obtain the switch mold, comprising:

[0079] Place another cleaned and dried silicon wafer on the polished silicon wafer;

[0080] The polished silicon wafer is placed on the hot press, and the hot pressing temperature of the hot press is controlled at 60°C and the hot pressing pressure is 5 kPa. The hot pressing is carried out for 5 minutes to obtain the switch mold.

[0081] In this embodiment, the hot pressing effect is controlled by adjusting the parameters of the hot press. Specifically, since the melting point of PVP material is 130℃ and the melting point of PEO material is 65℃, only the double triangular cavity of PEO material is flattened by the silicon wafer during the hot pressing process, while the PVP lines still maintain a circular cross-section.

[0082] Step S102: The prepared PDMS liquid is used to pour the switch mold to obtain an initial photoconductive switch, which includes a microchannel and a control channel.

[0083] PDMS, also known as polydimethylsiloxane, is a polymer commonly used in the manufacture of microfluidic chips. By mixing it with a suitable crosslinking agent and pouring the mixture into a prepared switch mold, followed by heating and curing, a replica of the switch mold can be obtained, which can then be used as an initial photoconductive switch. Therefore, the structure of the switch mold determines the structure of the initial photoconductive switch; the switch mold includes microchannels and control channels, and the initial photoconductive switch also includes microchannels and control channels.

[0084] In one embodiment, the PDMS liquid is prepared by the following steps:

[0085] Pour the PDMS prepolymer and curing agent into a petri dish at a volume ratio of 10:1 and mix thoroughly.

[0086] The culture dish was placed in a vacuum oven and vacuum-treated to obtain the PDMS liquid.

[0087] In this embodiment, PDMS liquid is prepared using PDMS prepolymer and curing agent. Specifically, the PDMS prepolymer and curing agent are thoroughly mixed in a certain proportion. The curing agent can be a commonly used crosslinking agent, which is not limited in this embodiment. The mixed liquid is then evacuated in a vacuum oven at a vacuum degree of 100-150 Pa for 20-25 minutes to obtain PDMS liquid.

[0088] In one embodiment, the switch mold is cast using the prepared PDMS liquid to obtain an initial photoconductive switch, comprising:

[0089] Step S1021: Pour the PDMS liquid onto the switch mold;

[0090] Step S1022: After vacuuming the switch mold, heat curing treatment is performed.

[0091] Step S1023: Demolding is performed to obtain the cured PDMS switch;

[0092] Step S1024: Heat treatment is applied to the cured PDMS switch;

[0093] Step S1025: Place the cured PDMS switch on a glass slide and perform oxygen plasma treatment to obtain the initial photoconductive switch.

[0094] In this embodiment, the prepared PDMS liquid is poured onto the obtained switch mold, and a vacuum is applied to reduce porosity. Specific vacuuming parameters are: vacuum level 100-150 Pa, vacuuming time 10-15 minutes. After vacuuming, it undergoes heat curing, with the heating temperature controlled within the range of 65-70°C and the heating time 1-1.5 hours. After the PDMS liquid is completely cured, it is demolded to obtain the cured PDMS switch. Since a small amount of PVP and PEO remain in the cured PDMS switch, it is placed in a vacuum oven for heat treatment to remove the residual PEO and PVP. The pyrolysis process parameters are: vacuum level 200-300 Pa, heating temperature 300°C, heating time 20-30 minutes. Under this high-temperature environment, the residual PEO and PVP in the cured PDMS switch undergo a pyrolysis reaction, forming carbon dioxide gas, which is discharged through the microchannels. Finally, the cured PDMS switch was placed on a cleaned glass slide and subjected to oxygen plasma treatment. The oxygen plasma treatment power was 25-35 watts, the vacuum degree was 70-90 Pa, and the treatment time was 30-60 seconds. The oxygen plasma treatment enabled the glass slide and the PDMS substrate to fully adhere, achieving device bonding and obtaining the initial photoconductive switch. Thus, the structure of the initial photoconductive switch obtained by casting, demolding, and curing PDMS liquid in this embodiment is consistent with the switch model structure, which includes control channels and microchannels.

[0095] Step S103: Modify the initial photoconductive switch using microchannels to obtain the modified photoconductive switch;

[0096] In this embodiment, the initial photoconductive switch already has the structure of a complete switching device. Based on this structure, chemical reagents can be used to modify the initial photoconductive switch, thereby endowing the switching device with some required chemical properties and improving its performance.

[0097] In one embodiment, the initial photoconductive switch is modified with a microfluidic channel to obtain a modified photoconductive switch, comprising:

[0098] Step S1031: Add silver nitrate solid powder to deionized water at a mass ratio of 25:4 to obtain the first solution;

[0099] Step S1032: Add ammonia water to the first solution at a volume ratio of 4000:65 to obtain the second solution;

[0100] Step S1033: Add glucose powder to the second solution according to the mass ratio of glucose powder to silver nitrate powder of 80:25 to obtain silver plating solution;

[0101] Step S1034: Pour the silver plating solution into the microchannel and control channel of the initial photoconductive switch;

[0102] Step S1035: The initial photoconductive switch is placed in an oven for heating to obtain the modified photoconductive switch.

[0103] In this embodiment, firstly, silver nitrate solid powder is added to deionized water at a mass ratio of 25:4, that is, 250 mg of silver nitrate solid powder is added to every 40 ml of deionized water. Then, ammonia water is added at a volume ratio of 4000:65, that is, 650 μL of ammonia water is added to every 40 ml of the first solution. Then, glucose powder is added at a mass ratio of glucose powder to silver nitrate powder of 80:25, thereby obtaining a silver plating solution. This silver plating solution is poured into the microchannels and control channels of the initial photoconductive switch, ensuring full contact with the surfaces of the microchannels and control channels, and then placed in an oven for heating. Specifically, during the heating process, the heating temperature is controlled within the range of 40-50°C, and the heating time is 3-5 minutes, thereby allowing the silver plating solution to react fully and depositing a silver film with a thickness of approximately 200-300 nanometers in the microchannels and control channels of the initial photoconductive switch. Therefore, in this embodiment, the prepared silver plating solution is used to modify the initial photoconductive switch, coating the microchannel with a silver film. The silver film can improve the heat dissipation performance of the device, enabling it to operate normally at higher temperatures, thereby increasing the service life of the switching device.

[0104] In one embodiment, the initial switch is modified with microchannels to obtain a modified photoconductive switch, comprising:

[0105] Step S1031': Fluorosilane, ethanol and water are prepared and mixed in a mass ratio of 1:40:9 to obtain a third solution;

[0106] Step S1032': Add acetic acid dropwise to the third solution until the pH value is adjusted to 4 to obtain the fourth solution;

[0107] Step S1033': Stir the fourth solution with a magnetic stirrer for 10-15 minutes to obtain a fluorine-containing mixture;

[0108] Step S1034': The fluorine-containing mixture is poured into the microchannel and control channel of the initial photoconductive switch, and after standing for 5 minutes, the fluorine-containing mixture is extracted.

[0109] Step S1035': Rinse with ethanol and deionized water, then dry to obtain the modified photoconductive switch.

[0110] In this embodiment, fluorosilane, ethanol, and water are first prepared and mixed in a mass ratio of 1:40:9. Then, an acetic acid solution (acetic acid density 1.05 g / mL) is added, and the pH of the mixture is adjusted to 4. The mixture is stirred with a magnetic stirrer for 10-15 minutes to ensure thorough mixing, resulting in a fluorinated mixture. Next, the fluorinated mixture is poured into the microchannels and control channels of the initial photoconductive switch, ensuring full contact with the surfaces of the microchannels and control channels. After 5 minutes, the fluorinated mixture reacts fully, depositing a fluorinated thin film in the microchannels and control channels of the initial photoconductive switch. Finally, the liquid is extracted, rinsed with ethanol and deionized water, and then dried in an oven at 90-100°C for 20-30 minutes, yielding a modified photoconductive switch. The fluorinated material on the inner wall of the switch's channel helps improve the total optical reflection effect of the optical fiber and reduces propagation loss.

[0111] In this embodiment, different modifiers can be selected to modify the photoconductive switch according to the actual needs of the application. Specifically, the silver plating solution in the above embodiment can be selected to modify the photoconductive switch to obtain better heat dissipation performance. Alternatively, the fluorine-containing mixture in the above embodiment can be selected to modify the photoconductive switch to reduce the light propagation loss of the photoconductive switch. Or, the photoconductive switch can be modified with silver plating solution first, and then further improved with fluorine-containing mixture.

[0112] Step S104: Inject photoconductive liquid into the control channel and microchannel of the modified photoconductive switch to obtain a microfluidic photoconductive switch.

[0113] Therefore, this embodiment of the invention obtains a switch mold by electro-jet printing on a polished silicon wafer; the switch mold is then poured with the prepared PDMS liquid to obtain an initial photoconductive switch, which includes a microchannel and a control channel; the microchannel of the initial photoconductive switch is modified to obtain a modified photoconductive switch; and photoconductive liquid is injected into the control channel and microchannel of the modified photoconductive switch to obtain a microfluidic photoconductive switch. This embodiment of the invention utilizes electro-jet printing technology to obtain a switch mold, and then obtains a microfluidic liquid photoconductive switch through pouring and channel modification. Compared with existing microfluidic photoconductive device fabrication methods, the fabrication method proposed in this embodiment of the invention has a simpler manufacturing process, is easier to operate, and has lower costs. It can be widely applied in the fabrication of various photoconductive devices. Furthermore, the switch device fabricated according to this method has advantages such as miniaturization, high flexibility, high precision, simple structure, and ease of integration, and has broad application prospects.

[0114] In one embodiment, a photoconductive liquid is injected into the control channel and microchannel of the modified photoconductive switch to obtain a microfluidic photoconductive switch, comprising:

[0115] Inject photoconductive liquid into the control channel of the modified photoconductive switch, such that the photoconductive liquid occupies one-third of the volume of the control channel;

[0116] The control flow channel is connected using a control pump;

[0117] Inject photoconductive liquid into the microchannel of the modified photoconductive switch;

[0118] The microfluidic photoconductive switch is obtained by connecting the microchannel with an optical fiber.

[0119] In this embodiment, after completing a series of operations including casting, demolding, curing, and modification of the switch mold, photoconductive liquid can be injected into the control channel and microchannel of the photoconductive switch. Specifically, the photoconductive liquid fills the microchannel to ensure its light-guiding effect; only one-third of the photoconductive liquid is injected into the control channel, and a control pump is connected to one end of the control channel, allowing the position of the photoconductive liquid to be controlled. The microchannel is connected using optical fibers, specifically, as shown below. Figure 3 As shown, a pair of microchannels consists of a microchannel (5) at the fiber optic input end and a microchannel (6) at the fiber optic output end. These two short channels are connected to the fiber optic cable, with one end connected to the input end and the other end connected to the output end. Since the two short channels are aligned, they can be connected into a straight line. The control channel passes through the middle of these two short channels. The control pump moves the photoconductive liquid within the control channel to this straight line, allowing light emitted from the fiber optic input end to be transmitted to the fiber optic output end via the photoconductive liquid, thus achieving the connection of the switch. When the switch is closed, the control pump moves the position of the photoconductive liquid in the control channel again, preventing light emitted from the photoconductive input end from being transmitted to the photoconductive liquid and thus preventing it from being conducted to the fiber optic output end, thereby achieving the closure of the switch.

[0120] This embodiment also proposes a microfluidic photoconductive switch, which is prepared according to the microfluidic photoconductive switch preparation method described in any one of the above embodiments. (Refer to...) Figure 4 , Figure 4 A schematic diagram of the channel structure of a microfluidic photoconductive switch is shown. Figure 4In the diagram, 1 represents the fiber optic input port of the microfluidic channel, used to connect the input end of the optical fiber; 2 represents the fiber optic output port of the microfluidic channel, used to connect the output end of the optical fiber; 3 represents the control port, used to connect to the control pump to control the position of the photoconductive liquid in the control channel; 4 represents the control channel; 5 represents the microfluidic channel at the fiber optic input end; and 6 represents the microfluidic channel at the fiber optic output end. Therefore, the microfluidic photoconductive switch prepared in this embodiment has a simple structure, is easy to operate, and is low in cost, with broad application scenarios.

[0121] This embodiment also proposes a switch mold for fabricating a microfluidic photoconductive switch, which is obtained by electro-jet printing on a polished silicon wafer.

[0122] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0123] Embodiments of the present invention are described with reference to flowchart illustrations and / or block diagrams of methods, apparatuses, electronic devices, and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0124] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0125] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0126] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0127] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0128] The above provides a detailed description of the microfluidic photoconductive switch fabrication method, switch, and switch mold provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for fabricating a microfluidic photoconductive switch, characterized in that, The method includes: Electro-jet printing is performed on a polished silicon wafer to obtain a switch mold, specifically including: The polished silicon wafer is cleaned and then dried. Using PEO material, an electro-jet printing process is performed on the polished silicon wafer to obtain a double-triangular cavity. The double-triangular cavity is composed of two right-angled triangles, the longest sides of which are spaced apart and parallel to each other, so that the top view of the two right-angled triangles forms a rectangular shape. Using PVP material, an electro-jet printing process is performed on the polished silicon wafer to obtain an optical guide channel. The optical guide channel includes a control channel and two pairs of microchannels. The control channel is located in the middle of the longest side of the two right triangles. Each pair of microchannels consists of two short channels with the same direction, which can be connected to form a straight line that passes through the control channel. The polished silicon wafer is placed on a hot press and hot-pressed to obtain the switch mold; The prepared PDMS liquid was used to cast the switch mold to obtain an initial photoconductive switch, which includes a microchannel and a control channel. The initial photoconductive switch is modified using microchannels to obtain a modified photoconductive switch, wherein the modification includes: A silver film is formed on the inner wall of the flow channel by heating the pouring silver plating solution, or a fluorine-containing mixture is poured in and allowed to stand to deposit a fluorine-containing film. Photoconductive liquid is injected into the control channel and microchannel of the modified photoconductive switch to obtain a microfluidic photoconductive switch.

2. The method for fabricating a microfluidic photoconductive switch according to claim 1, characterized in that, The polished silicon wafer is placed on a hot press and hot-pressed to obtain the switch mold, comprising: Place another cleaned and dried silicon wafer on the polished silicon wafer; The polished silicon wafer is placed on the hot press, and the hot pressing temperature of the hot press is controlled at 60°C and the hot pressing pressure is 5 kPa. The hot pressing is carried out for 5 minutes to obtain the switch mold.

3. The method for fabricating a microfluidic photoconductive switch according to claim 1, characterized in that, Injecting photoconductive liquid into the control channel and microchannel of the modified photoconductive switch yields a microfluidic photoconductive switch, comprising: Inject photoconductive liquid into the control channel of the modified photoconductive switch, such that the photoconductive liquid occupies one-third of the volume of the control channel; The control flow channel is connected using a control pump; Inject photoconductive liquid into the microchannel of the modified photoconductive switch; The microfluidic photoconductive switch is obtained by connecting the microchannel with an optical fiber.

4. The method for fabricating a microfluidic photoconductive switch according to claim 1, characterized in that, The initial photoconductive switch is obtained by casting the prepared PDMS liquid into the switch mold, comprising: The PDMS liquid is poured onto the switch mold; The switch mold is then subjected to vacuuming followed by heat curing. Demolding is performed to obtain the cured PDMS switch; The cured PDMS switch is then subjected to heat treatment; The cured PDMS switch is placed on a glass slide and subjected to oxygen plasma treatment to obtain the initial photoconductive switch.

5. The method for fabricating a microfluidic photoconductive switch according to claim 1, characterized in that, The initial photoconductive switch is modified using microchannels to obtain a modified photoconductive switch, comprising: Silver nitrate solid powder was added to deionized water at a mass ratio of 25:4 to obtain the first solution; Ammonia was added to the first solution at a volume ratio of 4000:65 to obtain the second solution; According to the mass ratio of glucose powder to silver nitrate solid powder of 80:25, glucose powder is added to the second solution to obtain silver plating solution; The silver plating solution is poured into the microchannels and control channels of the initial photoconductive switch; The initial photoconductive switch was placed in an oven for heating to obtain the modified photoconductive switch.

6. The method for fabricating a microfluidic photoconductive switch according to claim 1, characterized in that, The initial photoconductive switch is modified using microchannels to obtain a modified photoconductive switch, comprising: A third solution was prepared and mixed with fluorosilane, ethanol and water in a mass ratio of 1:40:

9. Add acetic acid dropwise to the third solution until the pH value is adjusted to 4 to obtain the fourth solution; The fourth solution was stirred with a magnetic stirrer for 10-15 minutes to obtain a fluorine-containing mixture. The fluorine-containing mixture is poured into the microchannel and control channel of the initial photoconductive switch, and after standing for 5 minutes, the fluorine-containing mixture is extracted. The modified photoconductive switch was obtained by rinsing with ethanol and deionized water and then drying.

7. The method for fabricating a microfluidic photoconductive switch according to claim 1, characterized in that, The PDMS liquid was prepared through the following steps: Pour the PDMS prepolymer and curing agent into a petri dish at a volume ratio of 10:1 and mix thoroughly. The culture dish was placed in a vacuum oven and vacuum-treated to obtain the PDMS liquid.

8. The method for fabricating a microfluidic photoconductive switch according to claim 1, characterized in that, Electro-jet printing is performed on the polished silicon wafer to obtain a double-triangular cavity, comprising: The electro-jet printing voltage is controlled within the range of 1500-3000 volts, the printhead height is within the range of 0.5-1 cm, and the PEO ink flow rate is 2-5 ml / min. Electro-jet printing is performed on the polished silicon wafer to obtain the double triangular cavity. The line diameter of the double triangular cavity is within the range of 50-60 micrometers, and the distance between the longest sides of the two right triangles is within the range of 100-120 micrometers. Electro-jet printing is performed on the polished silicon wafer to obtain an optical guide channel, including: The electro-jet printing voltage is controlled within the range of 2000-3000 volts, the printhead height is within the range of 0.5-1 cm, and the PVP ink flow rate is 1-3 ml / min. Electro-jet printing is performed on the polished silicon wafer to obtain the light guide channel, the diameter of which is within the range of 10-30 micrometers.

9. A microfluidic photoconductive switch, characterized in that, The microfluidic photoconductive switch is prepared by the microfluidic photoconductive switch preparation method according to any one of claims 1-8.

10. A switching mold for fabricating microfluidic photoconductive switches, characterized in that, The switch mold is obtained by electro-jet printing on a polished silicon wafer, specifically including: The polished silicon wafer is cleaned and then dried. Using PEO material, an electro-jet printing process is performed on the polished silicon wafer to obtain a double-triangular cavity. The double-triangular cavity is composed of two right-angled triangles, the longest sides of which are spaced apart and parallel to each other, so that the top view of the two right-angled triangles forms a rectangular shape. Using PVP material, an electro-jet printing process is performed on the polished silicon wafer to obtain an optical guide channel. The optical guide channel includes a control channel and two pairs of microchannels. The control channel is located in the middle of the longest side of the two right triangles. Each pair of microchannels consists of two short channels with the same direction, which can be connected to form a straight line that passes through the control channel. The polished silicon wafer is placed on a hot press and hot-pressed to obtain the switch mold.

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