A New Readout System for LC Resonant Sensors

A new readout system based on LC resonant sensor is presented. The readout system consists of a reader coil inductively coupled to the LC resonant sensor, a measurement unit, and a PC post processing unit. The measurement unit generates an output voltage representing the sensor resonance, converts the output voltage to numerical form, and saves the converted digital data. The PC post processing unit processes the digital data and calculates the sensor's resonance frequency. The readout system enables wireless interrogation and its accuracy is exemplified by an experimental system. The experimental system can detect the resonant frequency of sensor automatically and effectively. The experimental results are presented for different sensor resonance frequencies with various sensor capacitance values and show good agreement with the theoretical results. The entire design is simple, easy to use, and widely applicable for applications where the coupling distance between sensor and reader coil is variable.