A Resonance-Induced Sensitivity Enhancement Method for Conductivity Sensors

We demonstrated in this paper a novel technique named resonance-induced sensitivity enhancement (RISE) method to be used for significantly improving the sensitivity of a variety of conductivity sensing devices. The technique works by introducing a parallel inductor to the conductivity sensor cell and operating the sensor system at the resonant frequency of its equivalent circuit model. At the resonant frequency, parasitic capacitances that are either in series or in parallel with the target conductance can be virtually removed from the equivalent circuit and therefore a much higher sensitivity to the target conductance is obtained. In a specific example, the sensitivity of a microchip capacitively-coupled contactless conductivity detector (C⁴D) can be improved by more than 10,000 times.