A signal amplification device and a method of manufacturing the same

Abstract

The application discloses a signal amplification device and a preparation method thereof, and the preparation method comprises the following steps: preparing a piezoelectric fiber membrane through a coaxial electrospinning method, then soaking the piezoelectric fiber membrane in a PDMS solution, and performing vacuum-assisted soaking, so that the PDMS prepolymer fully penetrates into the pores and fiber gaps of the piezoelectric fiber membrane, and a piezoelectric fiber membrane after PDMS solidification is obtained; gold thin films are uniformly deposited on the front and back surfaces of the piezoelectric fiber membrane after PDMS solidification, conductive composite paste is coated on the surfaces of the gold thin films to form electrode layers, and heating and solidification are performed; flexible wires or conductive cloth are used to reliably connect reserved pad areas of the composite electrodes after solidification, electrode leads are formed, and transparent packaging protective layers are prepared on the upper and lower surfaces of the device with the electrode leads. The application directly realizes amplification of a voltage signal on a physical layer through structural design, can amplify 2-10 times, depends on the number of stacked layers and the number of series connection, and the amplitude of an output signal is significantly improved.

Description

Technical Field

[0001] This invention pertains to signal amplification devices and their manufacturing methods, specifically a signal amplification device and its preparation method. Background Technology

[0002] Piezoelectric pressure / strain sensors, due to their high sensitivity, fast response, and self-powered characteristics, have broad application prospects in health monitoring, human-computer interaction, and IoT sensing. However, miniaturizing and making them flexible to meet the needs of wearable and implantable applications faces fundamental challenges:

[0003] First, there is a trade-off between sensitivity and size. The voltage output of the sensor is related to the effective strain and thickness of the piezoelectric material. Ultra-thinning (<100μm) leads to a decrease in the thickness and strain gradient of the piezoelectric material, resulting in an extremely weak original output voltage signal (typically in the millivolt or even microvolt range).

[0004] Secondly, the signal chain is complex and consumes a lot of power. To detect such weak signals, high-gain, low-noise external operational amplifiers must be used for multi-stage amplification and conditioning. This not only increases the system size, complexity, and design difficulty, but its own power consumption often exceeds that of the sensor, severely limiting its application in low-power scenarios.

[0005] Third, the gain bottleneck of planar structures. Most existing flexible piezoelectric sensors adopt planar structures. To improve output, they mainly rely on connecting multiple units in series to superimpose voltages. However, series connection significantly increases internal resistance, causing the signal to be weakened before readout. Furthermore, they are extremely sensitive to defects in the connecting wires, resulting in low yield.

[0006] Fourth, it has poor anti-interference ability. Weak signals are easily affected by electromagnetic interference when transmitted through long wires, which further deteriorates the signal-to-noise ratio.

[0007] Therefore, there is an urgent need for an innovative sensor architecture that can amplify the output signal directly at the physical structure level in an ultra-thin form, eliminating or greatly simplifying external active amplifier circuits, and achieving high signal-to-noise ratio and high reliability sensing. Summary of the Invention

[0008] Purpose of the invention: In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a signal amplification device with effective mechanical strain increase, and another purpose of this invention is to provide a signal amplification device with reduced output impedance.

[0009] Technical solution: The present invention provides a method for preparing a signal amplification device, comprising the following steps:

[0010] Step 1: Prepare a piezoelectric fiber membrane by coaxial electrospinning, then immerse the piezoelectric fiber membrane in PDMS solution and perform vacuum-assisted immersion to allow the PDMS prepolymer to fully penetrate into the pores and interfibers of the piezoelectric fiber membrane, thus obtaining a PDMS-cured piezoelectric fiber membrane.

[0011] Step 2: On both sides of the PDMS-cured piezoelectric fiber membrane, a gold film is uniformly deposited. The conductive material, uncured liquid silicone elastomer, and n-hexane are uniformly mixed to form a conductive composite slurry. The conductive composite slurry is coated on the surface of the gold film to form an electrode layer with a predetermined pattern and thickness, and then cured by heating.

[0012] Step 3: Use flexible wires or conductive cloth to reliably connect to the reserved pad area of ​​the cured composite electrode to form electrode leads. Prepare a transparent encapsulation protective layer on the upper and lower surfaces of the device with lead-out electrodes.

[0013] Furthermore, in step one, the piezoelectric fiber membrane is a P(VDF-TrFE)@TPU coaxial core-shell fiber membrane.

[0014] Further, in step one, the polydimethylsiloxane solution is prepared by mixing PDMS prepolymer and curing agent at a mass ratio of 9:1, and then diluting with n-hexane until the mass percentage of PDMS is 10%. Vacuum-assisted impregnation allows external mechanical loads to be applied more evenly to the piezoelectric fiber membrane, improving the electromechanical conversion efficiency.

[0015] Furthermore, in step two, the gold thin film is prepared by magnetron sputtering or vacuum evaporation.

[0016] Furthermore, in step two, the thickness of the gold film is 10~25 nm. The gold film forms a good ohmic contact with the piezoelectric material, reducing the contact resistance between the electrode and the active layer, and enhancing the adhesion between the composite electrode and the piezoelectric fiber film.

[0017] Furthermore, in step two, the mass ratio of conductive material to uncured liquid silicone elastomer is 2~3:21:20.

[0018] Furthermore, in step two, the predetermined pattern is L-shaped or serpentine, and the thickness of the electrode layer is 90~100 μm.

[0019] Furthermore, in step three, the heating and curing temperature is 70~80℃, and the time is 2~3 hours.

[0020] Furthermore, in step three, the transparent encapsulation protective layer is a PDMS layer or a thin silicone layer, which provides partial or full encapsulation protection for the electrode and lead connection.

[0021] The signal amplification device of this invention includes a PDMS-cured piezoelectric fiber membrane. A gold thin film, an electrode layer, and a transparent encapsulation protective layer are symmetrically disposed on both sides of the PDMS-cured piezoelectric fiber membrane. Its output impedance is 8.2~10.8 MΩ. The device significantly improves the electrical output performance, mechanical reliability, and environmental stability of the piezoelectric fiber membrane through a unique three-step process of "flexibility enhancement - interface optimization - composite electrode integration."

[0022] Multiple signal amplification devices prepared above are stacked in three dimensions using a flexible adhesive in a "face-to-face" or "back-to-back" manner. During stacking, by designing the electrode lead-out method of each layer, series or parallel electrical connections can be achieved to construct array-type or stacked high-performance devices.

[0023] Fabrication principle: Effective mechanical strain is increased by three-dimensional stacking, output impedance is reduced by intralayer parallel connection, and voltage addition is achieved by controllable interlayer series connection, thus completing the structural amplification of the original piezoelectric signal inside the device.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0025] 1. Through structural design, voltage signals can be amplified directly at the physical level, with an amplification of 2 to 10 times, depending on the number of stacked layers and the number of series connections, resulting in a significant increase in the output signal amplitude;

[0026] 2. Significantly reduces or even eliminates the reliance on external high-gain amplifiers, simplifies signal conditioning circuitry, and reduces overall system power consumption, size, and cost;

[0027] 3. The amplified signal is generated inside the device, with a short transmission path and less susceptibility to environmental electromagnetic interference. The parallel structure reduces thermal noise and collectively improves the signal-to-noise ratio. The improvement factor of the signal-to-noise ratio is related to the number of parallel devices, which conforms to the √N rule.

[0028] 4. The parallel design within the layer provides natural redundancy, and the failure of a single sensitive unit has minimal impact on the overall layer function;

[0029] 5. Achieves high performance with an extremely thin thickness, perfectly adaptable to curved surface application. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the present invention;

[0031] Figure 2 Output voltage response diagram for a single device;

[0032] Figure 3 The output voltage response diagram of the two stacked devices;

[0033] Figure 4 The output voltage response diagram for the three stacked devices is shown. Detailed Implementation

[0034] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Experimental methods not specifically described in the examples are generally performed under standard conditions or as recommended by the manufacturer. PDMS was purchased from Dow Corning, model DC184, and is a two-component kit consisting of liquid components A and B, including PDMS prepolymer and a curing agent.

[0035] Example 1

[0036] A method for manufacturing a signal amplification device includes the following steps:

[0037] Step 1: Take a piece of material and use coaxial electrospinning to transfer the core spinning solution and shell spinning solution into a 10mL syringe respectively. Apply a 10kV voltage through the coaxial needle and simultaneously extrude the shell layer at a volumetric flow rate of 0.6mL / h and the core layer at a volumetric flow rate of 0.3mL / h to prepare a coaxial fiber membrane with a core-shell structure, namely P(VDF-TrFE)@TPU piezoelectric fiber membrane 1, with a thickness of about 50μm and an area of ​​3cm×3cm. Mix the PDMS prepolymer and curing agent at a mass ratio of 9:1 and add n-hexane to dilute to a PDMS mass percentage of 10% to obtain a PDMS mixture. The P(VDF-TrFE) piezoelectric fiber membrane 1 was completely immersed in the PDMS mixture and kept under a vacuum of -0.1 MPa for 30 minutes to ensure that the PDMS precursor was fully wetted into all the pores of the P(VDF-TrFE) piezoelectric fiber membrane 1. The impregnated piezoelectric fiber membrane 1 was slowly pulled out, placed on a horizontal plate, and cured in an oven at 80°C for 2 hours to obtain the PDMS-cured piezoelectric fiber membrane 1.

[0038] Step 2: Fix the piezoelectric fiber membrane 1 onto the sample stage of a magnetron sputtering instrument. Using a high-purity gold target, under an argon atmosphere, and with a sputtering power of 50W, deposit a gold film 2 with a thickness of approximately 25 nm on both sides of the piezoelectric fiber membrane 1 through a photomask. Weigh 2.34 g of acetylene black and add 21 g of Guoyuan liquid silica gel. The ratio of component A to component B is 2:1, where component A is the catalyst and component B is the curing agent. Then add 20 g of n-hexane for dilution and stir at 2000 rpm for 1 hour in a stirrer to form a uniform, viscous black conductive paste. Using an adjustable thickness doctor blade with a blade gap set to 200 μm, uniformly coat the conductive paste onto one side of the gold film 2 through a photomask. Then, transfer it to an 80°C oven for curing for 2 hours to obtain an electrode layer 3 with a thickness of 90 μm. Flip the film and repeat the same operation on the other side, ensuring that the electrode patterns on both sides are aligned vertically.

[0039] Step 3: Take two extremely fine tin-plated copper stranded wires, each approximately 0.1 mm in diameter, and pre-coat one end with a small amount of conductive silver paste. Press and adhere the coated ends to the pre-reserved pad areas on both sides of the film electrode. Heat at 80°C for 30 minutes to allow the silver paste to fully cure, forming a reliable electrical and mechanical connection.

[0040] Step four: After mixing the PDMS prepolymer and curing agent at a ratio of 9:1 and degassing, the mixture is evenly poured onto the device surface and spin-coated at 500 rpm for 30 seconds to form a transparent encapsulation protective layer 4 with a thickness of approximately 100 μm. The transparent encapsulation protective layer 4 is a PDMS layer. It is then cured at 80°C for 2 hours. This transparent encapsulation protective layer 4 completely covers the electrode and lead bonding area, exposing only the lead ends, thus obtaining the signal amplification device.

[0041] like Figure 1 The signal amplification device obtained in this embodiment includes, from bottom to top, a transparent encapsulation protective layer 4, an electrode layer 3, a gold thin film 2, a piezoelectric fiber film 1, another gold thin film 2, an electrode layer 3, and a transparent encapsulation protective layer 4. The thickness of the piezoelectric fiber film 1 is approximately 179 μm, the thickness of the gold thin film 2 is approximately 25 μm, the thickness of the electrode layer 3 is approximately 90 μm, and the thickness of the transparent encapsulation protective layer 4 is approximately 100 μm.

[0042] like Figure 2 The signal amplification device obtained in this embodiment was tested for piezoelectric performance as a linear motor. The results showed that the output voltage was quite considerable after the overall device was fabricated.

[0043] Example 2

[0044] The remaining steps in this embodiment are the same as in Embodiment 1, except that the two signal amplification devices from Embodiment 1 are stacked together, and the electrical output is designed in parallel. Two separate positive leads are soldered together, and the negative leads are soldered together to form a parallel unit. A thin layer of uncured transparent silicone adhesive is applied between the two signal amplification devices, and air bubbles are gently pressed out. The mixture is cured at 80°C for 1 hour. After curing, the device is immersed in PDMS and cured at 80°C for 3 hours.

[0045] like Figure 3 When the signal amplification device obtained in this embodiment is tested for piezoelectric performance, the output signal amplification is more obvious when two devices are stacked compared to a single device.

[0046] Example 3

[0047] The remaining steps in this embodiment are the same as in Embodiment 1, except that the three signal amplification devices from Embodiment 1 are stacked together, and the electrical output is designed in parallel. Three separate positive leads are soldered together, and the negative leads are soldered together to form a parallel unit. A thin layer of uncured transparent silicone adhesive is applied between each layer of signal amplification devices, and air bubbles are gently pressed out. The mixture is then cured at 80°C for 1 hour. After curing, the device is immersed in PDMS and cured at 80°C for 3 hours.

[0048] like Figure 4 When the signal amplification device obtained in this embodiment is tested for piezoelectric performance, the output signal is further amplified when three devices are stacked compared to two devices.

[0049] Example 4

[0050] The remaining steps in this embodiment are the same as in Embodiment 1, except that: four signal amplification devices from Embodiment 1 are stacked, and the electrical output is designed in parallel mode. Four separate positive leads are soldered together, and the negative leads are soldered together to form a parallel unit. A thin layer of uncured transparent silicone adhesive is applied between each layer of signal amplification devices, and air bubbles are gently pressed out. The mixture is cured at 80°C for 1 hour. After curing, the device is immersed in PDMS and cured at 80°C for 3 hours.

[0051] Example 5

[0052] A method for manufacturing a signal amplification device includes the following steps:

[0053] Step 1: Take a P(VDF-TrFE)@TPU piezoelectric fiber membrane 1, approximately 50 μm thick and 3 cm × 3 cm in area, prepared by coaxial electrospinning. Mix PDMS prepolymer and curing agent at a mass ratio of 9:1, and dilute with n-hexane to a PDMS mass percentage of 10%, obtaining a PDMS mixture. Completely immerse the P(VDF-TrFE) piezoelectric fiber membrane 1 in the PDMS mixture and maintain it under a vacuum of -0.1 MPa for 30 minutes to ensure that the PDMS precursor is fully wetted into all pores of the P(VDF-TrFE) piezoelectric fiber membrane 1. Slowly lift and remove the impregnated piezoelectric fiber membrane 1, place it on a horizontal plate, and cure it in an oven at 80°C for 2 hours to obtain the PDMS-cured piezoelectric fiber membrane 1.

[0054] Step 2: Fix the piezoelectric fiber membrane 1 onto the sample stage of a magnetron sputtering instrument. Using a high-purity gold target, under an argon atmosphere and with a sputtering power of 50W, deposit a gold film 2 with a thickness of approximately 10 nm on both sides of the piezoelectric fiber membrane 1 through a photomask. Weigh 2 g of acetylene black and add 21 g of liquid silica gel, with an A:B component ratio of 2:1. Then add 20 g of n-hexane for dilution and stir at 2000 rpm for 1 hour in a stirrer to form a uniform, viscous black conductive paste. Using an adjustable thickness doctor blade with a blade gap set to 200 μm, uniformly coat the conductive paste onto one side of the gold film 2 through a photomask. Then, transfer it to a 70℃ oven for curing for 3 hours to obtain electrode layer 3. Flip the film and repeat the same operation on the other side, ensuring that the electrode patterns on both sides are aligned vertically.

[0055] Step 3: Take two extremely fine tin-plated copper stranded wires, each approximately 0.1 mm in diameter, and pre-coat one end with a small amount of conductive silver paste. Press and adhere the coated ends to the pre-reserved pad areas on both sides of the film electrode. Heat at 80°C for 30 minutes to allow the silver paste to fully cure, forming a reliable electrical and mechanical connection.

[0056] Step four: After mixing the PDMS prepolymer and curing agent at a ratio of 9:1 and degassing, the mixture is evenly poured onto the device surface and spin-coated at 500 rpm for 30 seconds to form a transparent encapsulation protective layer 4 with a thickness of approximately 100 μm. The transparent encapsulation protective layer 4 is a PDMS layer. It is then cured at 80°C for 2 hours. This transparent encapsulation protective layer 4 completely covers the electrode and lead bonding area, exposing only the lead ends.

[0057] Example 6

[0058] A method for manufacturing a signal amplification device includes the following steps:

[0059] Step 1: Take a P(VDF-TrFE)@TPU piezoelectric fiber membrane 1, approximately 50 μm thick and 3 cm × 3 cm in area, prepared by coaxial electrospinning. Mix PDMS prepolymer and curing agent at a mass ratio of 9:1, and dilute with n-hexane to a PDMS mass percentage of 10%, obtaining a PDMS mixture. Completely immerse the P(VDF-TrFE) piezoelectric fiber membrane 1 in the PDMS mixture and maintain it under a vacuum of -0.1 MPa for 30 minutes to ensure that the PDMS precursor is fully wetted into all pores of the P(VDF-TrFE) piezoelectric fiber membrane 1. Slowly lift and remove the impregnated piezoelectric fiber membrane 1, place it on a horizontal plate, and cure it in an oven at 80°C for 2 hours to obtain the PDMS-cured piezoelectric fiber membrane 1.

[0060] Step 2: Fix the piezoelectric fiber membrane 1 onto the sample stage of a magnetron sputtering instrument. Using a high-purity gold target, under an argon atmosphere and with a sputtering power of 50W, deposit a gold film 2 with a thickness of approximately 20 nm on both sides of the piezoelectric fiber membrane 1 through a photomask. Weigh 3 g of acetylene black and add 21 g of liquid silica gel, with an A:B component ratio of 2:1. Then add 20 g of n-hexane for dilution and stir at 2000 rpm for 1 hour in a stirrer to form a uniform, viscous black conductive paste. Using an adjustable thickness doctor blade with a blade gap set to 200 μm, uniformly coat the conductive paste onto one side of the gold film 2 through a photomask. Then, transfer it to an 80℃ oven for curing for 2 hours to obtain the electrode layer 3. Flip the film and repeat the same operation on the other side, ensuring that the electrode patterns on both sides are aligned vertically.

[0061] Step 3: Take two extremely fine tin-plated copper stranded wires, each approximately 0.1 mm in diameter, and pre-coat one end with a small amount of conductive silver paste. Press and adhere the coated ends to the pre-reserved pad areas on both sides of the film electrode. Heat at 80°C for 30 minutes to allow the silver paste to fully cure, forming a reliable electrical and mechanical connection.

[0062] Step four: After mixing the PDMS prepolymer and curing agent at a ratio of 9:1 and degassing, the mixture is evenly poured onto the device surface and spin-coated at 500 rpm for 30 seconds to form a transparent encapsulation protective layer 4 with a thickness of approximately 100 μm. The transparent encapsulation protective layer 4 is a thin layer of silicone. It is then cured at 80°C for 2 hours. This transparent encapsulation protective layer 4 completely covers the electrode and lead bonding area, exposing only the lead ends.

[0063] Comparative Example 1

[0064] The remaining steps of this comparative example are the same as in Example 1, except that the gold film 2 is omitted, and a mixture of silicone and acetylene black is directly coated. The results showed that the signal output was not very stable.

[0065] Comparative Example 2

[0066] The remaining steps in this comparative example are the same as in Example 1, except that the thickness of electrode layer 3 is replaced with 120 μm. The results showed that electrode layer 3 was difficult to cure and its conductivity was unstable.

[0067] Comparative Example 3

[0068] The remaining steps of this comparative example were the same as in Example 1, except that acetylene black was replaced with graphene. The results showed that the curing effect was poor and the stability was also poor.

[0069] Comparative Example 4

[0070] The remaining steps of this comparative example are the same as those in Example 1, except that the P(VDF-TrFE)@TPU piezoelectric fiber film 1 is replaced with P(VDF-CTFE)@TPS. The results showed that the piezoelectric output of the replaced device was significantly lower than that of the previous fiber film, the stretchability of the TPS was also poor, and due to its relatively high modulus, the overall adhesion was also poor.

Claims

1. A method for manufacturing a signal amplification device, characterized in that, Includes the following steps: Step 1: Prepare piezoelectric fiber membrane (1) by coaxial electrospinning, then immerse the piezoelectric fiber membrane (1) in PDMS solution and perform vacuum-assisted immersion so that the PDMS prepolymer can fully penetrate into the pores and fiber gaps of the piezoelectric fiber membrane (1) to obtain the PDMS-cured piezoelectric fiber membrane (1). Step 2: On both sides of the PDMS-cured piezoelectric fiber membrane (1), a gold film (2) is uniformly deposited. The conductive material, uncured liquid silicone elastomer, and n-hexane are uniformly mixed to form a conductive composite slurry. The conductive composite slurry is coated on the surface of the gold film (2) to form an electrode layer (3) with a predetermined pattern and thickness. The layer is then heated and cured. Step 3: Use flexible wires or conductive cloth to reliably connect to the reserved pad area of ​​the cured composite electrode to form electrode leads. Prepare a transparent encapsulation protective layer (4) on the upper and lower surfaces of the device with lead-out electrodes.

2. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step one, the piezoelectric fiber membrane (1) is a P(VDF-TrFE)@TPU coaxial core-shell fiber membrane.

3. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step one, the polydimethylsiloxane solution is prepared by mixing PDMS prepolymer and curing agent at a mass ratio of 9:1, and then adding n-hexane to dilute it to a mass percentage of 10% for PDMS.

4. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step two, the gold thin film (2) is prepared by magnetron sputtering or vacuum evaporation.

5. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step two, the thickness of the gold thin film (2) is 10~25nm.

6. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step two, the mass ratio of conductive material to uncured liquid silicone elastomer is 2~3:21:

20.

7. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step two, the predetermined pattern is L-shaped or serpentine, and the thickness of the electrode layer (3) is 90~100 μm.

8. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step three, the heating and curing temperature is 70~80℃, and the time is 2~3 hours.

9. The method for manufacturing a signal amplification device according to claim 1, characterized in that: In step three, the transparent encapsulation protective layer (4) is a PDMS layer or a thin silicone layer.

10. A signal amplification device obtained by the preparation method according to any one of claims 1 to 9, characterized in that: The piezoelectric fiber membrane (1) is cured with PDMS. A gold thin film (2), an electrode layer (3) and a transparent encapsulation protective layer (4) are symmetrically arranged on both sides of the piezoelectric fiber membrane (1) after curing with PDMS. Its output impedance is 8.2~10.8 MΩ.

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