Self-powered tactile sensor based on ion diode array and tactile detection method

Abstract

The invention provides a self-powered tactile sensor based on an ion diode array and a tactile detection method. The self-powered tactile sensor and the tactile detection method are used for solving the technical problem that an existing tactile sensor is insufficient in tactile perception when applied to an underwater environment. Comprising a porous substrate layer and a porous supporting layer, N ion diode units are arranged between the porous substrate layer and the porous supporting layer, the N ion diode units are arranged at intervals in the length direction of the porous substrate layer, and N is larger than or equal to 2; the ion diode unit comprises a p-type polyelectrolyte hydrogel layer, a porous separation membrane and an n-type polyelectrolyte hydrogel layer which are stacked, the p-type polyelectrolyte hydrogel layer contains fixed negative charges, and the n-type polyelectrolyte hydrogel layer contains fixed positive charges. The tactile sensor can realize self-powered tactile perception in an open electrolyte environment.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a self-powered tactile sensor and tactile detection method based on an ion diode array. Background Technology

[0002] Tactile sensing is a key technology in the fields of robotics and human-computer interaction. Existing tactile sensors are mainly based on piezoelectric, piezoresistive, or triboelectric mechanisms. These sensors have achieved good performance in air environments, but face many challenges when used in underwater environments: (1) complex waterproof packaging is required, which reduces the sensitivity and response speed of the sensor; (2) an external power supply system is required, which limits the autonomous operation capability of the sensor; (3) traditional piezoelectric / triboelectric sensors can only capture instantaneous pressure changes and cannot encode contact time information.

[0003] In recent years, ion migration-based sensing technology has attracted the attention of researchers. Porous polymer films in electrolyte solutions can generate electrical signals through differences in ion migration rates, enabling self-powered pressure sensing. However, existing ion sensors have the following shortcomings: (1) the signal duration is short (about 0.6 seconds), which cannot effectively encode time-based tactile information; (2) they lack ion rectification characteristics, and the signal features are not obvious enough; (3) it is difficult to realize position sensing and time encoding functions simultaneously.

[0004] An ion diode is an ion-electronic device composed of polyelectrolyte layers with opposite fixed charges, exhibiting ion rectification characteristics. Existing research shows that ion diodes can convert mechanical stimuli into electrical signals with a characteristic time constant of approximately 50 seconds. However, current studies have shown that ion diodes operate in dry or sealed environments, making them unsuitable for tactile sensing in open electrolyte environments. Summary of the Invention

[0005] The purpose of this invention is to provide a self-powered tactile sensor based on an ion diode array and a tactile detection method. This addresses the technical problem of insufficient tactile sensing in existing tactile sensors used in underwater environments.

[0006] First, this application provides a self-powered tactile sensor based on an ion diode array, comprising a porous substrate layer and a porous support layer, wherein N ion diode units are disposed between the porous substrate layer and the porous support layer, and the N ion diode units are spaced apart along the length direction of the porous substrate layer, wherein: N≥2;

[0007] The ion diode unit includes a p-type polyelectrolyte hydrogel layer, a porous separator membrane, and an n-type polyelectrolyte hydrogel layer stacked together. The p-type polyelectrolyte hydrogel layer contains a fixed negative charge, and the n-type polyelectrolyte hydrogel layer contains a fixed positive charge.

[0008] Optionally, electrodes for outputting signals are connected to both sides of the ion diode unit;

[0009] The electrode is a carbon nanotube electrode prepared by drop coating, and the sheet resistance of the carbon nanotube electrode is less than 1 kΩ / sq.

[0010] Optionally, both the porous substrate layer and the porous support layer are porous thermoplastic polyurethane layers, with a pore size of 150 nanometers to 15 micrometers and a porosity of 30-55%.

[0011] Optionally, the p-type polyelectrolyte hydrogel layer is a sodium polystyrene sulfonate-agarose composite hydrogel layer, and the n-type polyelectrolyte hydrogel layer is a polydiallyldimethylammonium chloride-agarose composite hydrogel layer.

[0012] Optionally, the porous separator is a porous membrane made of polytetrafluoroethylene, and the pore size of the porous separator is 0.45-1.2 micrometers.

[0013] Optionally, the number of ion diode units is 2-10, and the spacing between adjacent ion diode units is 5-20 mm.

[0014] Secondly, this application provides a tactile detection method, which uses the aforementioned self-powered tactile sensor based on an ion diode array, and the specific steps are as follows:

[0015] S1: Place the sensor in an electrolyte solution environment and simultaneously detect the current response of N ion diode units;

[0016] S2: Compare the current response values ​​of N ion diode units;

[0017] S3: The location of the ion diode cell with the largest current response value is used as the tactile application point.

[0018] Secondly, this application provides a method for manufacturing a tactile sensor, used to manufacture the aforementioned self-powered tactile sensor based on an ion diode array, the specific steps of which are as follows:

[0019] S1: Fabricate a porous substrate layer, a porous support layer, and an ion diode unit, and attach electrodes to both sides of the ion diode unit;

[0020] S2: Several ion diode units are spaced apart on a porous substrate, and copper wires are connected to each electrode using conductive silver paste.

[0021] S3: Cover N ion diode units with a porous support layer and seal the edges with polydimethylsiloxane.

[0022] Optionally, the specific steps for preparing the porous substrate layer and porous support layer in step S1 are as follows:

[0023] S1.1.1: Thermoplastic polyurethane particles are stirred and dissolved in N-dimethylformamide at 60°C for 6 hours, and polyethylene glycol is added and stirring is continued for 1 hour to obtain a casting solution;

[0024] S1.1.2: Pour the casting solution into a glass mold and dry it at 60°C for 24-36 hours. Immerse the dried film layer in anhydrous ethanol for 72 hours to leach out the polyethylene glycol. Replace the anhydrous ethanol solvent every 12 hours during the immersion process.

[0025] S1.2.3: Dry the film layer again at 60°C for 12 hours and cut it to the preset size to obtain a porous substrate layer and a porous support layer.

[0026] Optionally, the specific steps for fabricating the ion diode unit in step S1 are as follows:

[0027] S1.2.1: Dissolve agarose in deionized water at 90°C with stirring. After cooling to 60-65°C, add sodium polystyrene sulfonate solution and carbon nanotube dispersion. Mix thoroughly and pour into a mold. After standing at room temperature, obtain a p-type polyelectrolyte hydrogel layer.

[0028] S1.2.2: Dissolve agarose in deionized water at 90°C with stirring. After cooling to 60-65°C, add polydiallyldimethylammonium chloride solution and carbon nanotube dispersion. Mix thoroughly and pour into a mold. After standing at room temperature, obtain n-type polyelectrolyte hydrogel layer.

[0029] S1.2.3: The p-type polyelectrolyte hydrogel layer, the porous separator membrane, and the n-type polyelectrolyte hydrogel layer are stacked sequentially from bottom to top to obtain an ion diode unit.

[0030] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0031] 1. The tactile sensor of this application can realize self-powered tactile sensing in an open electrolyte environment, without complex packaging or external power supply, and generates electrical signals directly through mechanical stimulation.

[0032] 2. This application extends the signal duration by utilizing the rectification characteristics of ion diodes to achieve time information encoding.

[0033] 3. This application uses N ion diode units arranged in a bar array to detect the location of electric shock, and the tactile sensor uses conventional materials and processes, making it easy to manufacture and integrate.

[0034] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0035] The accompanying drawings of this invention are described below.

[0036] Figure 1 This is a schematic diagram of the porous substrate layer and ion diode unit of the present invention.

[0037] Figure 2 This is a cross-sectional view of the self-powered tactile sensor of the present invention.

[0038] Figure 3 This is a flowchart of the tactile detection method of the present invention.

[0039] Figure 4 This is a flowchart of the manufacturing method of the self-powered tactile sensor of the present invention.

[0040] Figure 5 This is a schematic diagram illustrating the rectification operation of the ion diode unit of the present invention.

[0041] Figure 6 This is a waveform diagram illustrating the time encoding principle of the ion diode unit in this invention.

[0042] Figure 7 This is a schematic diagram illustrating the principle of the self-powered tactile sensor for position sensing according to the present invention.

[0043] In the figure: 1-porous substrate layer; 2-ion diode unit; 201-p-type polyelectrolyte hydrogel layer; 202-porous separator membrane; 203-n-type polyelectrolyte hydrogel layer; 3-porous support layer; 4-electrode. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] Example 1:

[0046] like Figure 1 and Figure 2 The self-powered tactile sensor based on an ion diode array shown includes a porous substrate layer 1 and a porous support layer 3. N ion diode units 2 are disposed between the porous substrate layer 1 and the porous support layer 3. The N ion diode units 2 are spaced apart along the length direction of the porous substrate layer 1, wherein: N≥2.

[0047] The ion diode unit 2 includes a p-type polyelectrolyte hydrogel layer 201, a porous separator membrane 202, and an n-type polyelectrolyte hydrogel layer 203 stacked together. The p-type polyelectrolyte hydrogel layer 201 contains a fixed negative charge, and the n-type polyelectrolyte hydrogel layer 203 contains a fixed positive charge. Electrodes 4 for outputting signals are connected to both sides of the ion diode unit 2.

[0048] As one embodiment of this application, both the porous substrate layer 1 and the porous support layer 3 are porous thermoplastic polyurethane layers. The pore size of the porous substrate layer 1 and the porous support layer 3 is 150 nanometers to 15 micrometers, and the porosity is 30-55%. The porous structure allows the electrolyte solution to permeate freely while providing mechanical support. Figure 1 As shown, the self-powered tactile sensor has a long strip structure.

[0049] As one embodiment of this application, the p-type polyelectrolyte hydrogel layer 201 is a sodium polystyrene sulfonate-agarose composite hydrogel layer with a thickness of 0.5-2 mm and containing a fixed negative charge (PSS). - (group), selectively conducts cations (Na) in the electrolyte. + The n-type polyelectrolyte hydrogel layer 203 is a polydiallyldimethylammonium chloride-agarose composite hydrogel layer with a thickness of 0.5-2 mm, containing a fixed positive charge (PDA). + (group), selectively conducts anions (Cl) in the electrolyte. - The porous separator 202 is a porous membrane made of polytetrafluoroethylene. The pore size of the porous separator 202 is 0.45-1.2 micrometers. It is used to separate the p-type polyelectrolyte hydrogel layer 201 and the n-type polyelectrolyte hydrogel layer 203, while allowing ions to pass through.

[0050] In one embodiment of this application, the electrode 4 is a carbon nanotube electrode prepared by drop coating, and the sheet resistance of the carbon nanotube electrode is less than 1 kΩ / sq. The number of ion diode units 2 is 2-10, and the spacing between adjacent ion diode units 2 is 5-20 mm. Each ion diode unit 2 can output a signal independently, and the contact point (press point) position is sensed by comparing the signal strength of each unit.

[0051] In one embodiment of this application, the number of ion diode units 2 is four. The overall size of the tactile sensor is 60mm × 15mm × 3mm, and the size of the ion diode unit 2 is 10mm × 15mm × 2mm. The spacing between adjacent ion diode units 2 is 12mm (center to center). In practical use, the number and spacing of the ion diode units 2 can be adjusted according to application requirements: for example, a dual-unit sensor with a base size of 30mm × 15mm is suitable for simple orientation detection; a six-unit sensor with a base size of 90mm × 15mm is suitable for higher precision position detection; and a ten-unit sensor with a base size of 150mm × 15mm is suitable for large-area tactile sensing.

[0052] In this embodiment, the ion rectification principle is as follows: in the p-type polyelectrolyte hydrogel layer 201, the negatively charged PSS - The groups are covalently attached to the polymer backbone. According to the Donnan repulsion principle, the fixed negatively charged Na+ molecules move through electrostatic attraction. + Cations, while repelling Cl - The presence of anions allows the layer to selectively permeate to cations. Conversely, the n-type polyelectrolyte hydrogel layer 203 contains fixed PDA. + Positive charge is beneficial to Cl - Transport and repel Na + This asymmetric ion selectivity promotes the forward migration of ions from the p-type polyelectrolyte hydrogel layer 201 to the n-type polyelectrolyte hydrogel layer 203, while hindering the reverse migration, resulting in a rectifying effect. For example... Figure 5 As shown, Na + / Cl - Selective migration between the p-type polyelectrolyte hydrogel layer 201, the porous separator membrane 202, and the n-type polyelectrolyte hydrogel layer 203 creates an ion rectification effect.

[0053] The pressure response principle is as follows: When external pressure is applied to the tactile sensor, the ion diode unit 2 is compressed and deformed, driving ions in the electrolyte solution to migrate through the ion diode unit 2. Due to the ion rectification characteristics, the forward ion flow is promoted, generating a directional current output. The greater the pressure, the greater the ion migration and the stronger the output current.

[0054] The time encoding principle is as follows: Due to the kinetic characteristics of ion diffusion in hydrogel layers 201 and 203, the current signal exhibits a characteristic time profile: the rise time constant (τ_rise) is 3-10 seconds, and the decay time constant (τ_decay) is 30-60 seconds. These time constants are independent of the contact duration, while the plateau width of the signal directly reflects the duration of pressure, thus achieving the encoding of time information. Figure 6As shown, the duration of tactile sensation is encoded using time parameters such as τ_{rise}, t_{hold}, and τ_{decay}.

[0055] Example 2:

[0056] like Figure 3 The tactile detection method shown is characterized by employing the self-powered tactile sensor based on an ion diode array as described in Example 1, and the specific steps are as follows:

[0057] S1: Place the sensor in an electrolyte solution environment and simultaneously detect the current response of N ion diode units 2;

[0058] S2: Compare the current response values ​​of N ion diode units 2;

[0059] S3: The position of the ion diode unit 2 with the largest current response value is taken as the tactile application point.

[0060] In this embodiment, when pressure is applied to a certain position of the tactile sensor, the ion diode unit 2 near the pressure point generates a larger current response, while the ion diode unit 2 further away from the pressure point generates a weaker response. By comparing the ratio of the current intensities of each unit, the position of the touch point (press point) can be calculated, achieving one-dimensional position sensing. This ratio method eliminates the dependence on the absolute pressure magnitude, making position detection effective over a wide pressure range. Figure 7 As shown, Figure 7 Channels 1, 2, 3 and 4 are four ion diode units 2, and one-dimensional position determination is achieved by comparing the distribution of output intensity of each channel.

[0061] Example 3:

[0062] like Figure 4 The method for manufacturing a tactile sensor, as shown in Example 1, is a self-powered tactile sensor based on an ion diode array. The specific steps are as follows:

[0063] S1: Fabricate a porous substrate layer 1, a porous support layer 3, and an ion diode unit 2, and attach electrodes 4 to both sides of the ion diode unit 2; the specific steps are as follows:

[0064] S1.1: Preparation of porous substrate layer 1 and porous support layer 3:

[0065] S1.1.1: Dissolve 1g of thermoplastic polyurethane particles in 5mL of N-dimethylformamide at 60°C for 6 hours, and add polyethylene glycol (0.2mL of PEG400 and 0.2mL of PEG600) as a pore-forming agent, and continue stirring for 1 hour to obtain a casting solution;

[0066] S1.1.2: Pour the casting solution into a glass mold and dry it at 60°C for 24-36 hours. Immerse the dried film layer in anhydrous ethanol for 72 hours to leach out the polyethylene glycol. Replace the anhydrous ethanol solvent every 12 hours during the immersion process.

[0067] S1.2.3: Dry the film layer again at 60°C for 12 hours and cut it to the preset size (60 mm × 15 mm) to obtain the porous substrate layer 1 and the porous support layer 3.

[0068] S1.2: Fabrication of Ion Diode Unit 2:

[0069] S1.2.1: Dissolve agarose in deionized water at 90°C with stirring. After cooling to 60-65°C, add 2.8 mL of sodium polystyrene sulfonate solution (25 wt%) and 0.5 mL of carbon nanotube dispersion. Mix thoroughly and pour into a mold. After standing at room temperature for 30 min, obtain p-type polyelectrolyte hydrogel layer 201.

[0070] S1.2.2: Dissolve 0.3 g agarose in 7.2 mL of deionized water at 90°C with stirring. After cooling to 60-65°C, add 2.5 mL of polydiallyldimethylammonium chloride solution (25 wt%) and 0.5 mL of carbon nanotube dispersion. After thorough mixing, pour into a mold and let stand at room temperature for 30 min to obtain n-type polyelectrolyte hydrogel layer 203.

[0071] S1.2.3: The p-type polyelectrolyte hydrogel layer 201, the porous separator membrane 202 and the n-type polyelectrolyte hydrogel layer 203 are stacked sequentially from bottom to top to obtain the ion diode unit 2.

[0072] In this embodiment, the porous separator membrane 202 is pre-wetted by soaking in a 0.5M NaCl solution for 30 minutes.

[0073] S2: Several ion diode units 2 are spaced on the porous substrate layer 1, and copper wires are connected to each electrode 4 using conductive silver paste.

[0074] S3: Cover the N ion diode units 2 with a porous support layer 3 and seal the edges with polydimethylsiloxane.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A self-powered tactile sensor based on an ion diode array, characterized in that, It includes a porous substrate layer (1) and a porous support layer (3), and N ion diode units (2) are disposed between the porous substrate layer (1) and the porous support layer (3). The N ion diode units (2) are spaced apart along the length direction of the porous substrate layer (1), wherein: N≥2; The ion diode unit (2) includes a p-type polyelectrolyte hydrogel layer (201), a porous separator membrane (202), and an n-type polyelectrolyte hydrogel layer (203) stacked together. The p-type polyelectrolyte hydrogel layer (201) contains a fixed negative charge, and the n-type polyelectrolyte hydrogel layer (203) contains a fixed positive charge.

2. The self-powered tactile sensor based on an ion diode array according to claim 1, characterized in that, Both sides of the ion diode unit (2) are connected to electrodes (4) for outputting signals. The electrode (4) is a carbon nanotube electrode prepared by drop coating, and the sheet resistance of the carbon nanotube electrode is less than 1 kΩ / sq.

3. The self-powered tactile sensor based on an ion diode array according to claim 1, characterized in that, The porous substrate layer (1) and the porous support layer (3) are both porous thermoplastic polyurethane layers. The pore size of the porous substrate layer (1) and the porous support layer (3) is 150 nanometers to 15 micrometers, and the porosity is 30-55%.

4. A self-powered tactile sensor based on an ion diode array according to claim 1, characterized in that, The p-type polyelectrolyte hydrogel layer (201) is a sodium polystyrene sulfonate-agarose composite hydrogel layer, and the n-type polyelectrolyte hydrogel layer (203) is a polydiallyldimethylammonium chloride-agarose composite hydrogel layer.

5. A self-powered tactile sensor based on an ion diode array according to claim 1, characterized in that, The porous separator (202) is a porous membrane made of polytetrafluoroethylene, and the pore size of the porous separator (202) is 0.45-1.2 micrometers.

6. A self-powered tactile sensor based on an ion diode array according to claim 1, characterized in that, The number of ion diode units (2) is 2-10, and the spacing between adjacent ion diode units (2) is 5-20 mm.

7. A tactile detection method, characterized in that, The self-powered tactile sensor based on an ion diode array as described in any one of claims 1-6 comprises the following steps: S1: Place the sensor in an electrolyte solution environment and simultaneously detect the current response of N ion diode units (2); S2: Compare the current response values ​​of N ion diode units (2); S3: The position of the ion diode unit (2) with the largest current response value is taken as the tactile application point.

8. A method for manufacturing a tactile sensor, characterized in that, The specific steps for manufacturing the self-powered tactile sensor based on an ion diode array as described in any one of claims 1-6 are as follows: S1: Prepare a porous substrate layer (1), a porous support layer (3) and an ion diode unit (2), and attach electrodes (4) to both sides of the ion diode unit (2). S2: Several ion diode units (2) are spaced apart on the porous substrate (1), and copper wires are connected to each electrode (4) using conductive silver paste. S3: Cover the N ion diode units (2) with a porous support layer (3) and seal the edges with polydimethylsiloxane.

9. A method for manufacturing a tactile sensor according to claim 8, characterized in that, The specific steps for preparing the porous substrate layer (1) and the porous support layer (3) in step S1 are as follows: S1.1.1: Thermoplastic polyurethane particles are stirred and dissolved in N-dimethylformamide at 60°C for 6 hours, and polyethylene glycol is added and stirring is continued for 1 hour to obtain a casting solution; S1.1.2: Pour the casting solution into a glass mold and dry it at 60°C for 24-36 hours. Immerse the dried film layer in anhydrous ethanol for 72 hours to leach out the polyethylene glycol. Replace the anhydrous ethanol solvent every 12 hours during the immersion process. S1.2.3: Dry the film layer again at 60°C for 12 hours and cut it according to the preset size to obtain a porous substrate layer (1) and a porous support layer (3).

10. A method for manufacturing a tactile sensor according to claim 8, characterized in that, The specific steps for fabricating the ion diode unit (2) in step S1 are as follows: S1.2.1: Dissolve agarose in deionized water at 90°C with stirring. After cooling to 60-65°C, add sodium polystyrene sulfonate solution and carbon nanotube dispersion. After mixing thoroughly, pour into a mold and let stand at room temperature to obtain p-type polyelectrolyte hydrogel layer (201). S1.2.2: Dissolve agarose in deionized water at 90°C with stirring. After cooling to 60-65°C, add polydiallyldimethylammonium chloride solution and carbon nanotube dispersion. After thorough mixing, pour into a mold and let stand at room temperature to obtain n-type polyelectrolyte hydrogel layer (203). S1.2.3: The p-type polyelectrolyte hydrogel layer (201), the porous separator membrane (202) and the n-type polyelectrolyte hydrogel layer (203) are stacked sequentially from bottom to top to obtain the ion diode unit (2).

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