CAPACITIVE HUMIDITY TRANSDUCER

Of all the basic environmental variables, only humidity has resisted simple, reliable measurement. Hygrometric elements have always had limitations in their useful application, especially with regard to their inability to be stable and durable. Here, the rationale behind the development of a capacitive-type sensor is presented along with the functional and electrical characteristics to encourage confidence in the basic mechanism. With a one percent change in the capacitance in the nanofarad range for a one percent change in relative humidity, the element exhibits good linearity and negligible temperature dependence over environmental ranges. Exceptional stability and ease of utilization will permit application of this transducer to the broadest of humidity monitoring and control problems. Copyright © 1969 by The Institute of Electrical and Electronics Engineers, Inc.