| In recent years,in order to simulate the tactile perception of the skin,researchers have constructed flexible pressure electronic skin arrays based on different conduction mechanisms and structural designs,and achieved surprising results in how to improve the sensitivity and detection range of the sensors.However,as a bionic device simulating human skin,electronic skin needs not only the pressure sensing function,but also the ability to simultaneously detect temperature,humidity and other complex environmental changes,so as to help us communicate with the surrounding environment and maintain the balance between human body and the surrounding environment.Among them,temperature and pressure are the two most common tactile stimuli.Although a lot of work has been done in temperature sensing and pressure sensing,it is still a huge challenge to detect and distinguish temperature and pressure simultaneously due to the compatibility,structural design and production cost limitations among sensors with different functions.Therefore,further research is needed to develop high-performance,high-resolution electronic skin that can detect both temperature and pressure.This project mainly uses polyvinylidene fluoride(PVDF)and polyacrylonitrile(PAN)as raw materials,and uses electrostatic spinning technology and heat treatment technology to prepare PVDF/Zn O NPs composite nanofiber membrane with pressure sensing characteristics and PAN-based carbon nanofiber membrane with temperature sensing characteristics.The optimal doping content of Zn O NPs in the preparation of PVDF/Zn O NPs composite fiber membrane was investigated.The results showed that when the content of nano zinc oxide was 1wt%,the VOC,ISCand Q of the composite fiber membrane added with nano zinc oxide increased to 3.24 V,21.49 n A and 1.36 n C compared with the pure PVDF fiber membrane(0.94 V,5.33 n A and 0.44 n C),and the piezoelectric coefficient reached the maximum value of 65.96 p C/N.The PVDF/1%Zn O NPs composite fiber membrane and carbon nanofiber membrane were integrated vertically into a multifunctional electronic skin sensor.The test results showed that the pressure sensitivity of the device was 15.77 m V/k Pa and 52.90 m V/k Pa within the pressure range of 10-25 k Pa and 25-45k Pa,respectively.The maximum power density of the device was 17.1 W/m2,and it could run continuously over 5000 working cycles,showing good durability and repeatability.In the wide temperature range from 25°C to 100°C,it exhibits negative temperature behavior,temperature sensitivity is close to 0.381%/°C,and shows fast response ability,excellent cycling stability and good repeatability.The device is further used to respond to external pressure and temperature,such as sensing weights of different weights,finger pressing,grip strength test,monitoring water temperature change,etc.These prove that the electronic skin sensor has the ability to sense weak pressure and continuously monitor temperature change.This accurate measurement provides great potential application value in the field of human-computer interaction and intelligent prosthesis.In addition,the device can keenly detect the radial artery pulse signal of an adult man,showing its heart rate and radial artery enhancement index of 80 beats per minute and 75%,respectively,which reflects the device's excellent detection performance and high sensitivity,and proves its application possibility in the field of medical diagnosis.Finally,the electronic skin sensor is prepared into a16-pixel electronic skin array,which can distinguish the approximate shapes of letters"D","H"and"U".A single touch test was carried out,and the sequence of each voltage signal channel in the tester was consistent with the finger touch path.These prove that the e-skin array has the ability of shape recognition and real-time sliding trajectory recognition,which means that it has a good application potential in artificial intelligence field. |
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