Printed RF Contact CPW Sensor for Liquid Detection and Sensing

The resonant frequency of the coplanar waveguide (CPW) antenna depends on the physical dimensions and the dielectric constant of the substrate. In this paper, we have studied the T-type contact printed radio frequency (RF) sensor to detect a class of liquid family with high dielectric constant in the range of 63 to 104. Initially, the relationship between the resonance frequency shifts against various liquids is investigated using high frequency simulation. The T-type sensor was first optimized for only one particular water case then later it was optimized for all considered liquids. The minimum and maximum separation among the considered liquids is 10MHz and 280MHz. To endorse the theoretical and simulation results the sensor was printed using material inkjet printer (DMP-2850). All the liquids were tested by using fabricated sensor and the measurement results showed that resonance frequency of the t-type is changing against each consider liquids. The measurement results were within the expectation of simulated results. The proposed liquid results showed that it could be used as a liquid detection sensor.