Wireless magnetic sensing system for bioengineering application

A wireless temperature sensing system for isolated areas such as those in an organism is proposed. The sensor does not need a power supply within it and is only composed of a temperature-sensitive ferrite core, a wound coil and a chip capacitor. Therefore, the sensor is designed as an LC series circuit. The sensor is driven and signals from the sensor are received by using the loop coil with electromagnetic induction. The system can measure the temperature by receiving a field at the resonant frequency corresponding to the temperature of the sensor. As the inductance of the sensor coil changes with the temperature, the resonant frequency is varied. In addition, we proposed magnetic motion-sensing system using same LC resonant sensor. The magnetic signal of the sensor is detected by pick-up coil array. It can be assumed that the flux density from the sensor is a magnetic dipole field. Therefore, the position and orientation of the sensor can be calculated by solving an inverse problem.