Vapour measurement is no damp squib

A new simple-to-use system accurately measures the movement of water vapour above the human skin. According to Professor Bob Imhof, his team's AquaFlux sensor solves a problem which has challenged bioengineers for the last 50 years. Developed to establish skin health, it is also ideal for detecting sources of damp in buildings as well as the effectiveness of food packaging and sports clothes. It has long been known that the flux of water through human skin is a measure of how good a barrier it is and therefore how healthy it is. Talking to Eureka in his South Bank University office, Professor Imhof explained that, "all sorts of fancy apparatus has been used in the past". The most popular method has apparently been to place two chip humidity sensors inside an open ended tube, place the tube on the skin, and hope that external air currents will not cause too much upset to the diffusion gradient inside. The AquaFlux, on the other hand, uses a tube which is open at once end, but closed at the other, to exclude draughts, and only a single sensing chip. A humidity gradient is ensured by placing a Peltier cooler on the closed end, so that water vapour reaching it is condensed as ice by the -7°C temperature. If the surface under study at the other end is wet, it is first dried so that the only water vapour moving up the tube is that emanating from beneath the surface. The measurement chamber is 7mm internal diameter and 16mm long. Coupled to a PC, the sensing probe yields answers in less than a minute. As well as the health of skin, it can measure dampness emanating from walls, as opposed to the dampness already inside a building, in order to locate the source of a problem. The first sale, however, was to a textile research institute. The AquaFlux is available from South Bank University spinoff company, Biox Systems. It won Professor Imhof the BT Award for Technical Innovation at the London Innovation Awards 2002. The present cost is around £10,000 but there is no technical reason why the technology could not one day be built into sensing systems, costing very much less, which could be used for improving climate control in both buildings and cars. Biox Systems Professor Imhof h keywords: sensors, humidity Biox Systems Enter XXX Pointers D/T/A-Text: The sensor enables the accurate measurement of the flux of water vapour emerging from a surface D/T/A-Text: Using a closed sensing tube, it is immune to effect of draughts D/T/A-Text: Its applications include medical diagnosis of skin conditions, location of sources of damp in buildings and evaluation and testing of fabrics