Design And Application Of Flexible Self-powered Temperature Sensitive Unit

With the development of micro-energy technology,flexible self-driving electronics have become a strategic cross-over height that cannot be ignored ground for new sensor units.However,the traditional temperature sensor unit is limited by the external power supply,which has a series of shortcomings such as hard material,non-portable and long-term battery replacement.Therefore,it is an important step to change the traditional temperature monitoring method and give the monitoring equipment the functions of portable,remote and real-time monitoring.Recently,increasingly mature triboelectric and pyroelectric micro-energy harvesting devices have attracted worldwide attention in the field of self-driven sensing due to their soft materials,good portability,and no need for external power sources.Temperature sensitive materials based on different sensing mechanisms have relatively mature exploration,but it is difficult to realize no external power supply in temperature sensing testing,which has become a major challenge in the field of flexible self-powered sensing.Although the traditional temperature sensor has achieved certain temperature monitoring characteristics,it cannot achieve portable,real-time and remote temperature monitoring,which is undoubtedly a fatal weakness in the realization of intelligent electronic devices.To this end,the triboelectric and pyroelectric materials based on capturing the environment or human thermal energy and converting it into electrical energy,provide practical application guarantees to solve the environmental temperature,human respiratory heat and oral temperature sensitive unit energy supply limitation.Based on the new flexible temperature sensitive materials and the real-time monitoring application requirements of environment/human body temperature,this paper makes the following summary:(1)A self-powered temperature sensing unit based on the triboelectric mechanism of polyvinylidene fluoride(PVDF)and polytetrafluoroethylene(PTFE)is proposed and fabricated.The pyroelectric property of PVDF can be used to enhance the charge density on the contact surface of triboelectric layer,which can be used as a self-powered temperature sensitive unit.Ag electrode on the surface of PVDF is used as the bottom electrode layer and triboelectric layer.PTFE as the top triboelectric layer is connected with the top electrode conductive copper foil.Meanwhile,the spacer layer(Kapton)with hollow structure is placed between the PTFE film and Ag electrode to form a cavity structure,which provides a guarantee for the cold and hot alternation of the temperature monitoring process.The results show that the output voltage of the sensor increases linearly with the temperature in the range of 295-335 K.And its temperature response time was approximately 100 ms.It has excellent stability in 5500 periodic contact separation cycles.(2)The triboelectric temperature sensitive unit is essentially in body contact and is not suitable for portable respiratory heat signal monitoring.Therefore,to optimize the structure of the self-powered temperature-sensitive device,a flexible physiological information monitoring device with a non-contact test method is proposed and prepared.This non-contact test solves bottlenecks such as non-portability and discomfort in the monitoring of wearable human physiological information.And the experimental measurement shows that the flexible pyroelectric sensor can generate linear pyroelectric signal(R~2=0.9923)in the temperature range of 295-355 K.Furthermore,based on the natural temperature oscillation between the living body and surrounding environment,the sensor can realize human physiological information assessment.For example,the temperature monitoring of palms,fingers and mouth,and the electrical response law of nose respiratory frequency under different movement conditions(normal breathing and post running breathing),and the non-contact space thermal mapping recognition of finger movement by a 3 X 3 sensor array.At last,the practical application of the non-contact flexible temperature monitor and wireless transmission technology is explored.It verifies that the temperature sensitive system has the ability of remote(10 m)nose or oral breath wireless monitoring.The ability of wireless physiological information monitoring is an important step to establish a long-distance intelligent information bridge between doctors and patients to assess the physiological status of individuals.