Development of a LC Passive Wireless Sensor Utilizing Capacitively Coupled Contactless Detection Structure

This paper presents the results on developing of a LC passive sensor utilizing capacitively coupled contactless detection structure for detection of defect inside a flow in miniaturized fluidic channel. The sensor operates based on the change in capacitance of the coupled capacitor when having a defect in the fluidic flow which results in the change of the resonance frequency of LC passive sensor. By monitoring the change of resonance frequency of the LC sensor, the presence of defect, i.e., an air bubble, in the fluidic flow can be detected. The distance between antennas has also been manipulated for finding the optimal configuration of the sensor. The dependent of resonance frequency change on the size of air bubble, as well as the location of air bubble has been investigated and analyzed. Experimental results show that the resonance frequency shifts up to 1.5 MHz correspond to the presence of an air bubble with volume of 196 nL in the flow.