Polymer hygrometer for harsh environments

Claim 1

A sensor for deriving data incidative of relative humidity and temperature of air in drier ducts, ovens and so forth comprising a lithium-doped Nafion strip mounted across two glass capillaries embedded in a Teflon base, with the ends of said Nafion strip embedded in a filling of conducting silver-filled epoxy; said filling also providing electrical connections to a pair of gold coated brass pins through platinum wires also embedded in said filling; a temperature sensor mounted across another pair of pins located on said base on a line at right angles to a line joining said first pair of pins; multi conductor cables which connect said sensors to two measuring circuits; one of said circuits comprising means for power, square wave generation, buffered amplification, inversion, perfect rectification and means for amplified output, which produces an output voltage or current proportional to the conductance of said Nafion sensor; the other said measuring circuit producing an output proportional to temperature of said temperature sensor; a tubular shield with porous ends in which said sensor is housed to prevent excessively high speeds air from blowing directly on said sensor; output means for displaying outputs from said measuring circuits, calculating relative humidity and temperature and generating useful control signals to utilize said calculated relative humidity and said calculated temperature of air in said duct or oven.