Fabrication And Performance Of Superhydrophobic And Flexible Strain Sensors

In recent years,flexible and wearable devices have become research hotspot.Among them,flexible strain sensors have wide application potential,which are able to be applied in flexible screens,intelligent fabrics and electronic skin,etc.However,at present conductive polymer composites are used to prepare flexible sensors,which might lose flexible property and reduce the sensitive in the wet environment.Therefore,it is important to improve the hydrophobicity of the conductive polymer composites.Hence,polydimethylsiloxane(PDMS)was used as flexible base and hierarchical structure was fabricated on its surface to develop superhydrophobic and self-cleaned properties.Also,PDMS was composited with multiwalled carbon nanotubes(MWCNTs)or silver nanowires(Ag NWs)by different ways to fabricate superhydrophobic and flexible strain sensors.The main researches of this paper were as follow:(1)Preparation of superhydrophobic PDMS.Lotus-leaf or custom mold were used as templates,and PDMS copy the microstructure of the templates.Then,Zn O nanohairs were fabricated on the microstructure by hydrothermal or chemical bath deposition in different conditions.Through SEM and contact angle test,the optimal conditions of fabricating surface hierarchical structure were explored.The result showed that both two methods are capable to obtain superhydrophobic PDMS.Among them,the PDMS which used custom mold and grew Zn O nanohairs in condition of 90?,concentration of grown liquid 0.1 mol/L,grow time 4 h by CBD modified by 8 mmol/L stearic acid,had the best morphology and the maximum contact angle of163.9°.(2)Fabrication of superhydrophobic and flexible strain sensors.Different concentration of MWCNTs and Ag NWs were used as conductive filler and compounded with PDMS as“sandwich”structure.Combining the best condition mentioned in(1),the hierarchical structure was fabricated on the sensors to obtain superhydrophobic and flexible strain sensors.The results show that the0.3 mg/cm~2 PDMS/MWCNTs/PDMS sandwich structure sensor has the best performance,while the PDMS/Ag NWs/PDMS sandwich structure sensor may not have the strain sensing performance due to the thermal failure of silver nanowires.(3)The properties and applications of superhydrophobic and flexible strain sensors.The results show that the sandwich structure strain sensor with the content of 0.3 mg/cm~2 of MWCNTs has the best sensing sensitivity.And its resistance response-bending strain linear fitting degree is good.In addition,it can maintain the superhydrophobic and self-cleaning properties of the surface in simulated different complex water environments.At the same time,it can be applied to detect human motion,which proves its application prospect in wearable devices.