Upgraded humidity sensors are compact and economical
Upgraded humidity sensors are compact and economical
Keywords Humidity,Radiatron, Sensors
A second-generation atmospheric humidity sensor offering significant space and cost savings as well as fast, reliable action has been introduced by UK-based Radiatron. Manufactured by Elmwood Sensors, the ERH-200 humidity sensor comes in a compact package 15mm square x 5mm deep, and costs around 30 per cent less than the larger ERH-300.
Conventional humidity sensors of various types are widely used to control dehumidifiers, extractor fans and air conditioning equipment in offices and homes, and in process control tasks involving fine powders in the food and pharmaceuticals industries. However, new high-volume applications in the design of intelligent "white goods" such as microwave ovens and tumble driers that switch off automatically before their contents are baked dry are driving demand for higher sensor functionality in a more compact, economical package.
The ERH-200 series represents a second generation of humidity sensors developed through research collaboration between Elmwood and Durham University. Sensing is carried out via a doped zinc tin oxide ceramic layer whose electrical resistance changes with the humidity of the atmosphere, due to absorption of water vapour into the crystal structure.
As this resistance effect occurs at the molecular level, the sensor offers a faster response to humidity changes than conventionalpolymer-based devices which rely on a "sponge" effect. The ERH-200 responds to humidity changes within seconds, compared to minutes for a conventional polymer device.
Other benefits of this technology include tolerance to airborne contaminants such as smoke, solvents and aerosol particles, which clog the pores of polymer "sponges"; stable accuracy of around 4 per cent relative humidity without the need for recalibration; and an extended operating temperature range of 20°C to+ 110°C.
The ERH-200's cost and size advantages over the larger but more accurate ERH-300 series derive essentially from improvements in print technology, which have reduced the length of tracking required for the sensor electrodes.
For further information contact: John Roe, Radiatron, Tel: +44 (0) 1784 439393; Fax: +44 (0) 1784 477333.
