A flexible force-sensitive film with ultra-high sensitivity and wide linear range and its sensor

Abstract

Flexible force-sensitive sensors are widely used in wearable devices, electronic skins, human-computer interaction and other fields due to their simple manufacturing process, low cost, strong flexibility and great integration potential. A new type of FeSiBY amorphous alloy flexible force-sensitive film and its sensor has been developed in this paper. The film had high elastic modulus, microhardness and higher phase transition temperature. The piezomagnetic effect of this new type of film was significantly better than the Fe78Si13B9 amorphous alloy film currently used. The single-layer FeSiBY film exhibits a linear change in the micro-stress range of 0–1.2KPa, and the sensitivity was as high as 88.87μH/KPa, which was far better than Fe78Si13B9 amorphous alloy film’s (the highest was only 0.52μH/KPa). By increasing the number of film layers, the linear range of the piezomagnetic curve of the film can be effectively broadened. The upper limit of the linear range of the piezomagnetic curve of the sensor after 4 layers of films was superimposed reaches 16KPa, and the sensitivity still reached 6.84 μH/KPa. In the area of linear change of the piezomagnetic curve, the loading piezomagnetic curve of FeSiBY film was highly consistent with the unloading piezomagnetic curve, and there was no elastic hysteresis. Meanwhile, the environmental temperature had little effect on the piezomagnetic curve. The piezomagnetic sensor composed of FeSiBY film had the advantages of high sensitivity, wide sensing range, fast response speed, strong anti-interference ability and good repetitiveness, it can be used to test both static compressive stress and dynamic compressive stress and can meet the requirements of subtle stress detection and complex surface test. The sensor was applied to a variety of human physiological activities (such as pulse, pronunciation, joint bending, etc.) with good results. This flexible force-sensitive film sensor has broad application prospects in wearable electronic devices and health monitoring. This article provides a simple, low-cost, and strong anti-interference solution for making flexible film sensors with good force-sensitive properties.