Single-Frequency Amplitude-Modulation Sensor for Dielectric Characterization of Solids and Microfluidics

A microfluidic sensor based on a microstrip line loaded with composite resonator is reported in this paper. The combines shunt connected step impedance (SIR) and complementary split ring CSRR) etched the ground plane. By etching CSRR beneath patch of SIR, CSRR-loaded SIR exhibits two transmission zeros pole between. operating principle variation coefficient at frequency bare resonator, when material or liquid under test (LUT) contact (the sensitive element). designing closely spaced zeros, highly sensors are obtained. Despite fact that proposed can also operate as sensor, using it single-frequency (caused by LUT) specific reduces costs. reason harmonic signal injected to input port microstrip-based plus simple amplitude modulation (AM) detector (connected output port) suffices for measuring purposes. applied characterization volume fraction solutions isopropanol deionized (DI) water. able resolve fractions small 5%, maximum measured sensitivity good 4 mV/%.