Fabrication And Application Of High Transmittance Electronic Skin Based On Polymer Piezoelectric Membrane

As the largest organ of human body,skin can transmit external stimuli and convert them into signals that the body can perceive,such as pressure,pain and temperature.Therefore,it is very necessary to prepare an electronic skin device that simulates human skin,and explore its application value and application means through reasonable analysis of the collected signals.After years of research and practice,electronic skin is becoming more than skin itself.In terms of technology,electronic skin plays an important role in artificial limb manufacturing,robot design,wearable devices and other fields.However,as a new technology,the preparation of electronic skin is difficult to achieve industrialization due to high material cost and large area preparation.The low transmittance of electronic skin also makes it difficult to make a breakthrough in touch screen and other application fields,so it needs further improvement and improvement.This topic mainly focus on the electronic skin of low cost,can be prepared in a large area,high transmission and other performance requirements,using a relatively low price of piezoelectric material--polyvinylidene fluoride(PVDF)preparation of electronic skin;electrospinning method is used to overcome the difficulty of large-area fabrication of devices;the transmittance of the film was improved by controlling the spinning time.The specific research contents are as follows:1.PVDF piezoelectric membrane was prepared by electrospinning method,which realized two advantages of electronic skin preparation: electrostatic spinning method can avoid the secondary polarization process of film preparation,and also can realize the large area of film preparation;the piezoelectric properties of PVDF can be used to realize self-power supply of devices,which improves the portability of electronic skin.The effect of different concentration of PVDF solution on the nanofiber membrane was compared,and the PVDF solution with a concentration of20 wt% was selected to prepare the nanofiber membrane.The results of XRD and FTIR show that the piezoelectric films prepared by this method have excellent piezoelectric properties,the content of β crystal is 82%,and the open circuit voltage of 8 V and short circuit current of 0.8 μA can be generated;2.The silver nanowire electrode was prepared with highly flexible polydimethylsiloxane(PDMS)as the substrate,and the resistance of the electrode was less than 100 Ω.By integrating the flexible electrode and PVDF nanofiber membrane,the sensitivity of the device reaches 122 m V/N.The electronic skin can be attached to the finger without extra glue and can generate electrical signals based on changes in the amplitude of finger movements.After four hours of wearing,the skin did not peel off and its signal output was not affected;3.In order to realize the high transmittance of electronic skin,the pore quantity of PVDF nanofiber membrane was reduced by controlling the electrospinning time,so as to improve its light transmittance.The electrospinning time was controlled between5-20 min,and the relationship between transmittance and open circuit voltage of PVDF nanofiber membranes under different spinning time(different thickness)was compared.It is found that under the same compression force,the increase of the film thickness will increase the open circuit voltage and decrease the strain level of the deformed fiber,thus affecting the power generation performance of the nanofiber membrane.Under this rule,after comparison of 7 groups of parameters,the selected optimal film has an open-circuit voltage of 8 V and a transmittance of 78%.The membrane is combined with a transparent electrode to form an electronic skin,which has little effect on the clarity of the device when it is overlaid on the pattern,and the energy generated by pressing the device can light up a small screen.It shows that the high transmittance electronic skin prepared by us has a certain development potential in the field of touch screen energy storage.Through theoretical analysis and sensing performance test,it is proved that the electronic skin device of this subject has the characteristics of simple preparation method,high sensitivity,high light transmittance,etc.The prepared device can collect the information of human hand movements,and can also use its high transmittance to attach to the touch screen to collect energy,which plays a certain role in expanding the application field of electronic skin.