Development Of High Sensitivity Flexible Temperature Sensor And Its Systems Based On PNNs

In recent years,with the improvement of living standards,people's health awareness is gradually increasing.As one of the most important physiological parameters in human body,temperature can not only provide a scientific basis for the evaluation of health and cognitive status,but also provide significant clinical guidance for the prevention and control of infectious diseases such as new coronavirus and swine flu through real-time and accurate monitoring.Existing temperature measuring equipment is usually based on hard materials that are unsuitable for continuous realtime dynamic monitoring,while the flexible temperature sensors show the advantages of tight fit,high stability,and strong anti-interference ability which can quickly grasp the change of body temperature and has great application prospects.However,the reported flexible temperature sensors still have the disadvantages of low sensitivity and complicated fabrication processes.Based on the above background,we innovate from materials and structures of flexible temperature sensors.High-quality layered molybdenum disulfide(MoS₂)nanosheets,which were prepared by the liquid phase ultrasound method,were used as temperature-sensitive materials.A field-effect transistor(FET)was constructed with porous MoS₂ nanonetwork,which would effectively increase the area of the double electric layer.The intrinsic detection mechanism of the temperature sensor was deeply explored.Finally,we successfully obtained a high-performance flexible temperature sensor based on porous nano network,together with a real-time temperature monitoring system.The main research contents include the following aspects:1?In this study,layered MoS₂ nanosheets were applied to the field of flexible temperature sensor,and a flexible temperature sensor based on MoS₂ porous nanonetwork was successfully developed.We introduced an electric-double layer fieldeffect transistor as the structure of the flexible temperature sensor and thus,the sensitivity of temperature detection was effectively improved due to its amplification function.The MoS₂ nanosheets were firstly prepared by liquid-phase ultrasonic method.The porous nanonetwork with high porosity was formed by a low-cost solution method and used as the semiconductor channel of the FET.The network was in contact with the ionic gate dielectric layer to form a composite structure with a double electric layer interface involved of a large capacitance.Utilizing positive temperature correlations of the double electric layer capacitance and the carrier mobility of MoS₂,we successfully achieved high sensitivity detection on temperature.2?In this paper,the influence of the gate dielectric layer on the temperature detection performance was deeply studied.We found that the solid / solid structure,which was formed by the MoS₂ porous nanonetwork and solid-state gate dielectric layer ion gel,had some problems such as large output current noise and low resolution.This was due to the polymer cross-linking agent existing in the gate dielectric layer that severely limited ion transports.Consequently,we replaced solid / solid structure with solid/liquid structure formed by the MoS₂ porous nanonetwork and liquid-state gate dielectric layer——ion liquid,due to the improvement of ion mobility,the problems of current noise and work stability were effectively solved.The device shows excellent performance on temperature detection,with a sensitivity of 7 %/? and a resolution of 0.1 ? in a temperature range from 20 ? to 80 ?.3?Based on the flexible temperature sensor,we successfully developed a realtime temperature monitoring systems containing hardware circuit and software program.The hardware circuit was used for collecting and processing of output current signals from the FET and thereby,to obtain corresponding body temperature data;the software program,which was developed from Eclipse platform,was able to achieve remote display and storage on temperature data.The flexible temperature sensor and its system developed in this paper are not only expected to play a role in the field of body temperature monitoring but also have certain application potential in fields of electronic skin,flexible robots and so on.