Capacitive chemical sensor for detecting certain analytes, including hydrocarbons in a liquid medium

Abstract From the Canadian patent

An apparatus for detecting the concentration of certain analytes, including hydrocarbons, in a liquid medium is disclosed. The apparatus uses a planar or "open" capacitor containing an active layer. In response to selected analyte in the liquid medium the, active layer causes capacitance to decrease with increasing analyte concentration. The capacitance decreases because higher dielectric water molecules are displaced from a region of the capacitor's electric field. For certain hydrocarbon analytes having high Henry's Law constants, the active layer causes bubbles to nucleate in the liquid medium on the surface of the active layer. Bubble formation displaces water molecules and decreases …