Preparation Of Acrylonitrile-based Flexible Piezoelectric Material And Application In Wearable Sensor

Real-time monitoring of biomedical signals provides tremendous convenience for our modern lifestyle.The wearable device can monitor and recognize physiological signals(heart rate,blood pressure,respiratory rate and stride frequency,etc.).However,conventional real-time monitoring devices have serious drawbacks,such as rigid structure,poor sensitivity,resulting in many limitations in daily life and medical applications.Therefore,this starts from wearable devices,and prepares flexible sensors and focuses on their responsiveness,stability and sensitivity.In this study,an elastomer with excellent mechanical resilience and electrical electrical responsiveness was prepared by copolymerizing acrylonitrile with sodium p-styrene sulfonate.The microstructure of the elastomer had a two-way pleated structure.After compressing the mechanical cycle for 100 times,the stress-strain curves of the elastomer are basically coincident,and the stress-strain hysteresis loop was small,indicating that the elastic body of the two-way pleated structure has excellent energy consumption dispersion mechanism.The experiment of outputting electric signals under different external forces showed that the elastomer has excellent electrical and electrical responsiveness and can accurately distinguish the external force.The output electric signal was tested by the external force of 5N cycle.The output voltage of the first 10 times was 70 mV,the intermediate voltage output of 400 times is 70 mV,after 740 cycles of compression,the voltage output value droped slightly to 67 mV,which was equivalent to the initial voltage output value,indicating that the elastomer had stable electrical properties.The sensitivity,accuracy and stability of the elastomer used as flexible sensing were verified by pulse,stride and air blowing experiments.The study made new explorations for the development of the next generation of wearable electronic devices.Polyvinylidene fluoride(PVDF)is a superhydrophobic piezoelectric polymer that is often limited in biosensors.In this study,a flexible piezoelectric pressure sensor was fabricated by combining PVDF with a flexible substrate hydrogel.It was confirmed by infrared,XRD and DSC characterization that PVDF in the composite hydrogel mainly existed in the β phase.Characterization of the force and electrical response of the sensor indicated that the sensor had stability,accurate force electrical responsiveness.Experiments on the force and responsiveness of the output voltage of the flexible sensor by the angle of the finger bending angle and the sound intensity of the vocal cord confirmed that the sensor has stable and accurate force and electric responsiveness,indicating that the sensor has potential application as a flexible sensor.The design and use of flexible sensors implanted in the body provides new ideas.