| Wearable electronic devices are expected to bring significant changes to human life in the future.As the core component of wearable devices,flexible electronic sensors have gradually become a research hotspot in the fields of electronic science,material science,and other fields in recent years.Traditional wearable sensors are mostly passive components,requiring larger batteries as the energy supply for the sensing system.To solve this problem,active sensors that can generate electrical signals as a response to environmental changes have emerged.In this thesis,liquid metal is selected as the core sensing functional material of flexible sensors,avoiding the defects of traditional solid conductive materials,and a liquid metal pattern preparation method is designed.Finally,based on this liquid metal coil,a flexible active sensor device that can be used to measure the magnitude of external pressure and the mode of external pressure application is designed.The main research content of this article can be divided into the following four aspects:(1)Liquid metals with excellent electrical conductivity have excellent fluidity at room temperature,which makes them have an important application prospect in the field of flexible stretchable electronics.However,their deep application still needs to solve the bottleneck of micro and nano fine machining caused by high fluidity.In view of the manufacturing and packaging difficulties faced by the micro-nano graphics and functionalization of liquid metal,this thesis proposes a micro-nano processing technology for manufacturing hundred-micron metal coils by three-dimensional additive for gallium indium tin liquid metal through extraction and improvement of key process parameters,design and optimization of micro-nano structure,and realizes the liquid metal graphics with sensing function.(2)Aiming at the problem of high power consumption of flexible passive sensors,an active pressure sensing mode based on electromagnetic and eddy current effects was proposed.A flexible active sensor composed of silicone air elastomer,neodymium iron boron permanent magnets,and liquid metal coils was designed.In order to complete the performance characterization of the flexible sensor,an active sensing test system was built,and a controllable and stable circulating pressure application platform was realized.To verify the active sensing function of the device,the peak power of the device was measured up to 27 μW at a pressure application frequency of 5 Hz,and stable operation during 17,000 press cycles.(3)A pressure sensing mechanism based on eddy current effect was studied based on the stress-deformation relationship between silicone and air elastomers.In order to verify the feasibility of the sensor as a wearable component,a portable pressure size test platform was built.The maximum sensitivity of the measured device was 0.255 μH/N,and the human body weight was monitored.(4)Combined with the elastic recovery mechanism of silica-air elastomers,an active sensing mechanism for pressure pattern detection based on electromagnetic induction effect was studied.In order to verify the active pressure sensing function of the device,the current output waveform of the device driven by different external pressures was tested and analyzed,and the discrimination of different human motion states such as walking,running and jumping was realized in the wearing test. |
