Hygrometer capacitive sensor design - with wide humidity range giving accurate measurement and with simple construction

摘要

The hygrometer capacitive sensor has a wide humidity range with high accuracy and is of a simple construction. The sensor consists of a central wire of pure aluminium (21) round which is wound another wire of copper (22). These wires form the electrodes of the sensor, and they are physically though not electrically, attached by a suitable resin. The outer wire (22) is attached to a metal terminal (5) consisting of a tube surrounding the first electrode but isolated from it by an insulating layer (3). The aluminium electrode is 1.016 mm in diameter and the copper wire only 0.0711 mm.