Detection of volatile organic compounds using microwave sensors

A microwave (MW)-based sensing platform for detection of acetone vapor is demonstrated. The sensing platform comprises of an MW resonator coated with a thin layer of polydimethylsiloxane (PDMS) that acts as a sorbent layer for acetone. Absorption-induced swelling of PDMS changes the permittivity and results in reproducible variations in the resonance frequency of the resonator. Here, we demonstrate the detection of acetone, as the model analyte, with the concentrations of 0-265 ppt. In addition, since the technique is based on electromagnetic fields spilling into space, we show the ability of the sensor to detect acetone in a noncontact fashion.