Trace water sensor

US4514278A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• James B. Stephens · La Cañada Flintridge, US
• Mary M. Yang · San Diego, US
• Eric G. Laue · San Marino, US

Key dates

• Filing date: Jan 14, 1983
• Grant date: Apr 30, 1985
• Expiry date: Jan 14, 2003

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/423
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A solid electrolytic type hygrometer is described, which operates with high reliability while providing rapid and sensitive response. A gold foil electrode (16) is wrapped about a hollow glass cylinder (18), a sheet (12) of hygroscopic-electrolytic material is wrapped about the foil, and a wire (14) is wound around the outside of the electrolytic sheet. Moisture passing between wire turns can be absorbed by the electrolytic material (12), and then dissociated by current passed by the electrodes (14, 16) through the electrolytic material. The cylinder has a slit (20) extending along its length, to allow resilient expansion to press the sheet of electrolytic material firmly against the electrodes. The wire turns lie against one another to cause rapid dissociation of moisture throughout the electrolytic material. Additional guard wires (42,44, FIG. 2) lie at opposite ends of the electrolytic sheet, and currents pass through them to avoid moisture buildup at the ends of the main wire coil. The electrical current through the sheet or membrane is proportional to the partial pressure of the water-vapor.