A small pliable humidity sensor, with special reference to the prevention of decubitus ulcers

In an investigation of some of the external causes of decubitus ulcer, a small flexible sensor has been developed as a clinical device to measure the relative humidity (RH) of the environment between the patient and the surface on which he lies. The sensor (described in detail) can indicate RH in the range of 20 to 90 per cent by a color-matching method (chemically impregnated circles); accuracy is within 5 to 10 percent. In a preliminary study on 28 patients, the readings showed that RH was higher in the sacral region than in the scapular region, and higher for patients who were inactive than for those who were active. The device was well accepted by both patients and nurses.