A structure variable signal detection sensor and a manufacturing method
By designing a signal detection sensor with a variable structure, and utilizing the stress-lifted whiskers to lift under force, the sensor structure can be switched, solving the problem that existing sensors cannot simultaneously detect multi-dimensional signals, and improving detection efficiency and flexibility.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNIV OF SCI & TECH OF CHINA
- Filing Date
- 2023-11-30
- Publication Date
- 2026-07-21
AI Technical Summary
Existing sensors cannot detect different signals simultaneously, resulting in low signal detection efficiency, necessitating the replacement of sensors for detection.
Design a signal detection sensor with variable structure. By stress-lifting whiskers that can bend under stress, the sensor structure can be switched from two-dimensional to three-dimensional, thus realizing multi-dimensional signal detection.
It improves the efficiency of signal detection, enabling the detection of corresponding signals in different dimensions, and enhances the flexibility and efficiency of signal detection.
Smart Images
Figure CN117664230B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of flexible sensor technology, and in particular to a signal detection sensor with a variable structure and its fabrication method. Background Technology
[0002] Flexible sensors can detect signals such as pressure, temperature, and humidity, and have broad application prospects in the field of flexible electronics. Currently, there are sensors that can detect pressure signals, and sensors that can detect temperature signals; however, because sensors that detect pressure signals cannot simultaneously detect temperature signals, it is necessary to switch to a different sensor when detecting different signals, resulting in low signal detection efficiency. Therefore, how to improve the efficiency of signal detection is a key issue of concern to those skilled in the art. Summary of the Invention
[0003] To address the aforementioned problems, this application provides a signal detection sensor with a variable structure and its fabrication method to improve the efficiency of signal detection. The embodiments of this application disclose the following technical solutions:
[0004] In a first aspect, this application discloses a signal detection sensor with a variable structure, the signal detection sensor comprising a flexible substrate, sensing whiskers and a composite conductive film, the sensing whiskers comprising stress-warped whiskers and stress-non-warped whiskers;
[0005] The stress-raised whiskers are connected to the stress-non-raised whiskers, the stress-non-raised whiskers are attached to the flexible substrate, and the composite conductive film is bonded to the stress-raised whiskers and the flexible substrate.
[0006] The stress-curved whiskers are used to curl up when subjected to bending or tensile stress, thereby converting the signal detection sensor from a two-dimensional structure to a three-dimensional structure.
[0007] Optionally, when the signal detection sensor is in the two-dimensional structure, the stress-warped whiskers are in a non-warped state, and the stress-warped whiskers are used to detect pressure signals.
[0008] Optionally, when the signal detection sensor is in the three-dimensional structure, the stress-raised whiskers are in a raised state, and the stress-raised whiskers are used to detect temperature signals, humidity signals, and airflow signals.
[0009] Optionally, the sensing whiskers are composed of a multi-walled carbon nanotube dispersion and polyethyleneimine.
[0010] Optionally, the flexible substrate comprises polydimethylsiloxane, and the structure of the flexible substrate is a pyramidal microstructure array.
[0011] Optionally, the composite conductive film includes silver nanowires.
[0012] Secondly, this application discloses a method for fabricating a signal detection sensor with a variable structure, comprising:
[0013] Acquire sensor templates, polydimethylsiloxane, multi-walled carbon nanotube dispersions, polyethyleneimine, and composite conductive films;
[0014] Polydimethylsiloxane was spin-coated onto the sensor template to obtain a flexible substrate with a pyramidal microstructure array;
[0015] Based on the multi-walled carbon nanotube dispersion and the polyethyleneimine, stress-free whiskers and stress-curved whiskers attached to the flexible substrate are obtained.
[0016] The composite conductive film is encapsulated with the stress-free non-warping whiskers attached to the flexible substrate and the flexible substrate to obtain an encapsulated sensor.
[0017] A signal detection sensor is obtained based on the stress-induced warping whiskers attached to the flexible substrate and the encapsulated sensor.
[0018] Optionally, before obtaining the composite conductive film, the following steps are also included:
[0019] Obtaining silver nanowires and polycarbonate plates;
[0020] The process of obtaining the composite conductive thin film includes:
[0021] A silver nanowire ethanol dispersion was obtained based on the described silver nanowires;
[0022] The silver nanowire ethanol dispersion was sprayed onto the polycarbonate plate to obtain the composite conductive film.
[0023] Optionally, obtaining stress-free whiskers and stress-curved whiskers attached to the flexible substrate based on the multi-walled carbon nanotube dispersion and the polyethyleneimine includes:
[0024] The multi-walled carbon nanotube dispersion was diluted with water to obtain a first multi-walled carbon nanotube spraying solution.
[0025] The polyethyleneimine was added to the multi-walled carbon nanotube dispersion to obtain a second multi-walled carbon nanotube spraying solution.
[0026] The first multi-walled carbon nanotube spray liquid and the second multi-walled carbon nanotube spray liquid are sprayed onto the flexible substrate to obtain sensing whiskers attached to the flexible substrate.
[0027] The sensing whiskers are cut to obtain stress-free whiskers and stress-raised whiskers attached to the flexible substrate.
[0028] Optionally, the base length of the pyramid microstructure array is 100 micrometers, and the spacing between the pyramids in the pyramid microstructure array is 100 micrometers.
[0029] Compared with the prior art, this application has the following beneficial effects:
[0030] This application proposes a structurally variable signal detection sensor, comprising a flexible substrate, sensing whiskers, and a composite conductive film. The sensing whiskers include stress-raised whiskers and stress-non-raised whiskers. Specifically, the stress-raised whiskers are connected to the stress-non-raised whiskers, with the stress-non-raised whiskers attached to the flexible substrate. The composite conductive film is bonded to the stress-raised whiskers and the flexible substrate. The stress-raised whiskers are used to raise when subjected to bending or tensile stress, transforming the signal detection sensor from a two-dimensional structure to a three-dimensional structure. Thus, this application switches the structure of the signal detection sensor by adjusting the stress conditions of the stress-raised whiskers, enabling the sensor to detect signals in different dimensions, thereby improving signal detection efficiency. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0032] Figure 1 This is a schematic diagram of the structure of a variable signal detection sensor provided in an embodiment of this application;
[0033] Figure 2 A schematic diagram of stress-warped whiskers in a signal detection sensor with a variable structure provided in an embodiment of this application;
[0034] Figure 3 A flowchart illustrating a method for fabricating a signal detection sensor with a variable structure, as provided in an embodiment of this application;
[0035] Figure 4 A scanning electron microscope (SEM) image of the conductive region in the composite conductive film in a method for fabricating a structurally variable signal detection sensor provided in this application embodiment;
[0036] Figure 5A schematic diagram of the sensing whisker in a method for fabricating a structurally variable signal detection sensor provided in an embodiment of this application;
[0037] Figure 6 Scanning electron microscope (SEM) image of whiskers coated with a first multi-walled carbon nanotube spray liquid in a method for fabricating a structurally variable signal detection sensor provided in this application embodiment;
[0038] Figure 7 The image shows a scanning electron microscope (SEM) image of whiskers coated with a second multi-walled carbon nanotube spray liquid in a method for fabricating a structurally variable signal detection sensor provided in this application embodiment. Detailed Implementation
[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.
[0040] It should be noted that the variable-structure signal detection sensor and its fabrication method provided in this application relate to the field of flexible sensor technology. The above is merely an example and does not limit the application field of the method name provided in this application.
[0041] As mentioned earlier, flexible sensors can detect signals such as pressure, temperature, and humidity, and have broad application prospects in the field of flexible electronics. Currently, there are sensors that can detect pressure signals, and sensors that can detect temperature signals, but because sensors that detect pressure signals cannot simultaneously detect temperature signals, and vice versa, it is necessary to switch to the appropriate sensor when detecting different signals, resulting in low signal detection efficiency. Therefore, improving the efficiency of signal detection is a key issue of concern to those skilled in the art.
[0042] Understandably, the structure of temperature sensors in related technologies is fixed, allowing them to detect pressure signals within a plane only, and the structure of pressure sensors is also fixed, allowing them to detect pressure signals outside a plane only. This results in the need to replace the corresponding sensors when detecting signals in different dimensions, leading to low efficiency in signal detection.
[0043] Therefore, the inventors propose a structurally variable signal detection sensor, which includes a flexible substrate, sensing whiskers, and a composite conductive film. The sensing whiskers include stress-raised whiskers and stress-non-raised whiskers. Specifically, the stress-raised whiskers are connected to the stress-non-raised whiskers, with the stress-non-raised whiskers attached to the flexible substrate. The composite conductive film is bonded to the stress-raised whiskers and the flexible substrate. The stress-raised whiskers are used to raise when subjected to bending or tensile stress, transforming the signal detection sensor from a two-dimensional structure to a three-dimensional structure. Thus, in this application, the structure of the signal detection sensor is switched by adjusting the stress condition of the stress-raised whiskers, enabling the sensor to detect signals in different dimensions, thereby improving signal detection efficiency.
[0044] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0045] See Figure 1 , Figure 1 This is a schematic diagram of the structure of a variable signal detection sensor provided in an embodiment of this application, as shown below. Figure 1 As shown:
[0046] The signal detection sensor includes a flexible substrate 1, sensing whiskers, and a composite conductive film. The sensing whiskers include stress-raised whiskers 2 and stress-non-raised whiskers 3. The composite conductive film includes conductive regions 4 and non-conductive regions 5. Specifically, the stress-raised whiskers 2 and stress-non-raised whiskers 3 are connected and attached to the flexible substrate 1. The conductive regions 4 are attached to the stress-raised whiskers 2, and the non-conductive regions 5 are attached to the stress-non-raised whiskers 3 and the flexible substrate 1. Since the flexible substrate 1 does not have a sensing function, the non-conductive regions 5 are not conductive. The stress-raised whiskers 2 are used to raise when subjected to bending or tensile stress, thus transforming the signal detection sensor from a two-dimensional structure to a three-dimensional structure.
[0047] It should be noted that the stress-raised whiskers 2 and the stress-non-raised whiskers 3 have the same height as the flexible substrate 1. The area of the composite conductive film can be larger than the combined area of the stress-raised whiskers 2, the stress-non-raised whiskers 3, and the flexible substrate 1 to facilitate subsequent encapsulation. In this signal detection sensor, the flexible substrate 1, the stress-non-raised whiskers 3, the conductive region 4, and the non-conductive region 5 are in a fixed state, while the stress-raised whiskers 2 are in a non-fixed state. Understandably, when the stress-raised whiskers 2 are not under stress, they are in a non-raised state, i.e., tightly attached to the conductive region 4, making the signal detection sensor a two-dimensional structure. Since the conductive region 4 attached to the stress-raised whiskers 2 is conductive, in this two-dimensional structure, the stress-raised whiskers 2 can be used to detect pressure signals in a plane, while simultaneously achieving self-protection.
[0048] Furthermore, when the stress-raised whisker 2 is under stress (i.e., bending stress or tensile stress), the stress-raised whisker is in a raised state, that is, away from the conductive region 4. Without relying on the conductivity of the conductive region 4, the signal detection sensor is in a three-dimensional structure. In this three-dimensional structure, the stress-raised whisker 2 in the signal detection sensor can be used to detect out-of-plane temperature signals, humidity signals, and airflow signals, solving the deficiency of related technologies that can only detect signals within or outside a single plane. Among these, in the three-dimensional structure, the stress-raised whisker 2 in the signal detection sensor can also be used to detect out-of-plane stress.
[0049] It should also be noted that in this application, the flexible substrate 1 can be on top, and the composite conductive film can be on the bottom (e.g., ...). Figure 1 (As shown); the flexible substrate 1 can also be located below, and the composite conductive film can be located above. In this way, if the composite conductive film is located below, the stress-curved whiskers 2 will curl upward; if the composite conductive film is located above, the stress-curved whiskers 2 will curl downward.
[0050] like Figure 2 As shown, Figure 2 This is a schematic diagram of a stress-warped whisker in a signal detection sensor with a variable structure, provided as an embodiment of this application. Figure 2 The diagram shows the warping change of the stress-warped whisker 2 when subjected to bending stress and tensile stress. That is, before being subjected to bending stress and tensile stress, the stress-warped whisker 2 is close to the conductive region 4; after being subjected to bending stress and tensile stress, the stress-warped whisker 2 moves away from the conductive region 4.
[0051] It should also be noted that the stress-curved whisker 2 in this application can convert the signal detection sensor from a two-dimensional structure to a three-dimensional structure, or vice versa. In other words, by removing the stress acting on the stress-curved whisker 2, the signal detection sensor can be converted from a three-dimensional structure to a two-dimensional structure, thus improving the flexibility of the signal detection sensor's structure.
[0052] In one feasible embodiment, the sensing whiskers are composed of a multi-walled carbon nanotube dispersion and polyethyleneimine, the composite conductive film includes silver nanowires, and the flexible substrate is made of polydimethylsiloxane (PDMS), the flexible substrate having a pyramidal microstructure array structure. It should be noted that the sensing whiskers can be composed of a flexible substrate and a multi-walled carbon nanotube dispersion sprayed onto the flexible substrate, and a multi-walled carbon nanotube dispersion doped with polyethyleneimine. The flexible composite conductive film is formed by silver nanowires embedded in the surface of PDMS; therefore, the composite conductive film can include both silver nanowires and PDMS.
[0053] As can be seen, this alternative solution proposes a signal detection sensor with a variable structure. By switching the structure of the signal detection sensor, different signals can be detected under different sensor structures, thereby improving the efficiency of signal detection.
[0054] The following describes a method for fabricating a signal detection sensor with a variable structure provided in this application through another embodiment.
[0055] See Figure 3 The figure is a flowchart of a method for fabricating a structurally variable signal detection sensor according to an embodiment of this application. Figure 3 As shown, the method may include:
[0056] S301: Acquire sensor template, polydimethylsiloxane, multi-walled carbon nanotube dispersion, polyethyleneimine, and composite conductive film.
[0057] In this step, polydimethylsiloxane can be a polydimethylsiloxane (PDMS) prepolymer, and the sensor template can be a silicon wafer containing a laser-etched pyramid microstructure array with a base side length of 100 micrometers (μm) and a pyramid spacing of 100 micrometers (μm).
[0058] It should be noted that, prior to obtaining the composite conductive film, this application may also obtain silver nanowires and a polycarbonate plate. In this application, a silver nanowire ethanol dispersion can be obtained from the silver nanowires, and then the silver nanowire ethanol dispersion is sprayed onto a polycarbonate (PC) plate to obtain a composite conductive film with good conductivity.
[0059] Understandably, this application can utilize a polyol method to synthesize silver nanowires. Specifically, firstly, polyvinylpyrrolidone (PVP) is dissolved in glycerol, then silver nitrate is added and the mixture is magnetically stirred and heated. During the heating process, sodium chloride solution is continuously added until silver nanowires are obtained after the reaction. Afterward, the mixture is settled, washed, centrifuged, and dispersed to obtain an ethanol dispersion of silver nanowires. Further, a polycarbonate plate can be placed on a heating stage, and the ethanol dispersion of silver nanowires can be sprayed onto a mask. Subsequently, a layer of polydimethylsiloxane prepolymer is spin-coated and heated to cure. The polydimethylsiloxane prepolymer is then peeled off, and the sprayed silver nanowires are transferred onto the prepolymer to obtain a composite conductive film.
[0060] In one feasible embodiment, 5.86 g of polyvinylpyrrolidone (PVP) is added to 190 mL of glycerol and stirred vigorously at 100 °C for 1 hour to dissolve, forming a homogeneous solution. After the solution cools naturally to 30 °C, 1.58 g of silver nitrate is added with slow stirring, and the mixture is heated to 210 °C for 20 minutes. During the heating process, sodium chloride solution (0.059 g of sodium chloride solution dissolved in 0.5 mL of deionized water and 10 mL of glycerol) can be added at 60 °C. When the solution temperature reaches 210 °C, heating is immediately stopped, and after the reaction is complete, 200 mL of deionized water is added to the solution. The solution is allowed to stand for 12 hours, the supernatant is discarded, and the bottom precipitate is collected to obtain silver nanowires. These nanowires are washed with ethanol, centrifuged, and then redispersed in 60 mL of ethanol to obtain an ethanol dispersion of silver nanowires.
[0061] Furthermore, a 10cm × 10cm polycarbonate plate can be placed on an 80°C heating stage, and then a silver nanowire ethanol dispersion can be sprayed onto a mask. Each pattern unit on the mask is 5mm × 10mm in size, and 50μL of the silver nanowire ethanol dispersion is sprayed onto each pattern unit. Then, 5g of polydimethylsiloxane prepolymer is added and spread out. The polydimethylsiloxane prepolymer is spin-coated at 100rpm for 30s. Finally, it is placed on a 60°C heating stage for 2 hours to cure. The polydimethylsiloxane prepolymer is then peeled off the polycarbonate plate, and the sprayed silver nanowires are transferred onto it to obtain a composite conductive film.
[0062] like Figure 4 As shown, Figure 4 This is a scanning electron microscope (SEM) image of the conductive region in the composite conductive film in a method for fabricating a structurally variable signal detection sensor provided in this application embodiment. Figure 4 This shows a schematic cross-sectional view of the conductive region in the composite conductive film under a scanning electron microscope. Figure 4 The depth of embedding of the silver nanowires into the polydimethylsiloxane substrate is 1 micrometer. It should be noted that... Figure 4Only a portion of the conductive region is shown, intended to characterize the depth at which the silver nanowires are embedded in the polydimethylsiloxane substrate.
[0063] It should be further noted that the data used in the process of obtaining the composite conductive film can be set according to actual needs in practical applications, and no specific limitation is made here. For example, the temperature of the heating stage when spraying silver nanowire ethanol dispersion can be 70-90℃, the size of each pattern unit of the mask can be 3mm×10mm, 4mm×10mm, 5mm×10mm and 6mm×10mm, and the amount of silver nanowire ethanol sprayed on each unit can be 20-100μL. When curing polydimethylsiloxane prepolymer, the temperature of the heating stage can be 50-80℃, and the curing time can be 1-4h.
[0064] S302: Spin-coating polydimethylsiloxane onto the sensor template to obtain a flexible substrate with a pyramidal microstructure array.
[0065] Specifically, in this application, polydimethylsiloxane can be spin-coated onto a sensor template (i.e., a silicon wafer containing a laser-etched pyramid microstructure array) to directly obtain a flexible substrate with a pyramid microstructure array.
[0066] Understandably, in this application, a sacrificial layer can first be spin-coated onto the sensor template, heated and dried, followed by spin-coating of a polydimethylsiloxane prepolymer and heating to cure. Afterward, the cured polydimethylsiloxane prepolymer, along with the sensor template, is immersed in water, and then the polydimethylsiloxane prepolymer film is peeled off to obtain a flexible substrate with a pyramidal microstructure array. It should be noted that the sacrificial layer can be a 5% pullulan solution, which can be redissolved in water. The spin-coating speed of the sacrificial layer can be 300–500 rpm, the spin-coating time can be 20–40 s, the drying temperature can be 50–80℃, and the drying time can be 1–5 min.
[0067] In one feasible implementation, the sensor template is first subjected to hydrophilic treatment at 70W in a plasma cleaner for 3 minutes. Then, 4g of a 5% pullulan solution is dropped and spread onto the sensor template, and spin-coated at 400rpm for 30s, followed by drying on a 60°C heating stage for 3 minutes. After this, 3g of polydimethylsiloxane prepolymer is added, and spin-coated at 300rpm for 30s, followed by curing at 60°C for 2 hours. Finally, the cured polydimethylsiloxane prepolymer, along with the sensor template, is immersed in water for 8 hours. The PDMS film is then peeled off, yielding a flexible substrate with a pyramidal microstructure array.
[0068] It should be noted that the data used in the process of obtaining the flexible substrate described above can be set according to actual needs in practical applications, and no specific limitations are made here. For example: the power of the plasma cleaner can be 50-100W, and the cleaning time can be 1-5 minutes; the amount of pullulan polysaccharide solution added can be 3-5g, the spin coating speed can be 300-500rpm, the spin coating time can be 20-40s, and the drying temperature can be 50-80℃; the mass ratio of polydimethylsiloxane prepolymer can be matrix:curing agent = 8:1, the amount added can be 2-4g, the spin coating speed can be 200-400rpm, the spin coating time can be 20-40s, the drying temperature can be 50-80℃, and the curing time can be 1-4 hours.
[0069] S303: Based on the multi-walled carbon nanotube dispersion and the polyethyleneimine, stress-free whiskers and stress-curved whiskers attached to the flexible substrate are obtained.
[0070] In this step, the multi-walled carbon nanotube (MWCNT) dispersion is first diluted with water to obtain a first MWCNT spray solution. Then, polyethyleneimine (PEI) is added to the MWCNT dispersion to obtain a second MWCNT spray solution. Based on this, the first and second MWCNT spray solutions are sprayed onto a flexible substrate to obtain sensing whiskers attached to the flexible substrate. The sensing whiskers are then cut to obtain stress-free whiskers and stress-raised whiskers attached to the flexible substrate.
[0071] Understandably, the sensing whiskers are cut, that is, partially cut, so that the sensing whiskers that are completely attached to the flexible substrate are cut into stress-free whiskers that are attached to the flexible substrate and stress-free whiskers that are attached to the flexible substrate.
[0072] like Figure 5 As shown, Figure 5 This is a schematic diagram of the sensing whisker used in a method for fabricating a structurally variable signal detection sensor according to an embodiment of this application. Figure 5In the diagram, the pattern within dashed box 5 represents stress-free whiskers attached to a flexible substrate, while the pattern within dashed box 6 represents stress-worn whiskers attached to a flexible substrate. Furthermore, the black, "1"-shaped pattern is obtained by spraying with the first multi-walled carbon nanotube coating liquid, and the gray, "7"-shaped pattern is obtained by spraying with the second multi-walled carbon nanotube coating liquid. It is understandable that the patterns obtained by spraying with the first and second multi-walled carbon nanotube coating liquids can create a temperature difference during sensor detection, allowing the signal detection sensor to better detect signals such as temperature in a three-dimensional structure, thus improving the accuracy of signal detection.
[0073] It should also be noted that, in Figure 5 In this process, the pattern obtained by spraying with the first multi-walled carbon nanotube spray solution can have a length of 8 mm and a width of 1 mm; the pattern obtained by spraying with the second multi-walled carbon nanotube spray solution can have a side length of 8 mm, a top length of 3 mm, and a width of 1 mm. Thus, the first and second multi-walled carbon nanotube spray solutions overlap by 1 mm × 1 mm, ensuring good contact between the sensing whiskers.
[0074] Furthermore, in this application, the first and second multi-walled carbon nanotube (MWCNT) spraying solutions can be prepared. Specifically, a MWCNT dispersion can be diluted with water and stirred thoroughly to obtain the first MWCNT spraying solution (i.e., p-type MWCNT spraying solution); and polyethyleneimine (PEI) can be added to the MWCNT dispersion, diluted with water, and stirred thoroughly to obtain the second MWCNT spraying solution (i.e., n-type MWCNT-PEI spraying solution). It should be noted that the dilution factor of the first MWCNT spraying solution can be 10 to 100 times, the dilution factor of the second MWCNT spraying solution can be 10 to 100 times, and the mass ratio of the MWCNT dispersion to polyethyleneimine in the second MWCNT spraying solution can be 1:10, 1:1, or 10:1.
[0075] In one feasible embodiment, 0.2500 g of a 14 wt% multi-walled carbon nanotube dispersion can be diluted with water to a total mass of 17.5 g, diluted 70 times, and magnetically stirred for 12 h to obtain a first multi-walled carbon nanotube spraying solution. Figure 6 As shown, Figure 6 The image shows a scanning electron microscope (SEM) image of whiskers coated with a first multi-walled carbon nanotube spray solution in a method for fabricating a structurally variable signal detection sensor provided in this application embodiment. Figure 6A schematic diagram of whiskers obtained from a first multi-walled carbon nanotube spray solution applied to a flexible substrate is shown under a scanning electron microscope.
[0076] Furthermore, 0.035 g of polyethyleneimine can be added to 0.2500 g of a 14 wt% multi-walled carbon nanotube dispersion to achieve a mass ratio of 1:1 between the multi-walled carbon nanotube dispersion and polyethyleneimine. Afterward, water is added to a total mass of 17.5 g, diluted 70 times, and magnetically stirred for 12 hours to obtain a second multi-walled carbon nanotube coating solution. Figure 7 As shown, Figure 7 The image shows a scanning electron microscope (SEM) image of whiskers coated with a second multi-walled carbon nanotube spray solution in a method for fabricating a structurally variable signal detection sensor provided in this application embodiment. Figure 7 A schematic diagram of whiskers obtained from a second multi-walled carbon nanotube spray solution applied to a flexible substrate is shown under a scanning electron microscope.
[0077] Based on the first and second multi-walled carbon nanotube (MWC) coating solutions, a two-component sensing unit (i.e., sensing crystal) can be sequentially coated onto a flexible substrate using a mask. The two ends of this two-component sensing unit (i.e., the stress-free whisker portion) are connected by wires. Subsequently, the two-component sensing unit is cut to obtain stress-free whiskers (which remain connected to the flexible substrate) and partially stress-free whiskers (which remain connected to the flexible substrate) attached to the flexible substrate.
[0078] In one feasible implementation, a flexible substrate can be hydrophilically treated in a plasma cleaner at 70W power for 3 minutes. Subsequently, the flexible substrate is placed on a 100°C heating plate, and 400 μL volumes of a first multi-walled carbon nanotube (MWC) coating solution and a second MWC coating solution are sequentially sprayed through a mask to obtain a two-component sensing unit. The two ends of the two-component sensing unit can be connected by copper wires. It should be noted that the plasma cleaner power can be 50–100W, the cleaning time can be 1–5 minutes, the heating plate temperature can be 90–120°C, the first and second MWC coating solutions can be 200–600 μL, and the structural dimensions of the two-component sensing unit can be 3 mm × 8 mm.
[0079] S304: Encapsulate the composite conductive film with the stress-free whiskers attached to the flexible substrate and the flexible substrate to obtain an encapsulated sensor.
[0080] In this step, a polydimethylsiloxane prepolymer is first coated onto a flexible substrate. Then, the coated flexible substrate is bonded to a composite conductive film, and the bonded flexible substrate, the composite conductive film, and the stress-free whiskers attached to the flexible substrate are cured and encapsulated to obtain a packaged sensor. In one feasible embodiment, the flexible substrate and the composite conductive film are bonded face-to-face and then heated and cured on a 60°C heating stage for 2 hours to achieve encapsulation and obtain the packaged sensor. The heating and curing temperature can be 50–80°C, and the curing time can be 1–4 hours.
[0081] S305: A signal detection sensor is obtained based on the stress-induced warping whiskers and the packaged sensor attached to the flexible substrate.
[0082] Understandably, in this application, polydimethylsiloxane prepolymer can be coated onto stress-curved whiskers attached to a flexible substrate. Subsequently, the coated stress-curved whiskers attached to the flexible substrate are bonded to a composite conductive film, and the bonded stress-curved whiskers attached to the flexible substrate are encapsulated with the composite conductive film and the encapsulated sensor to obtain a signal detection sensor. This allows the stress-curved whiskers attached to the flexible substrate to transform the signal detection sensor from a two-dimensional structure to a three-dimensional structure under stress, thereby improving the signal detection efficiency.
[0083] In summary, in this alternative scheme, the structure of the signal detection sensor is switched by adjusting the stress condition of the whiskers, thereby enabling the signal detection sensor to detect signals in different dimensions and thus improving the efficiency of signal detection.
[0084] 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.
[0085] It should be noted that the "first" and "second" in the names such as "first" and "second" (if they exist) mentioned in the embodiments of this application are only used as name identifiers and do not represent the first and second in order.
[0086] The above provides a detailed description of a variable-structure signal detection sensor and its fabrication method provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.
Claims
1. A signal detection sensor with a variable structure, characterized in that, The signal detection sensor includes a flexible substrate, sensing whiskers, and a composite conductive film. The sensing whiskers include stress-raised whiskers and stress-non-raised whiskers. The stress-raised whiskers are connected to the stress-non-raised whiskers. The stress-raised whiskers and the stress-non-raised whiskers are at the same height as the flexible substrate. The stress-non-raised whiskers are attached to the flexible substrate along their horizontal extension direction. The composite conductive film is attached to the stress-raised whiskers, the stress-non-raised whiskers and the flexible substrate. The stress-curved whiskers are used to curl up when subjected to bending or tensile stress, thereby converting the signal detection sensor from a two-dimensional structure to a three-dimensional structure.
2. The signal detection sensor according to claim 1, characterized in that, When the signal detection sensor is in the two-dimensional structure, the stress-raised whiskers are in a non-raised state, and the stress-raised whiskers are used to detect pressure signals.
3. The signal detection sensor according to claim 1, characterized in that, When the signal detection sensor is in the three-dimensional structure, the stress-raised whiskers are in a raised state, and the stress-raised whiskers are used to detect temperature signals, humidity signals, and airflow signals.
4. The signal detection sensor according to claim 1, characterized in that, The sensing whiskers are composed of a multi-walled carbon nanotube dispersion and polyethyleneimine.
5. The signal detection sensor according to claim 1, characterized in that, The flexible substrate comprises polydimethylsiloxane, and the structure of the flexible substrate is a pyramidal microstructure array.
6. The signal detection sensor according to claim 1, characterized in that, The composite conductive film includes silver nanowires.
7. A method for fabricating a signal detection sensor with a variable structure as described in claim 1, characterized in that, include: Acquire sensor templates, polydimethylsiloxane, multi-walled carbon nanotube dispersions, polyethyleneimine, and composite conductive films; Polydimethylsiloxane was spin-coated onto the sensor template to obtain a flexible substrate with a pyramidal microstructure array; Based on the multi-walled carbon nanotube dispersion and the polyethyleneimine, stress-free whiskers and stress-curved whiskers attached to the flexible substrate are obtained.
8. The preparation method according to claim 7, characterized in that, Before obtaining the composite conductive thin film, the following steps are also included: Obtaining silver nanowires and polycarbonate plates; The process of obtaining the composite conductive thin film includes: A silver nanowire ethanol dispersion was obtained based on the described silver nanowires; The silver nanowire ethanol dispersion was sprayed onto the polycarbonate plate to obtain the composite conductive film.
9. The preparation method according to claim 7, characterized in that, The process of obtaining stress-free whiskers and stress-curved whiskers attached to the flexible substrate based on the multi-walled carbon nanotube dispersion and the polyethyleneimine includes: The multi-walled carbon nanotube dispersion was diluted with water to obtain a first multi-walled carbon nanotube spraying solution. The polyethyleneimine was added to the multi-walled carbon nanotube dispersion to obtain a second multi-walled carbon nanotube spraying solution. The first multi-walled carbon nanotube spray liquid and the second multi-walled carbon nanotube spray liquid are sprayed onto the flexible substrate to obtain sensing whiskers attached to the flexible substrate. The sensing whiskers are cut to obtain stress-free whiskers and stress-raised whiskers attached to the flexible substrate.
10. The preparation method according to claim 7, characterized in that, The base side length of the pyramid microstructure array is 100 micrometers, and the spacing between the pyramids in the pyramid microstructure array is 100 micrometers.