Based on the RFID sensing technology, A flexible strain sensor has been developed based on the LC circuit where the capacitance is considered as a sensing unit. To increase the sensor sensitivity, nano cracks have been introduced to the electrodes to create a piezoresistive effect that leads to a transmission line behavior of the capacitance. The unconventional change in capacitance of the LC oscillator reflects a sensitive
shifting in resonance frequency of the flexible circuit, producing a sensitive wireless strain sensor with a Gauge factor of 50 for less than 1% strain.
