In medical and nursing care, body temperature measurement is required for daily health management. In particular, its importance has been well-recognized for the prevention of thermoregulatory failure in patients with spinal cord injuries and for early detection of pneumonia in bedridden elderly. However, commercially available axillary and oral thermometers are cumbersome for such patients as well as for the care staff who operates the devices, because of the need to attach the biological sensor to the patient’s body. This paper describes a new attempt at developing a non-intrusive system for measuring body temperature. While the care staff helps the patient change posture to prevent pressure ulcers, temperature is measured when the bed sheet makes contact with the subject’s body. In this method, three sensor modules, each comprising a thermistor, a resistance-sensitive pressure sensor and a heat insulating material, are installed in the bed sheet and positioned under the subject’s left scapula, celiac plexus, and waist. The body temperature can be estimated from the rate variation of temperature increase immediately after the pressure sensor detects that the subject has laid down on the bed. Comparison of the body temperature obtained from the prototype bed system and that measured by a commercially available axillary thermometer in nine adults (aged 20-98 years) demonstrated that the proposed method may be useful for body temperature measurement. However, improvement in positioning the sensor modules is needed for detailed and continuous analysis of health condition.
