Temperature-pressure tactile sensor based on self-permeation assembly and preparation method of temperature-pressure tactile sensor

Abstract

The invention provides a temperature-pressure tactile sensor based on self-permeation assembly and a preparation method thereof. A multi-layer composite PON film of the tactile sensor comprises a P-type sensing layer, an N-type sensing layer, a middle insulating layer and an outermost packaging layer; the middle insulating layer is arranged between the P-type sensing layer and the N-type sensing layer; the outermost packaging layer covers the outer side surfaces of the P-type sensing layer and the N-type sensing layer and is packaged by the sensing layer; a substrate material of the P-type sensing layer is water-based polyurethane (WPU), and an active material in the P-type sensing layer is single-walled carbon nanotubes (SWCNTs); a substrate material of the N-type sensing layer is water-based polyurethane (WPU), and an active material in the N-type sensing layer is a polyethyleneimine (PEI) modified single-walled carbon nanotube; the middle insulating layer adopts waterborne polyurethane without a conductive material as a substrate; the outermost packaging layer is a polyimide film; according to the scheme provided by the invention, physical stimulation and loss in a signal transmission process can be reduced, a temperature sensing signal is improved, and meanwhile, external pressure information is decoupled.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature-pressure tactile sensors based on self-infiltration assembly, and in particular relates to a temperature-pressure tactile sensor based on self-infiltration assembly and a preparation method thereof. Background Art

[0002] Tactile sensors are used to give intelligent robots bionic functions by imitating human skin perception, promoting future technological advances such as human-computer interaction, intelligent robots, and VR real-scene control. It requires the integration and decoupling of multi-dimensional stimuli such as temperature and pressure in a compact single device during design, and also requires extremely high sensing indicators, including sensitivity and detection limit. Current research on tactile sensors focuses on improving pressure perception capabilities, and by optimizing key indicators such as the linear range and sensitivity of pressure sensors, it is possible to accurately identify the softness of objects and assist in efficient grasping operations. However, from a bionics perspective, the integration of temperature and pressure sensing functions is essential to ensure the stability and adaptability of the system in actual interactions. Therefore, improving indicators such as the sensitivity of temperature sensing technology to accurately identify small temperature differences and formulating excellent hierarchical strategies to achieve joint recognition effects have become important issues in the current development of tactile sensors.

[0003] Tactile temperature sensors based on the thermoelectric (TE) effect can autonomously detect temperature-induced voltage signals without the need for an external power supply. Conductive polymers, inorganic metal materials, π-π conjugated materials and other thermoelectric materials are often used as sensitive materials for sensing electrodes, significantly improving temperature perception (Nano Energy 2022, 98, 107273; Nat. Commun. 2022, 13 (1), 5224); However, the sensitivity that can be achieved by simple composite materials is limited, so spiral, wavy, and multi-layer junction flexible temperature sensors have been developed, and for more flexible applications and higher sensitivity (Nat. Commun. 2024, 15, 2521; Adv. Mater. 36, 2310613), referring to the series boosting mechanism of inorganic thermoelectric legs, pn-type TE materials are assembled to achieve a boosting effect, which greatly improves the thermal pressure signal output by temperature stimulation. However, due to the limited number of p-layers and n-layers in series, improving the strength of the output voltage signal is still a problem to be solved. Therefore, the main problems faced in the current integrated flexible tactile sensing include:

[0004] (1) Tactile sensing cannot establish a hierarchical signal transmission channel and simultaneously analyze external pressure and temperature information to reconstruct the three-dimensional morphology of the environment;

[0005] (2) Tactile sensing cannot achieve high-sensitivity temperature sensing capabilities to accurately identify tiny temperature differences.

[0006] Based on the technical problems existing in the above-mentioned tactile sensing, there is no relevant solution yet; therefore, there is an urgent need to find effective solutions to solve the above-mentioned problems. Summary of the invention

[0007] The purpose of the present invention is to address the deficiencies in the above-mentioned technologies and propose a temperature-pressure tactile sensor based on self-infiltration assembly and a preparation method, aiming to solve the problem that existing tactile sensors can simultaneously analyze external pressure and temperature information.

[0008] The invention provides a temperature-pressure tactile sensor based on self-infiltration assembly, wherein the tactile sensor comprises a multi-layer composite PON film; the multi-layer composite PON film comprises a P-type sensing layer, an N-type sensing layer, an intermediate insulating layer and an outermost encapsulation layer; the intermediate insulating layer is arranged between the P-type sensing layer and the N-type sensing layer; the outermost encapsulation layer covers the outer side surfaces of the P-type sensing layer and the N-type sensing layer to encapsulate the P-type sensing layer and the N-type sensing layer; the base material of the P-type sensing layer is water-based polyurethane WPU, and the active material in the P-type sensing layer is single-walled carbon nanotubes SWCNTs; the base material of the N-type sensing layer is water-based polyurethane WPU, and the active material in the N-type sensing layer is single-walled carbon nanotubes modified by polyethyleneimine PEI; the intermediate insulating layer adopts water-based polyurethane without conductive material as a base; and the outermost encapsulation layer is a polyimide film.

[0009] Furthermore, the mass ratio of the base materials CNF and water-based polyurethane WPU of the P-type sensing layer and the N-type sensing layer is 1:10.

[0010] Furthermore, the single-walled carbon nanotubes SWCNTs account for 5 wt.% of the total solid content of the P-type sensing layer.

[0011] Furthermore, the mass ratio of single-walled carbon nanotubes SWCNTs to polyethyleneimine PEI in the N-type sensing layer is 1:5.

[0012] Furthermore, during the preparation process of the multi-layer composite PON film, pores perpendicular to the film plane are formed by the affinity of the uniform matrix between the layers of the film and the bubbles generated in the bottom aqueous polyurethane.

[0013] Furthermore, a conductive path is formed between the P-type sensing layer and the N-type sensing layer by the slurry penetrating into the middle layer.

[0014] Furthermore, the temperature sensing sensitivity of the multilayer composite PON film is 1203 μV K -1 , the minimum detection limit of the multilayer composite PON film is 0.001K.

[0015] Furthermore, the detection range of the pressure sensor of the multi-layer composite PON film is 0-620 kPa.

[0016] Furthermore, the circuit wiring directions of the PON composite film assembled into the PON touch sensor are on the left and right sides of the upper and lower sides of the film plane.

[0017] Accordingly, in combination with the above scheme, the present invention also provides a method for preparing a temperature-pressure tactile sensor based on self-infiltration assembly, the preparation method comprising the following steps:

[0018] S1: After mixing oxidized cellulose nanofibers CNF and aqueous polyurethane solution WPU, ultrasonic crushing is performed to obtain a defoamed uniform O-type slurry;

[0019] S2: injecting the O-type slurry into the mold and curing it to obtain a non-conductive intermediate insulating layer film;

[0020] S3: Then, the single-walled carbon nanotubes SWCNTs are dispersed with dimethyl sulfoxide DMSO, CNF, and waterborne polyurethane WPU by stirring, and then a uniform P-type slurry is obtained after ultrasonic treatment;

[0021] S4: Similarly, adding polyethyleneimine in different mass proportions as a nitrogen-containing dopant to the P-type slurry obtained in the above step S3, and obtaining a doped N-type slurry after ultrasonic treatment;

[0022] S5: injecting and laying P-type slurry on the upper layer of the film obtained in the above step S2, and drying after sufficient penetration to obtain a PO film;

[0023] S6: Similarly, inject and spread N-type slurry on the lower layer of PO film, fully penetrate and dry to obtain PON composite film;

[0024] S7: A polyimide film with a thickness of 25 microns is adhered to both sides of the PON composite film obtained in the above step S6 to form a tactile sensor;

[0025] S8: The tactile sensor obtained in the above step S7 is bonded to a copper wire with conductive silver paste, and the other end is connected to a data recorder to record the sensing signal obtained by temperature-pressure stimulation.

[0026] Furthermore, in step S1: 5.5 mg / ml of TEMPO-mediated oxidized cellulose nanofibers CNF and 30 wt.% of WPU were stirred and mixed, and then ultrasonically crushed for 30 minutes to obtain a defoamed uniform O-type slurry.

[0027] Further, in step S2: the obtained O-type slurry is injected into a container having an internal volume of 20*10*3mm 3 The non-conductive middle insulating layer film was obtained after being placed in a silicone mold and cured at 60 degrees Celsius for 12 hours.

[0028] Further, in step S3: 13.75 mg of ultrapure SWCNTs and dimethyl sulfoxide, the CNF solution was stirred and evenly dispersed in ultrapure water, and a SWCNTs mixed slurry was obtained after ultrasonic crushing, and then 0.883 ml of WPU was added, stirred evenly to fully wrap the SWCNTs dispersed in the slurry, and then ultrasonicated again for 30 minutes to obtain a P-type slurry.

[0029] Furthermore, in step S4: Similarly, different mass proportions of polyethyleneimine are added as nitrogen-containing dopants to the SWCNTs mixed slurry obtained in S3 above, and WPU aqueous solution is added, stirred evenly, and ultrasonicated for 30 minutes to obtain a doped N-type slurry.

[0030] Furthermore, in step S5: the P-type slurry is injected and spread on the upper layer of the film obtained in the above S2, and after full penetration for 5 minutes, it is placed in an oven at 60 degrees Celsius for drying for 12 hours to obtain a PO film.

[0031] Furthermore, in step S6: similarly, N-type slurry is injected and spread on the lower layer of the PO film, fully infiltrated for 5 minutes and then dried for 12 hours to obtain a PON composite film.

[0032] The solution provided by the present invention forms a dense vertical layered structure through layered polymerization through the joint action of water-based polyurethane and CNF. The compressible nanolayer can not only make PON respond quickly to pressure stimulation, but also, compared with other special-shaped materials, when the i-TE material is applied to temperature sensing, PON can output a high thermoelectric voltage value under the same temperature difference; at the same time, the same matrix is ​​used in different layers, and the affinity of the uniform matrix is ​​used to effectively eliminate the interface resistance and contact thermal resistance between layers, reduce the loss in the physical stimulation and signal transmission process, and can simultaneously analyze the external pressure and temperature information. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] The present invention will be further described below in conjunction with the accompanying drawings:

[0035] Figure 1 A schematic diagram of the structure of a temperature-pressure tactile sensor based on self-infiltration assembly provided by an embodiment of the present invention;

[0036] Figure 2 is a flow chart for preparing the film of the present invention;

[0037] Figure 3 It is a schematic diagram of the sensitivity of different SWCNTs mass fractions of the present invention;

[0038] Figure 4Schematic diagram of sensitivity and conductivity of N-type films with different PEI ratios of the present invention;

[0039] Figure 5 1 is a valence bond analysis (C 1s / O 1s / N 1s) diagram of N-type films with different PEI ratios of the present invention;

[0040] Figure 6 It is a schematic diagram of the PAN and PON assembly structure of the present invention;

[0041] Figure 7 This is a schematic diagram of the contact angle test of the present invention;

[0042] Figure 8 It is a sensitivity diagram of PAN and PON of the present invention;

[0043] Fig. 9 (a) Schematic diagram of the decoupling device and (b) decoupling performance diagram of the temperature and pressure of the PON tactile sensor of the present invention;

[0044] Fig.10 This is a pressure sensing performance diagram of the PON tactile sensor of the present invention;

[0045] Fig.11 This is a schematic diagram of the PON of the present invention being worn on a robotic arm as a smart fingertip;

[0046] Fig.12 Schematic diagram of the hierarchical strategy of the smart finger sleeve of the present invention;

[0047] Fig.13 (a) Schematic diagram of the smart finger cuff of the present invention, (b) (c) temperature and (d) pressure sensing signal schematic diagrams.

[0048] In the attached summary figure: 1. Outermost packaging layer; 2. P-type sensitive layer; 3. Middle penetration layer; 4. N-type sensitive layer. DETAILED DESCRIPTION

[0049] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0052] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "front", "back", "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] like Figure 1As shown, the present invention provides a temperature-pressure tactile sensor based on self-infiltration assembly, which includes a multi-layer composite PON film. Specifically, the multi-layer composite PON film includes a P-type sensing layer 2 (i.e., a P-type film), an N-type sensing layer 4 (i.e., an N-type film), an intermediate insulating layer 3, and an outermost encapsulation layer 1; wherein the intermediate insulating layer 3 is arranged between the P-type sensing layer 2 and the N-type sensing layer 4; the outermost encapsulation layer 1 covers the outer side surfaces of the P-type sensing layer 2 and the N-type sensing layer 4 to encapsulate the P-type sensing layer 2 and the N-type sensing layer 4; the base material of the P-type sensing layer 2 is water-based polyurethane WPU, and the active material in the P-type sensing layer 2 is single-walled carbon nanotubes SWCNTs; the base material of the N-type sensing layer 4 is water-based polyurethane WPU, and the active material in the N-type sensing layer 4 is polyethyleneimine PEI modified single-walled carbon nanotubes; the middle insulating layer 3 uses water-based polyurethane without conductive material as the substrate; the outermost encapsulation layer 1 is a polyimide film; the temperature-pressure tactile sensor based on self-infiltration assembly provided by the present invention forms a dense vertical layered structure through the joint action of water-based polyurethane and CNF, and the compressible nanolayer can not only make PON respond quickly to pressure stimulation, but also compared with other special-shaped materials, the i-TE material is used in temperature sensing, so that PON can output high thermoelectric voltage value under the same temperature difference; at the same time, the same matrix is ​​used in different layers, and the affinity of the uniform matrix is ​​used to effectively eliminate the interface resistance and contact thermal resistance between layers, reduce the loss of physical stimulation and signal transmission process, and can simultaneously analyze external pressure and temperature information. A temperature-pressure tactile sensor based on self-infiltration assembly provided by the present invention can reduce the loss of physical stimulation and signal transmission process, greatly improve the temperature sensing signal, and can simultaneously decouple external pressure information.

[0055] Preferably, in combination with the above scheme, the waterborne polyurethane selected for preparing the multi-layer composite PON film is an anionic aliphatic waterborne polyurethane.

[0056] Preferably, in combination with the above scheme, the mass ratio of the base material CNF and the water-based polyurethane WPU of the P-type sensing layer and the N-type sensing layer is 1:10; specifically, by adjusting the optimal ratio of the solid content of SWCNTs in the P-type slurry, the carrier content in the system is optimized, thereby achieving the decoupling of the two key indicators of sensitivity and conductivity; the proportion of the N-type dopant PEI is adjusted to obtain the saturated doping ratio of the SWCNTs modified sites, and then the penetration of the P / N-type slurry in the middle layer is utilized to enable the P-type and N-type to form a connected circuit without the need for external electrodes or conductive slurry.

[0057] Preferably, in combination with the above solution, the single-walled carbon nanotubes SWCNTs account for 5 wt.% of the total solid content of the P-type sensing layer (ie, a single-layer P-type thin film).

[0058] Preferably, in combination with the above scheme, the mass ratio of single-walled carbon nanotubes SWCNTs to polyethyleneimine PEI in the N-type sensing layer is 1:5; specifically, by adjusting the optimal ratio of the solid content of SWCNTs in the P-type slurry, the carrier content in the system is optimized, thereby achieving decoupling of the two key indicators of sensitivity and conductivity; the proportion of the N-type dopant PEI is adjusted to obtain the saturated doping ratio of the SWCNTs modified sites, and then the penetration of the P / N-type slurry in the middle layer is utilized to enable the P-type and N-type to form a connected circuit without the need for external electrodes or conductive slurry.

[0059] By adopting the above scheme, when the sensor is stimulated by temperature and pressure at the same time, due to the different sensing mechanisms, the change values ​​of the output temperature-voltage and pressure-resistance are independent and stable, ensuring that there is no crosstalk from other parameters; specifically, the sensing mechanisms are different. On the one hand, temperature stimulation tends to cause carriers to move to form a stable voltage difference, and on the other hand, when pressure is loaded, the thin film lamellar structure undergoes reversible deformation, causing the resistance to change. Therefore, the change values ​​of the output temperature-voltage and pressure-resistance are independent and stable, and the temperature and pressure show good decoupling.

[0060] Preferably, in combination with the above scheme, the multi-layer composite PON film of the tactile sensor forms pores perpendicular to the plane of the film through the affinity of the uniform matrix between the layers of the film and the bubbles generated in the bottom aqueous polyurethane during the preparation process. This is beneficial to the penetration of the sensing materials on both sides into the middle layer, and the time for full penetration obtained by the contact angle test is 400 seconds.

[0061] Preferably, in combination with the above solution, there is no need to connect the thin films of the P-type sensing layer and the N-type sensing layer in series with wires, but a conductive path is formed between the P-type sensing layer and the N-type sensing layer by the penetration of slurry in the middle layer.

[0062] Preferably, in combination with the above solution, the temperature sensing sensitivity of the multilayer composite PON film is 1203 μV K -1 , the minimum detection limit of the multilayer composite PON film is 0.001K.

[0063] Preferably, in combination with the above solution, the pressure sensing detection range of the multi-layer composite PON film is 0-620 kPa.

[0064] Preferably, in combination with the above solution, the circuit wiring direction of the PON composite film assembled into the PON tactile sensor is on the left and right sides of the upper and lower sides of the film plane, as specifically referred to in Figure 6 Wires are connected at the midpoints ② and ③; wherein the circuit wiring direction of comparative example 3 is on the same side of the upper and lower sides of the film plane, and wires are connected at specific reference points ① and ②.

[0065] Preferably, in combination with the above scheme, the size of the SWCNTs used in the preparation of the PON film is 1-2nm in outer diameter and 5-20μm in length. The thinner the diameter of the single-walled carbon nanotube SWCNTs and the longer the length, the better the conductivity. Due to the high length-diameter ratio of the single-walled carbon nanotube, it can form a three-dimensional conductive network at a very low addition amount.

[0066] The tactile sensor provided by the present invention also includes a copper electrode and a conductive silver paste.

[0067] Accordingly, in combination with the above scheme, the present invention also provides a method for preparing a temperature-pressure tactile sensor based on self-infiltration assembly, the preparation method comprising the following process:

[0068] S1: After the oxidized cellulose nanofibers CNF and the aqueous polyurethane solution WPU are stirred and mixed, ultrasonic crushing is performed to obtain a defoamed uniform O-type slurry; specifically, the mass ratio of the oxidized cellulose nanofibers CNF to the aqueous polyurethane solution WPU is 1:10;

[0069] S2: injecting the O-type slurry into the mold and curing it to obtain a non-conductive intermediate insulating layer film;

[0070] S3: Then, the single-walled carbon nanotubes SWCNTs are stirred and dispersed with dimethyl sulfoxide DMSO, CNF, and waterborne polyurethane WPU, and then a uniform P-type slurry is obtained after ultrasonic treatment; specifically, the optimal mass ratio of the active material SWCNTs to the tactile solid content of the sensor is 5wt.%, 10wt.%, and 15wt.%;

[0071] S4: Similarly, adding polyethyleneimine in different mass ratios as a nitrogen-containing dopant to the P-type slurry obtained in the above step S3, and obtaining a doped N-type slurry after ultrasonic treatment; specifically, the optimal mass ratio of SWCNTs to PEI is 1:0, 1:5, 1:10, and 1:15;

[0072] S5: injecting and laying P-type slurry on the upper layer of the film obtained in the above step S2, and drying after sufficient penetration to obtain a PO film; in this step, the penetration time is 400s according to the penetration angle test;

[0073] S6: Similarly, inject and spread N-type slurry on the lower layer of PO film, fully penetrate and dry to obtain PON composite film; in this step, the penetration time is 400s according to the penetration angle test;

[0074] The temperature sensing sensitivity of the PON tactile sensor prepared by the above steps is 1203.6 μV K -1The response time is 0.77s and the detection limit is 0.001K; the detection range of the pressure sensing function is 0-620kPa; when worn as a smart fingertip on a robotic hand, it innovatively proposes a bionic operation strategy of "temperature perception-precise positioning control-fine movement control-real-time pressure feedback-dynamic adjustment and optimization", enriching the functional dimensions of the fingertip tactile bionic sensor.

[0075] S7: A polyimide film with a thickness of 25 microns is adhered to both sides of the PON composite film obtained in the above step S6 to form a tactile sensor;

[0076] S8: The tactile sensor obtained in the above step S7 is bonded to a copper wire with conductive silver paste, and the other end is connected to a data recorder to record the sensing signal obtained by temperature-pressure stimulation.

[0077] Preferably, in combination with the above scheme, in step S1: 5.5 mg / ml of TEMPO-mediated oxidized cellulose nanofibers CNF and 30 wt.% of WPU are stirred and mixed, and then ultrasonically crushed for 30 minutes to obtain a defoamed uniform O-type slurry.

[0078] Preferably, in combination with the above scheme, in step S2: inject the obtained O-type slurry into a container with an internal volume of 20*10*3mm 3 The non-conductive middle insulating layer film was obtained after being placed in a silicone mold and cured at 60 degrees Celsius for 12 hours.

[0079] Preferably, in combination with the above scheme, in step S3: 13.75 mg of ultrapure SWCNTs and dimethyl sulfoxide, the CNF solution is stirred and evenly dispersed in ultrapure water, and SWCNTs mixed slurry is obtained after ultrasonic crushing, and then 0.883 ml of WPU is added, stirred evenly to fully wrap the SWCNTs dispersed in the slurry, and then ultrasonicated again for 30 minutes to obtain P-type slurry.

[0080] Preferably, in combination with the above scheme, in step S4: similarly, different mass proportions of polyethyleneimine are added as nitrogen-containing dopants to the SWCNTs mixed slurry obtained in S3 above, and WPU aqueous solution is added, stirred evenly, and ultrasonicated for 30 minutes to obtain a doped N-type slurry.

[0081] Preferably, in combination with the above scheme, in step S5: inject and spread P-type slurry on the upper layer of the film obtained in the above S2, fully penetrate for 5 minutes, and then put it into a 60 degree Celsius oven for drying for 12 hours to obtain a PO film.

[0082] Preferably, in combination with the above solution, in step S6: similarly, N-type slurry is injected and laid on the lower layer of the PO film, fully infiltrated for 5 minutes and then dried for 12 hours to obtain a PON composite film.

[0083] With this technical solution, waterborne polyurethane and CNF are polymerized to form a dense vertical layered structure. The compressible nanolayer not only makes PON respond quickly to pressure stimulation, but also outputs high thermal pressure values ​​under the same temperature difference when i-TE materials are used in temperature sensing compared with other special-shaped materials. At the same time, the affinity of the uniform matrix between each layer of film is used to effectively eliminate the interface resistance and contact thermal resistance between layers, reduce the loss of physical stimulation and signal transmission process, and facilitate the penetration of sensing materials on both sides in the middle layer. The P / N type slurry forms a penetration point in the middle layer, so that the P type and N type can form a connected series circuit without the need for external electrodes or conductive slurry. Among them, compared with PAN using adhesive material as the middle layer, the sensitivity of PON is increased by 5.0 times.

[0084] Specifically, the temperature-pressure decoupling signal device measured in the following embodiments refers to Fig. 9 shown.

[0085] Example 1: Preparation of a single-layer P-type thin film

[0086] like Figure 2 As shown, the preparation process of the single-layer P-type film is a thermal deposition method. Specifically, 13.25 mg of ultrapure single-walled carbon nanotubes, 4 ml of dimethyl sulfoxide, and 4.66 ml of TEMPO-mediated oxidized cellulose nanofibers CNF with a concentration of 5.5 mg / ml were dispersed in 25 ml of ultrapure water, and ultrasonic cell disruption was used to obtain a SWCNTs mixed slurry after 30 minutes of ultrasonication. 0.883 ml of 30 wt.% aqueous polyurethane was added to fully wrap the SWCNTs dispersed in the slurry. The P-type slurry obtained after further ultrasonication for 10 minutes was injected into a 3*3*0.5 cm 3 A P-type film is obtained by curing in a silicone mold at 60 degrees Celsius; the mass fraction of the sensitive material single-walled carbon nanotubes in the polymer matrix waterborne polyurethane is 5wt.%.

[0087] Comparative Example 1:

[0088] Based on Example 1, the present embodiment is different in that 6.63, 26.5, and 53 mg of SWCNTs are added in step S3, accounting for 2.5 wt.%, 10 wt.%, and 20 wt.% of the mass fraction of the aqueous polyurethane, respectively. 0.883 ml of 30 wt.% aqueous polyurethane is added to the obtained SWCNTs mixed slurry, and the P-2.5, P-10, and P-20 slurries obtained after further ultrasonication for 10 minutes are injected into 3*3*0.5 cm 3 The P-type films with different mass fractions of SWCNTs were obtained by curing at 60 degrees Celsius in a silicone mold.

[0089] The temperature sensing performance of the SWCNTs films of Example 1 and Comparative Example 1 obtained above with different mass fractions was tested. The results are as follows: Figure 3 As shown in Figure 1, when the content of SWCNTs is 2.5wt.%, the complete conductive network cannot be constructed due to the low dosage, so no effective hot pressure signal can be detected. In particular, in Example 1, the highest sensitivity value of 54.3μV K -1 This is because the appropriate carrier concentration reduces the scattering of carriers during transmission, achieving the decoupling of the two key indicators of sensitivity and conductivity.

[0090] Example 2: Preparation of a single-layer N-type thin film

[0091] Based on Example 1, the difference of this example is that in step S4, 1 ml of PEI is added as a nitrogen-containing dopant to the obtained SWCNTs mixed slurry, and 0.883 ml of 30 wt.% aqueous polyurethane is added, and the N-type slurry obtained after further ultrasonication for 10 minutes is injected into 3*3*0.5 cm 3 The N-type film was obtained by curing at 60 degrees Celsius in a silicone mold. The mass ratio of SWCNTs to PEI was 1:5.

[0092] Comparative Example 2:

[0093] Based on Example 2, the difference of this example is that in step S4, 2 and 3 ml of polyethyleneimine are added as nitrogen-containing dopants to the obtained SWCNTs mixed slurry, wherein the mass ratio of SWCNTs to PEI is 1:10 and 1:15, 0.883 ml of waterborne polyurethane with a mass fraction of 30 wt.% is added, and the 1:10 and 1:15 slurries obtained after further ultrasonication for 10 minutes are injected into 3*3*0.5 cm 3 The N-type films with different PEI mass ratios were obtained by curing in a silicone mold at 60 degrees Celsius.

[0094] The temperature sensing performance test and valence bond structure analysis were performed on the SWCNTs films of Example 2 and Comparative Example 2 obtained above. The results are as follows: Figure 4 As shown in the figure, the sensitivity of the N-type film increases with the doping ratio. The maximum sensitivity is obtained by fitting ΔVi / ΔT at 1:15. In contrast to the trend of conductivity change, the film prepared by sacrificing conductivity to obtain the maximum sensitivity shows unstable SI value and short equilibrium time under high temperature difference. Figure 5As shown, COC in oxygen element reaches the lowest value in 1:10, proving that the p-type behavior caused by O2 adsorption is overcome. Fitting the sensitive factor content of nitrogen-containing valence bonds, it is found that pyrrolic nitrogen / pyridinic nitrogen reaches a maximum of 1.18 in 1:10, and the combination of carbon tubes and PEI reaches saturation at this time, which optimizes the electron donating ability of N-type SWCNTs as a whole. Therefore, the N-type film obtained in Example 2 achieves the best sensing performance.

[0095] Example 3: Preparation of PON tactile sensor

[0096] 4.66 ml of cellulose nanofibers with a concentration of 5.5 mg / ml and 0.883 ml of 30 wt.% aqueous polyurethane solution were stirred and mixed, and then ultrasonically crushed for 30 minutes to obtain a defoamed uniform O-type slurry, which was then injected into a 3*3*0.5 cm 3 The insulating O-type film was cured at 60 degrees Celsius in a silicone mold. Then the P-type slurry obtained in Example 1 was injected into the upper layer, fully penetrated at room temperature for 400 seconds, and then placed in an oven for drying for 12 hours. The N-type slurry was injected on the reverse side, fully penetrated at room temperature for 400 seconds, and then placed in an oven for drying for 12 hours. Then the polyimide film was used as an encapsulation layer to prevent oxidation and adhered to both sides of the PON to obtain a PON tactile sensor.

[0097] Comparative Example 3: Preparation of PAN sensor

[0098] As a comparative sample of Example 3, the PAN sensor uses an adhesive material acrylic foam to replace the insulating layer O layer, and adheres the single-layer P-type film of Example 1 and the single-layer O-type film of Example 2 to the upper and lower sides respectively. The P-type and O-type films are bonded in series using copper electrodes and conductive silver paste to form a conductive loop; the schematic diagram of PON and PAN is as shown in Figure 6 As shown. Figure 6 As shown, in this embodiment 3, the circuit wiring direction of the PON composite film assembled into a PON touch sensor is on the left and right sides of the upper and lower sides of the film plane.

[0099] The contact angle and sensing performance tests were conducted on the sensors of Example 3 and Comparative Example 3 obtained in different assembly modes. Figure 7 As shown in the figure, the contact angle of the P / N type slurry dripped on the PON dropped from the initial 80.7° to the lowest 48.4° after 400 seconds. In particular, the steep drop in the contact angle in the first 60 seconds revealed a violent penetration process. The P / N type slurry formed a through penetration point in the middle layer, allowing the P type and N type to form a connected series circuit without the need for external electrodes or conductive slurry. Figure 8 As shown, the sensitivity of PON is 1203.6μV K -1Because of the conductive path formed by self-permeation, the sensitivity of PON is increased by 5.0 times compared with PAN, reducing the loss caused by physical stimulation and signal transmission process.

[0100] Example 4: PON tactile sensor can decouple temperature-pressure sensing signals

[0101] Copper electrodes are attached to the left and right ends of the PON tactile sensor obtained in step S7 to perform a decoupling test of the temperature and pressure signals. Fig. 9 As shown in (a), the homemade measurement device is divided into two parts. The PON is placed on the prototype platform, and the right side has an area of ​​0.5*0.5cm 2 The Peltier thermoelectric chip is used to create an adjustable temperature difference. The Mark-10ESM303 mechanical tester is connected above the PON to apply adjustable pressure.

[0102] The performance test of the PON sensor device in Example 4 is performed, as shown in FIG. Fig.10 As shown, the pressure detection range of PON is 0-620kPa, and as Fig. 9 As shown in (b), due to the different sensing mechanisms, on the one hand, temperature stimulation tends to move carriers to form a stable voltage difference. On the other hand, when pressure is applied, the thin film layer structure undergoes reversible deformation, causing the resistance to change. Therefore, the output temperature-voltage and pressure-resistance change values ​​are independent and stable, and the temperature and pressure show good decoupling.

[0103] Example 5: Preparation of smart finger sleeve

[0104] like Fig.11 As shown in the figure, a smart finger sleeve with tactile sensing function is customized according to the shape of the robot hand. The size of the finger sleeve is 2*1cm 2 The two sides of the smart finger sleeve are respectively adhered to the palm and the back of the hand. Copper electrodes are adhered to the left and right ends for connecting to a data recorder to record the voltage and resistance signals output by temperature and pressure stimulation respectively.

[0105] Formulation of hierarchical strategies

[0106] By imitating the hierarchical strategy of the reflective ring, the non-contact thermal sensing signal is transmitted to the computer terminal via wireless Bluetooth transmission, the heat source is located through data processing, and the operation instructions are returned to the single-chip control system of the robot to achieve precise movement or grasping. Finally, the fingertip piezoresistive signal is fed back to adjust the robot operation to ensure accuracy. Fig.12 A flowchart of the decision-making process.

[0107] The temperature and pressure signals output by the smart cuff in Example 5 are as follows: Fig.12 As shown, the tactile capabilities of PON are demonstrated, from accurate positioning of non-contact heat sources to precise touching of objects through controlling operation instructions.

[0108] Compared with the prior art, the present invention has the following beneficial effects:

[0109] First, the solution provided by the present invention forms a dense vertical layered structure through layered polymerization through the joint action of water-based polyurethane and CNF. The compressible nanolayer not only enables PON to respond quickly to pressure stimulation, but also, compared with other special-shaped materials, when i-TE materials are used in temperature sensing, PON can output high thermoelectric voltage values ​​under the same temperature difference; at the same time, the same matrix is ​​used in different layers, and the affinity of the uniform matrix is ​​used to effectively eliminate the interface resistance and contact thermal resistance between layers, thereby reducing the loss in the physical stimulation and signal transmission process.

[0110] Second, the solution provided by the present invention optimizes the carrier content in the system by regulating the optimal proportion of the solid content of SWCNTs in the P-type slurry, thereby achieving decoupling of the two key indicators of sensitivity and conductivity; the saturated doping ratio of the SWCNTs modified sites is obtained by regulating the proportion of the N-type dopant PEI, and then the penetration of the P / N-type slurry in the middle layer is utilized to enable the P-type and N-type to form a connected circuit without the need for external electrodes or conductive slurry.

[0111] Third, the solution provided by the present invention gives the PON tactile sensor extremely high sensitivity and ultra-low detection limit, and also integrates a pressure sensing system with a wide working range, showing excellent cycle stability and pressure-temperature decoupling characteristics under various sensing environments; when worn as a smart fingertip on a robotic hand, it innovatively proposes a bionic cycle strategy of "temperature perception-precise positioning control-fine movement control-real-time pressure feedback-dynamic adjustment and optimization", enriching the functional dimensions of the tactile bionic sensor on the robotic fingertip.

[0112] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above-mentioned technical content without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any changes, modifications, equivalent changes and modifications made to the above embodiments based on the technology of the present invention without departing from the content of the technical solution of the present invention belong to the protection scope of the present technical solution.

Claims

1. A temperature-pressure tactile sensor based on self-infiltration assembly, characterized in that: The tactile sensor comprises a multi-layer composite PON film; the multi-layer composite PON film comprises a P-type sensing layer (2), an N-type sensing layer (4), an intermediate insulating layer (3) and an outermost encapsulation layer (1); the intermediate insulating layer (3) is arranged between the P-type sensing layer (2) and the N-type sensing layer (4); the outermost encapsulation layer (1) covers the outer side surfaces of the P-type sensing layer (2) and the N-type sensing layer (4) to encapsulate the P-type sensing layer (2) and the N-type sensing layer (4); The base material of the P-type sensing layer (2) is water-based polyurethane (WPU), and the active material in the P-type sensing layer is single-walled carbon nanotubes (SWCNTs); The base material of the N-type sensing layer (4) is water-based polyurethane (WPU), and the active material in the N-type sensing layer (4) is single-walled carbon nanotubes modified with polyethyleneimine (PEI); The intermediate insulating layer (3) uses water-based polyurethane without conductive material as a base; The outermost packaging layer (1) is a polyimide film.

2. The temperature-pressure tactile sensor based on self-infiltration assembly according to claim 1, characterized in that: The mass ratio of the base material (CNF) of the P-type sensing layer (2) and the N-type sensing layer (4) to the water-based polyurethane (WPU) is 1:

10.

3. The temperature-pressure tactile sensor based on self-infiltration assembly according to claim 1, characterized in that: The single-walled carbon nanotubes (SWCNTs) account for 5 wt.% of the total solid content of the P-type sensing layer.

4. The temperature-pressure tactile sensor based on self-infiltration assembly according to claim 1, characterized in that: The mass ratio of single-walled carbon nanotubes (SWCNTs) to polyethyleneimine (PEI) in the N-type sensing layer (4) is 1:

5.

5. The temperature-pressure tactile sensor based on self-infiltration assembly according to claim 1, characterized in that: During the preparation process of the multi-layer composite PON film, the pores perpendicular to the film plane are formed by the affinity of the uniform matrix between the layers of the film and the bubbles generated in the bottom aqueous polyurethane.

6. The temperature-pressure tactile sensor based on self-infiltration assembly according to claim 1, characterized in that: A conductive path is formed between the P-type sensing layer (2) and the N-type sensing layer (4) by the self-permeation of the slurry in the middle layer.

7. The temperature-pressure tactile sensor based on self-infiltration assembly according to claim 1, characterized in that: The temperature sensing sensitivity of the multilayer composite PON film is 1203 μV K -1 The minimum detection limit of the multilayer composite PON film is 0.001K; the pressure sensing detection range of the multilayer composite PON film is 0-620kPa.

8. The temperature-pressure tactile sensor based on self-infiltration assembly according to claim 1, characterized in that: The circuit wiring directions of the PON touch sensor assembled with the multi-layer composite PON film are on the upper and lower left and right sides of the film plane.

9. A method for preparing a temperature-pressure tactile sensor based on self-infiltration assembly, characterized in that: The preparation method The process includes: S1: After mixing oxidized cellulose nanofibers (CNF) and aqueous polyurethane solution (WPU), ultrasonic crushing was performed to obtain a defoamed uniform O-type slurry; S2: injecting the O-type slurry into the mold and curing it to obtain a non-conductive intermediate insulating layer film; S3: Then, the single-walled carbon nanotubes (SWCNTs) are dispersed with dimethyl sulfoxide (DMSO), oxidized cellulose nanofibers (CNF), and waterborne polyurethane (WPU) by stirring, and then ultrasonicated to obtain a uniform P-type slurry; S4: Similarly, adding polyethyleneimine in different mass proportions as a nitrogen-containing dopant to the P-type slurry obtained in the above step S3, and obtaining a doped N-type slurry after ultrasonic treatment; S5: injecting and laying P-type slurry on the upper layer of the film obtained in the above step S2, and drying after sufficient penetration to obtain a PO film; S6: Similarly, inject and spread N-type slurry on the lower layer of PO film, fully penetrate and dry to obtain PON composite film; S7: a polyimide film with a thickness of 25 microns is adhered to both sides of the PON composite film obtained in the above step S6 to form a multi-layer composite PON film; S8: The multilayer composite PON film obtained in the above step S7 is adhered to the copper wire with conductive silver paste, and the other end is connected to a data recorder to record the sensing signal obtained by temperature-pressure stimulation.

10. The method for preparing a temperature-pressure tactile sensor based on self-infiltration assembly according to claim 9, characterized in that: In the step S1: 5.5 mg / ml of TEMPO-mediated oxidized cellulose nanofibers (CNF) and 30 wt.% of WPU are stirred and mixed, and then ultrasonically crushed for 30 minutes to obtain a defoamed uniform O-type slurry; In the step S2: inject the obtained O-type slurry into a container having an internal volume of 20*10*3mm 3 The silicone mold was placed in a 60 degree Celsius temperature and cured for 12 hours to obtain a non-conductive intermediate insulating layer film; In the step S3: 13.75 mg of ultrapure SWCNTs and dimethyl sulfoxide, CNF solution were stirred and uniformly dispersed in ultrapure water, ultrasonically crushed to obtain a SWCNTs mixed slurry, and then 0.883 ml of WPU was added, stirred uniformly to fully wrap the SWCNTs dispersed in the slurry, and ultrasonically crushed again for 30 minutes to obtain a P-type slurry; In the step S4: similarly, different weight proportions of polyethyleneimine are added to the SWCNTs mixed slurry obtained in the above S3 as a nitrogen-containing dopant, and the WPU aqueous solution is added, stirred evenly, and ultrasonically crushed for 30 minutes to obtain a doped N-type slurry; In the step S5: inject and spread the P-type slurry on the upper layer of the film obtained in the above S2, fully penetrate for 5 minutes, and then put it into a 60 degree Celsius oven for drying for 12 hours to obtain a PO film; In the step S6: similarly, N-type slurry is injected and spread on the lower layer of the PO film, fully infiltrated for 5 minutes and then dried for 12 hours to obtain a PON composite film.

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