Toward wearable wireless thermometers for internal body temperature measurements

This article overviews the motivations and challenges for non-invasive wireless measurements of internal human body temperature. Microwave radiometry is an attractive method for internal thermometry, with the possibility of a wearable device that can continuously monitor temperature inside body tissues in different parts of the body, store the data, and transmit it to a digital medical record. Currently, there are a limited number of available device solutions, and they are usually not wearable or wireless. Here we discuss a possible path to implementing such a thermometer, with some initial results demonstrating about 0.2 K measurement sensitivity, and a difference between the maximal and minimal error w.r.t. a thermocouple measurement of 0.5 K. Several probes for multi-band radiometers are also presented at frequencies of 410 MHz, and 1.4, 2.7, and 4.9 GHz. The main challenges of RF interference, sensitivity, calibration, spatial resolution, miniaturization, and probe design are discussed.