Suspended gate transistor type sensitivity-adjustable flexible pressure sensor and preparation method thereof

Abstract

The invention discloses a suspended gate transistor type sensitivity-adjustable flexible pressure sensor and a preparation method thereof. The suspended gate transistor type sensitivity-adjustable flexible pressure sensor comprises a flexible electrode substrate, a semiconductor layer and a pressure sensitive layer serving as a gate, the flexible electrode substrate comprises an active drain electrode and a conductive channel; the semiconductor layer comprises an active layer and a gasket, and the active layer completely covers the source-drain electrode and the conductive channel and is in physical contact with the source-drain electrode; the gaskets are arranged on the active layer, and the gaskets are correspondingly arranged on the two sides of the conductive channel; the pressure sensitive layer is located on the gasket to form a suspended gate structure; when the flexible pressure sensor is subjected to external pressure, the pressure sensitive layer deforms, and the charge quantity of the active layer is changed to realize sensitive detection of the external pressure; the sensitivity of the flexible pressure sensor is adjusted by adjusting source-drain voltage and grid voltage; the flexible pressure sensor has the advantages of low cost, simple process and the like, and can be widely applied to the field of flexible pressure sensors.

Description

Technical Field

[0001] The present invention belongs to the technical field of pressure sensors, and in particular relates to a floating gate transistor-type flexible pressure sensor with adjustable sensitivity and a preparation method thereof. Background Art

[0002] Pressure sensor technology is widely used in many fields, including wearable devices, industrial automation, medical health monitoring and consumer electronics. By sensing the physical pressure applied by the outside world, these force changes are converted into electrical signals to help devices monitor the environment or the user's physiological condition in real time. In wearable devices, pressure sensors can detect the user's vital signs such as breathing and gait; in industrial automation, they are used for precise load and pressure control; in modern medical equipment, pressure sensors are also used to monitor patients' key health parameters such as blood pressure and breathing in real time. With the rise of flexible electronics and IoT devices, pressure sensor technology is also constantly improving to meet the requirements of increasingly complex application scenarios for sensitivity, accuracy, response time and working stability.

[0003] The current mainstream pressure sensor types include piezoelectric, piezoresistive and capacitive. The sensitivity of these devices is usually determined during the design and manufacturing stage, and it is difficult to adjust them during actual use, which limits their application in fields such as medical health monitoring and flexible electronic devices. At present, there are a lot of studies on improving the performance of pressure sensors by constructing microstructures (such as pyramidal, columnar, porous structures, etc.), but these processes often have problems such as high complexity, high equipment prices and high energy consumption. In addition, most existing flexible pressure sensors have insufficient sensitivity and limited detection range, making it difficult to effectively identify weak physiological signals. Therefore, it is necessary to provide a new type of pressure sensor that can take into account high sensitivity, wide detection range and simplified manufacturing process. Summary of the invention

[0004] Purpose of the invention: In order to solve the problem that the sensitivity of existing pressure sensors is difficult to adjust during actual use, and to solve the problems of high process complexity and limited detection range of existing pressure sensors, the present invention proposes a suspended gate transistor-type flexible pressure sensor with adjustable sensitivity and a preparation method thereof. By adjusting the gate voltage and the source-drain voltage, a new pressure sensor with high sensitivity, wide detection range and simplified manufacturing process can be achieved without changing the sensor material.

[0005] Technical solution: A flexible pressure sensor with adjustable sensitivity of a floating gate transistor type, comprising: a flexible electrode substrate, a semiconductor layer and a pressure sensitive layer as a gate; the flexible electrode substrate comprises a source-drain electrode and a conductive channel; the semiconductor layer comprises an active layer and a gasket, the active layer completely covers the source-drain electrode and the conductive channel, and is in physical contact with the source-drain electrode; the gasket is arranged on the active layer, and the gasket is correspondingly arranged on both sides of the conductive channel; the pressure sensitive layer is located on the gasket to form a floating gate structure;

[0006] When the flexible pressure sensor is subjected to external pressure, the pressure sensitive layer deforms, changing the carrier mobility of the active layer, thus realizing sensitive detection of external pressure.

[0007] The sensitivity of the flexible pressure sensor can be adjusted by adjusting the source-drain voltage and the gate voltage.

[0008] Furthermore, the flexible electrode substrate further comprises: a flexible base, and the source-drain electrodes are embedded in the flexible base to form the flexible electrode substrate.

[0009] Furthermore, the active layer is a poly(3-hexylthiophene) film obtained by self-assembly.

[0010] Furthermore, the gasket is made of polydimethylsiloxane material.

[0011] Furthermore, the pressure sensitive layer is an ion gel layer.

[0012] Furthermore, it also includes a packaging layer, wherein the packaging layer covers the pressure sensitive layer.

[0013] The present invention discloses a method for preparing a suspended gate transistor-type flexible pressure sensor with adjustable sensitivity, comprising the following steps:

[0014] Step 1: Attach a polyimide mask to a glass substrate, then apply a silver nanowire dispersion dropwise, and after curing, remove the polyimide mask to form source and drain electrodes and a transistor conductive channel;

[0015] Step 2: Mix the main agent dimethylsiloxane and the cross-linking agent, spin-coat them on the source and drain electrodes and heat and cure them to form a flexible electrode substrate;

[0016] Step 3: dissolving poly(3-hexylthiophene) in toluene and dropping it on the water surface to form a nanofilm, and transferring the formed nanofilm to the source and drain electrodes to completely cover the conductive channel to form an active layer;

[0017] Step 4: prepare a polydimethylsiloxane gasket, cut it into small pieces, and place it on the active layer, and the gasket is correspondingly placed on both sides of the conductive channel;

[0018] Step 5: Mix the polymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone, spin-coat them on the gasket, and heat and cure them to form a pressure-sensitive layer;

[0019] Step 6: Mix the main agent dimethylsiloxane and the cross-linking agent, spin-coat them into an encapsulation layer, place them above the pressure sensitive layer, and cover the ion gel.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0021] (1) The present invention designs a floating gate transistor structure so that the gate voltage and the source-drain voltage can control the sensitivity of the sensor respectively. The floating gate design not only improves the detection accuracy of the sensor under different pressures, but also can dynamically control the sensitivity of the sensor by independently adjusting the gate voltage and the source-drain voltage. In this way, the pressure sensor of the present invention can be flexibly adapted to a variety of application scenarios, and the accuracy and sensitivity can be optimized without changing the material and microstructure.

[0022] (2) The present invention further enhances the stability and durability of the device by designing the encapsulation layer, making it suitable for high-demand applications in flexible electronic devices and wearable devices;

[0023] (3) The method of the present invention has the advantages of low cost and simple process, and can be widely used in the field of flexible pressure sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of a suspended gate transistor-type flexible pressure sensor with adjustable sensitivity proposed by the present invention;

[0025] Figure 2 A flexible pressure sensor with adjustable sensitivity and a suspended gate transistor type proposed by the present invention and its dynamic response diagram;

[0026] Figure 3 A schematic diagram of the response of a suspended gate transistor-type flexible pressure sensor with adjustable sensitivity to different pressures proposed by the present invention;

[0027] Figure 4 Schematic diagram of the effect of source-drain voltage on sensitivity;

[0028] Figure 5 Schematic diagram of the effect of bias voltage on sensitivity. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the following will further illustrate a floating gate transistor-type flexible pressure sensor with adjustable sensitivity and a preparation method thereof proposed in the present invention in combination with the accompanying drawings and embodiments.

[0030] Embodiment 1:

[0031] This embodiment proposes a flexible pressure sensor with adjustable sensitivity of a suspended gate transistor. Figure 1 As shown, it mainly includes: a flexible electrode substrate, a semiconductor layer and a pressure-sensitive layer; in the flexible electrode substrate, source and drain electrodes are formed by silver nanowires, the semiconductor layer is self-assembled to obtain a uniform thin film, and then transferred between the source and drain electrodes, and ion gel is used as the pressure-sensitive layer; in this embodiment, the flexible electrode substrate and the semiconductor layer are covered with a gate material composed of ion gel to form a suspended gate structure, and the suspended gate structure is isolated from the semiconductor layer by the ion gel, and gate control operation is realized in a non-contact state to improve the adjustability of sensitivity.

[0032] Now combined Figure 1 , the structure of the flexible pressure sensor proposed in this embodiment is further described. The flexible electrode substrate includes a flexible base and a source-drain electrode; the semiconductor layer includes an active layer covering the source-drain electrode and a gasket built on the active layer, and the pressure sensitive layer is located on the gasket. This embodiment optimizes the pressure conduction path by reasonably designing the physical contact between the source-drain electrode and the active layer, and combining the gasket. When the sensor is subjected to external pressure, the pressure sensitive layer is deformed, and then the charge of the active layer is changed to achieve sensitive detection of external pressure.

[0033] This embodiment also designs a packaging layer, such as Figure 2 As shown in FIG. 1 , the encapsulation layer not only reduces the dynamic response time of the device, but also improves the stability and durability of the device (eg Figure 3 As shown), it is suitable for various skin-like smart electronic devices. Figure 4 and Figure 5 The effects of the source-drain voltage and the bias voltage on the sensitivity are described respectively. It can be seen that the present embodiment can achieve the adjustability of the sensitivity by adjusting the source-drain voltage and the gate voltage. It has high sensitivity, low power consumption and good flexibility, and is suitable for pressure sensing applications in the field of wearable devices and flexible electronics.

[0034] In this embodiment, the flexible substrate and the encapsulation layer are made of polydimethylsiloxane (PDMS), but are not limited to polydimethylsiloxane (PDMS). The mass ratio of the main agent dimethylsiloxane to the cross-linking agent selected for the flexible substrate is 10:1, and the mass ratio of the main agent dimethylsiloxane to the cross-linking agent selected for the encapsulation layer is 20:1.

[0035] In this embodiment, the material of the source and drain electrodes is silver nanowire material, but is not limited to silver nanowire material. The source and drain electrodes are embedded in polydimethylsiloxane (PDMS) to prepare an AgNWs / PDMS integrated substrate.

[0036] In this embodiment, the active layer is made of poly(3-hexylthiophene) (P3HT) material, but is not limited to poly(3-hexylthiophene) (P3HT) material.

[0037] In this embodiment, the pressure sensitive layer adopts ion gel, which is a mixture of polymer P (VDF-HFP) and electrolyte solution [EMIM] [TFSI], but is not limited to ion gel.

[0038] Embodiment 2:

[0039] This embodiment proposes a method for preparing a floating gate transistor-type flexible pressure sensor with adjustable sensitivity proposed in Embodiment 1, which mainly includes the following steps:

[0040] Step 1: Prepare source and drain electrodes: stick a polyimide mask on a glass substrate, then drip-coat 0.5wt% of silver nanowire dispersion, heat continuously at 50°C, repeat the drip coating three times, cure at 70°C for 20 minutes, and tear off the polyimide mask to form source and drain electrodes and a transistor conductive channel.

[0041] Step 2: Prepare a flexible substrate: prepare polydimethylsiloxane (PDMS) with a mass ratio of main agent dimethylsiloxane and cross-linking agent of 10:1, leave it for 30 minutes until the bubbles disappear completely, spin coat it on the source and drain electrodes prepared in step 1, and heat it at 90°C for 1 hour to completely cure the polydimethylsiloxane (PDMS) to form a flexible substrate.

[0042] Step 3: Prepare the active layer: Dissolve poly(3-hexylthiophene) (P3HT) in toluene to form a polymer solution, then drop it onto the water surface. Since toluene is immiscible with water, the polymer solution will diffuse rapidly on the water surface, thus self-assembling into a poly(3-hexylthiophene) (P3HT) nanofilm at the water / air interface. Then transfer the poly(3-hexylthiophene) (P3HT) nanofilm to the source and drain electrodes in (2), completely covering the channel to form an efficient conductive channel, and dry the water to form an active layer.

[0043] Step 4: Prepare gaskets: prepare polydimethylsiloxane (PDMS) with a mass ratio of 10:1 between the main agent dimethylsiloxane and the cross-linking agent, place it for 30 minutes until the bubbles disappear completely, then spin-coat it on a glass substrate, heat it at 90°C for 1 hour to completely cure the polydimethylsiloxane (PDMS), cut it into 0.4 cm × 0.2 cm pieces, and transfer it to both sides of the conductive channel in (3), with a gasket spacing of 0.3 cm.

[0044] Step 5: Preparation of pressure-sensitive layer: Mix copolymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone in a mass ratio of 1:4:7, heat and stir at 70°C for 2 h to allow the ionic liquid to be evenly dispersed in the gaps of the copolymer, and after the bubbles disappear completely, spin coat on a glass substrate, heat and cure at 70°C for 24 h, cut into 1 cm × 0.2 cm pieces and transfer to the gasket built in (4). The ionic gel should be suspended above the conductive channel and should not contact the active layer or electrode to form a pressure-sensitive layer.

[0045] Step 6: Prepare encapsulation layer: prepare polydimethylsiloxane (PDMS) with a mass ratio of 20:1 between the main agent dimethylsiloxane and the cross-linking agent, leave it for 30 minutes until the bubbles disappear completely, then spin-coat it on a glass substrate, heat it at 90°C for 1 hour to completely cure the PDMS, spin-coat it into an encapsulation layer, cut it into 0.8 cm × 0.2 cm pieces, and place it on the ion gel prepared in (5). The encapsulation layer does not completely cover the pressure sensitive layer to improve the stability and recycling ability of the device.

[0046] Embodiment 3:

[0047] This embodiment provides a method for preparing a floating gate transistor-type flexible pressure sensor with adjustable sensitivity, comprising the following steps:

[0048] (1) A polyimide mask is attached to a glass substrate, and then 0.5 wt % of a silver nanowire dispersion is drop-coated, heated continuously at 50° C., and the drop-coating is repeated three times. The polyimide mask is cured at 70° C. for 20 min, and the polyimide mask is removed to form source and drain electrodes and a transistor conductive channel.

[0049] (2) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred in a mass ratio of 10:1, and the bubble-free PDMS was spin-coated on the prepared source and drain electrodes at 500 rpm, heated and cured at 90°C for 1 h, and the cured PDMS / AgNWs were torn off to obtain a flexible and stretchable source and drain electrode.

[0050] (3) Take a small amount of 10 mg / ml P3HT toluene solution and drop it on a calm water surface. After the solvent evaporates, the P3HT self-assembled film floats on the water surface and is transferred to the flexible electrode. It can be used after it is naturally dried.

[0051] (4) PDMS (the mass ratio of the main agent dimethylsiloxane to the auxiliary agent cross-linking agent is 10:1) gaskets of 0.4 cm × 0.3 cm are attached to both sides of the source and drain channels, and the distance between the two gaskets is 0.3 cm.

[0052] (5) The copolymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone were mixed in a mass ratio of 1:4:7, heated and stirred at 70°C for 2 h to allow the ionic liquid to be evenly dispersed in the gaps of the copolymer. After the bubbles completely disappeared, the mixture was spin-coated on a glass substrate at 500 rpm, heated and cured at 70°C for 24 h, cut into 1 cm × 0.3 cm pieces and transferred to a gasket. The ionic gel should be suspended above the conductive channel and should not come into contact with the active layer and the electrode.

[0053] (6) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred at a mass ratio of 20:1, and spin-coated on the glass substrate at 500 rpm using a coating machine, heated and cured at 90°C for 1 h, cut into 0.8 cm × 0.3 cm sizes, and then transferred to the ion gel to completely cover the ion gel above the channel.

[0054] (7) The device was fixed on a 6-inch probe station, a voltage of -0.5 V was applied to the source and drain electrodes, and different mechanical external forces were applied.

[0055] The pressure sensor prepared according to the above steps has a low pressure range sensitivity of 0.1859 kPa -1 , high pressure range sensitivity is 1.3769kPa -1 .

[0056] Embodiment 4:

[0057] This embodiment provides a method for preparing a floating gate transistor-type flexible pressure sensor with adjustable sensitivity, comprising the following steps:

[0058] (1) A polyimide mask is attached to a glass substrate, and then 0.5 wt % of a silver nanowire dispersion is drop-coated, heated continuously at 50° C., and the drop-coating is repeated three times. The polyimide mask is cured at 70° C. for 20 min, and the polyimide mask is removed to form source and drain electrodes and a transistor conductive channel.

[0059] (2) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred evenly in a mass ratio of 10:1, and the bubble-free PDMS was spin-coated on the prepared source and drain electrodes at 500 rpm, heated and cured at 90°C for 1 h, and the cured PDMS / AgNWs were torn off to obtain a flexible and stretchable source and drain electrode.

[0060] (3) Take a small amount of 10 mg / ml P3HT toluene solution and drop it on a calm water surface. After the solvent evaporates, the P3HT self-assembled film floats on the water surface and is transferred to the flexible electrode. It can be used after it is naturally dried.

[0061] (4) Attach 0.4 cm × 0.3 cm polyimide gaskets (the mass ratio of the main agent dimethylsiloxane to the auxiliary agent cross-linking agent is 10:1) on both sides of the source and drain channels, with a distance of 0.3 cm between the two gaskets.

[0062] (5) The copolymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone were mixed in a mass ratio of 1:4:7, heated and stirred at 70°C for 2 h to allow the ionic liquid to be evenly dispersed in the gaps of the copolymer. After the bubbles completely disappeared, the mixture was spin-coated on a glass substrate at 500 rpm, heated and cured at 70°C for 24 h, cut into 1 cm × 0.3 cm pieces and transferred to a gasket. The ionic gel should be suspended above the conductive channel and should not come into contact with the active layer and the electrode.

[0063] (6) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred in a mass ratio of 20:1, and spin-coated on a glass substrate at 500 rpm using a coating machine, heated and cured at 90°C for 1 h, cut into 0.8 cm × 0.3 cm sizes, and then transferred to the ion gel to completely cover the ion gel above the channel.

[0064] (7) The device was fixed on a probe station, a voltage of -1.0 V was applied to the source and drain electrodes, and different mechanical external forces were applied.

[0065] The pressure sensor prepared according to the above steps has a low pressure range sensitivity of 0.3931 kPa. -1 , high pressure range sensitivity is 2.1111kPa -1 .

[0066] Embodiment 5:

[0067] This embodiment provides a method for preparing a floating gate transistor-type flexible pressure sensor with adjustable sensitivity, comprising the following steps:

[0068] (1) A polyimide mask is attached to a glass substrate, and then 0.5 wt % of a silver nanowire dispersion is drop-coated, heated continuously at 50° C., and the drop-coating is repeated three times. The polyimide mask is cured at 70° C. for 20 min, and the polyimide mask is removed to form source and drain electrodes and a transistor conductive channel.

[0069] (2) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent are mixed and stirred evenly in a mass ratio of 10:1, and the bubble-free polydimethylsiloxane is spin-coated on the prepared source and drain electrodes at 500 rpm, heated and cured at 90°C for 1 h, and the cured PDMS / AgNWs are torn off to obtain a flexible and stretchable source and drain electrode.

[0070] (3) Take a small amount of 10 mg / ml P3HT toluene solution and drop it on a calm water surface. After the solvent evaporates, the P3HT self-assembled film floats on the water surface and is transferred to the flexible electrode. It can be used after it is naturally dried.

[0071] (4) Attach 0.4 cm × 0.3 cm polyimide gaskets (the mass ratio of the main agent dimethylsiloxane to the auxiliary agent cross-linking agent is 10:1) on both sides of the source and drain channels, with a distance of 0.3 cm between the two gaskets.

[0072] (5) The copolymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone were mixed in a mass ratio of 1:4:7, heated and stirred at 70°C for 2 h to allow the ionic liquid to be evenly dispersed in the gaps of the copolymer. After the bubbles completely disappeared, the mixture was spin-coated on a glass substrate at 500 rpm, heated and cured at 70°C for 24 h, cut into 1 cm × 0.3 cm pieces and transferred to a gasket. The ionic gel should be suspended above the conductive channel and should not come into contact with the active layer and the electrode.

[0073] (6) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred in a mass ratio of 20:1, and spin-coated on a glass substrate at 500 rpm using a coating machine, heated and cured at 90°C for 1 h, cut into 0.8 cm × 0.3 cm sizes, and then transferred to the ion gel to completely cover the ion gel above the channel.

[0074] (7) The device was fixed on a probe station, a voltage of -1.5 V was applied to the source and drain electrodes, and different mechanical external forces were applied.

[0075] The pressure sensor prepared according to the above steps has a low pressure range sensitivity of 0.5189 kPa -1 , high pressure range sensitivity is 3.3132kPa -1 .

[0076] Embodiment 6:

[0077] This embodiment provides a method for preparing a floating gate transistor-type flexible pressure sensor with adjustable sensitivity, comprising the following steps:

[0078] (1) A polyimide mask is attached to a glass substrate, and then 0.5 wt % of a silver nanowire dispersion is drop-coated, heated continuously at 50° C., and the drop-coating is repeated three times. The polyimide mask is cured at 70° C. for 20 min, and the polyimide mask is removed to form source and drain electrodes and a transistor conductive channel.

[0079] (2) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred in a mass ratio of 10:1, and the bubble-free polydimethylsiloxane was spin-coated on the prepared source and drain electrodes at 500 rpm, heated and cured at 90°C for 1 h, and the cured PDMS / AgNWs were torn off to obtain a flexible and stretchable source and drain electrode.

[0080] (3) Take a small amount of 10 mg / ml P3HT toluene solution and drop it on a calm water surface. After the solvent evaporates, the P3HT self-assembled film floats on the water surface and is transferred to the flexible electrode. It can be used after it is naturally dried.

[0081] (4) Attach 0.4 cm × 0.3 cm polyimide gaskets (the mass ratio of the main agent dimethylsiloxane to the auxiliary agent cross-linking agent is 10:1) on both sides of the source and drain channels, with a distance of 0.3 cm between the two gaskets.

[0082] (5) The copolymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone were mixed in a mass ratio of 1:4:7, heated and stirred at 70°C for 2 h to allow the ionic liquid to be evenly dispersed in the gaps of the copolymer. After the bubbles completely disappeared, the mixture was spin-coated on a glass substrate at 500 rpm, heated and cured at 70°C for 24 h, cut into 1 cm × 0.3 cm pieces and transferred to a gasket. The ionic gel should be suspended above the conductive channel and should not come into contact with the active layer and the electrode.

[0083] (6) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred at a mass ratio of 20:1, and spin-coated on the glass substrate at 500 rpm using a coating machine, heated and cured at 90°C for 1 h, cut into 0.8 cm × 0.3 cm sizes, and then transferred to the ion gel to completely cover the ion gel above the channel.

[0084] (7) The device was fixed on a probe station, a voltage of -0.5 V was applied to the source and drain electrodes, while the bias voltage was -0.5 V, and different mechanical external forces were applied.

[0085] The pressure sensor prepared according to the above steps has a low pressure range sensitivity of 0.4122 kPa -1 , high pressure range sensitivity is 1.9814kPa -1 .

[0086] Embodiment 7:

[0087] This embodiment provides a method for preparing a floating gate transistor-type flexible pressure sensor with adjustable sensitivity, comprising the following steps:

[0088] (1) A polyimide mask is attached to a glass substrate, and then 0.5 wt % of a silver nanowire dispersion is drop-coated, heated continuously at 50° C., and the drop-coating is repeated three times. The polyimide mask is cured at 70° C. for 20 min, and the polyimide mask is removed to form source and drain electrodes and a transistor conductive channel.

[0089] (2) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred in a mass ratio of 10:1, and the bubble-free polydimethylsiloxane was spin-coated on the prepared source and drain electrodes at 500 rpm, heated and cured at 90°C for 1 h, and the cured PDMS / AgNWs were torn off to obtain a flexible and stretchable source and drain electrode.

[0090] (3) Take a small amount of 10 mg / ml P3HT toluene solution and drop it on a calm water surface. After the solvent evaporates, the P3HT self-assembled film floats on the water surface and is transferred to the flexible electrode. It can be used after it is naturally dried.

[0091] (4) Attach 0.4 cm × 0.3 cm polyimide gaskets (the ratio of main agent dimethylsiloxane to auxiliary agent cross-linking agent is 10:1) on both sides of the source and drain channels, with a distance of 0.3 cm between the two gaskets.

[0092] (5) The copolymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone were mixed in a mass ratio of 1:4:7, heated and stirred at 70°C for 2 h to allow the ionic liquid to be evenly dispersed in the gaps of the copolymer. After the bubbles completely disappeared, the mixture was spin-coated on a glass substrate at 500 rpm, heated and cured at 70°C for 24 h, cut into 1 cm × 0.3 cm pieces and transferred to a gasket. The ionic gel should be suspended above the conductive channel and should not come into contact with the active layer and the electrode.

[0093] (6) The main agent dimethylsiloxane and the auxiliary agent cross-linking agent were mixed and stirred at a mass ratio of 20:1, and spin-coated on the glass substrate at 500 rpm using a coating machine, heated and cured at 90°C for 1 h, cut into 1 cm × 0.3 cm sizes, and then transferred to the ion gel to completely cover the ion gel above the channel.

[0094] (7) The device was fixed on a probe station, a voltage of -0.5 V was applied to the source and drain electrodes, while the bias voltage was -1.0 V, and different mechanical external forces were applied.

[0095] The pressure sensor prepared according to the above steps has a low pressure range sensitivity of 0.9066 kPa -1 , high pressure range sensitivity is 2.4922kPa -1 .

Claims

1. A flexible pressure sensor with adjustable sensitivity of a suspended gate transistor, characterized in that: include: A flexible electrode substrate, a semiconductor layer, and a pressure-sensitive layer as a gate; The flexible electrode substrate includes source and drain electrodes and a conductive channel; The semiconductor layer includes an active layer and a gasket, wherein the active layer completely covers the source-drain electrode and the conductive channel and is in physical contact with the source-drain electrode; the gasket is arranged on the active layer, and the gasket is correspondingly arranged on both sides of the conductive channel; the pressure sensitive layer is located on the gasket to form a floating gate structure; When the flexible pressure sensor is subjected to external pressure, the pressure sensitive layer deforms, changing the carrier mobility of the active layer, thus realizing sensitive detection of external pressure. The sensitivity of the flexible pressure sensor can be adjusted by adjusting the source-drain voltage and the gate voltage.

2. The floating gate transistor-type flexible pressure sensor with adjustable sensitivity according to claim 1, characterized in that: The flexible electrode substrate further comprises: a flexible base, and the source-drain electrodes are embedded in the flexible base to form the flexible electrode substrate.

3. The floating gate transistor-type flexible pressure sensor with adjustable sensitivity according to claim 1, characterized in that: The active layer is a poly(3-hexylthiophene) film obtained by self-assembly.

4. The floating gate transistor type flexible pressure sensor with adjustable sensitivity according to claim 1, characterized in that: The gasket is made of polydimethylsiloxane material.

5. The floating gate transistor-type flexible pressure sensor with adjustable sensitivity according to claim 1, characterized in that: The pressure sensitive layer is an ion gel layer.

6. The floating gate transistor-type flexible pressure sensor with adjustable sensitivity according to claim 1, characterized in that: The invention also comprises a packaging layer, wherein the packaging layer covers the pressure sensitive layer.

7. A method for preparing a flexible pressure sensor with adjustable sensitivity of a floating gate transistor, characterized in that: The following steps are involved: Step 1: Attach a polyimide mask to a glass substrate, then apply a silver nanowire dispersion dropwise, and after curing, remove the polyimide mask to form source and drain electrodes and a transistor conductive channel; Step 2: Mix the main agent dimethylsiloxane and the cross-linking agent, spin-coat them on the source and drain electrodes and heat and cure them to form a flexible electrode substrate; Step 3: dissolving poly(3-hexylthiophene) in toluene and dropping it on the water surface to form a nanofilm, and transferring the formed nanofilm to the source and drain electrodes to completely cover the conductive channel to form an active layer; Step 4: prepare a polydimethylsiloxane gasket, cut it into small pieces, and place it on the active layer, and the gasket is correspondingly placed on both sides of the conductive channel; Step 5: Mix the polymer P(VDF-HFP), ionic liquid [EMIM][TFSI] and acetone, spin-coat them on the gasket, and heat and cure them to form a pressure-sensitive layer; Step 6: Mix the main agent dimethylsiloxane and the cross-linking agent, spin-coat them into an encapsulation layer, place them above the pressure sensitive layer, and cover the ion gel.

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