The iThermonitor is a FDA 510(k) cleared wearable thermometer that provides non-invasive, wireless, and continuous core body temperature monitoring for surgery patients. The sensor is worn under the armpit by using an adhesive patch and transmits temperature data via Bluetooth every 4 seconds. iThermonitor’s temperature measurements and the reference esophageal temperature agreed well with the mean bias of 0.14°C with standard deviation (SD) of 0.26 among 80 surgery patients.*
* https://www.ncbi.nlm.nih.gov/pubmed/29293176 Axillary Temperature, as Recorded by the iThermonitor WT701, Well Represents Core Temperature in Adults Having Noncardiac Surgery