Self-Powered Pressure Sensor Based on Flexible Permanent Magnet Material

This work presents a self-powered pressure sensor based on flexible permanent magnet material. The sensor consists of a square spiral coil and magnetic material, which operates on electromagnetic induction. The flexible magnetic material is developed with the foaming agent ammonium bicarbonate (NH4HCO3). The magnetic characteristics and the mechanical properties of the magnetic component are greatly related to the ratio of NH4HCO3 and neodymium-iron-boron (Nd2Fe14B) doped in polydimethylsiloxane (PDMS). A semicircular hollow structure is proposed to improve the sensitivity and linearity of the sensor. This sensor is sensitive to dynamic forces and with high output voltage and fast response speed when the force is applied. The way that the force is applied affects the amplitude and the rising time of the voltage pulse generated in the sensor due to changes in the magnetic field created by flexible magnetic materials. Additionally, a portable testing system is built for performance testing. To meet the requirement for noncontact testing, the sensor can be separated into two components. A sensor array with a semicircular hollow shape has been constructed and can be worked as a counter. These applications indicate that this sensor can be used to identify human movement.