Fabrication And Applications Of Ceramic Nanofibers-based Flexible Pressure Sensor

With the rapid development and application of 5G technology,flexible sensor devices,which are new electronic equipment and human-computer interaction interfaces in the future,have attracted widespread attention.Flexible pressure sensors provide various functions such as physiological signal monitoring,motion detection,and tactile sensing for wearable devices and soft robots,and have important research value.Limited by the types and performance requirements of traditional electronic raw materials,current mainstream wearable sensors are made of rigid materials.Human skin is flexible and humidity-adjustable.Prolonged contact with rigid and airtight materials will cause discomfort and even inflammation.In order to realize sensors that can be comfortably worn by organisms for a long time,it is necessary to make the wearable sensor flexible and improve the breathability of the sensor.Currently,most flexible sensors use polymer materials,such as polydimethylsiloxane(PDMS),hydrogels,ionic gels,etc.These materials have strict requirements on the environments and are prone to degradation under conditions such as high temperature,low humidity,and ultraviolet light,leading to device failure.How to improve the performance stability of flexible sensors in different environments has put forward higher requirements on material selection and device design.Ceramic has the characteristics of corrosion resistance,chemical stability,and high melting point.As a ceramic material with many excellent properties,titanium dioxide(Ti O2)is widely used because of its good biocompatibility and abundance.In this paper,a flexible thin film based on the Ti O2 nanofiber network was prepared by electrostatic spinning.The film has extremely light weight,excellent breathability,and good mechanical flexibility,and is an ideal material for the dielectric layer of a breathable flexible pressure sensor.Based on this material,we designed and fabricated a highly sensitive,breathable,and high-temperatureresistant capacitive flexible pressure sensor.The ceramic pressure sensor exhibits high sensitivity(～ 4.4 k Pa-1),ultra-low detection limit(< 0.8 Pa),fast response speed(response time < 16 ms),and excellent cyclic stability(50 000 compression cycles and 10 000 bending cycles).Further mechanical test results showed that the ceramic nanofiber film has excellent mechanical resilience,resulting in a residual strain of 2.2% after 100 cycles with a 10% compression strain.This is in stark contrast to the irreversible strain of polyvinyl alcohol(PVA)and polyvinylidene fluoride(PVDF)nanofibers,which are 8.0% and 7.4%,respectively.By employing fabric electrodes,a fully breathable and wearable ceramic pressure sensor was successfully prepared.The sensor can be used for real-time health monitoring and motion detection.In addition,the ceramic flexible sensor made of high-temperature-resistant carbon fiber electrodes can achieve high-temperature applications.At 370 ℃,the sensitivity of the sensor reaches 0.028 k Pa-1,and it can withstand a transient high temperature of about 1300 ℃,showing its great application potential in extreme environments.