EgbertMIT engineers have developed an ingestible sensor (6 by 4 mm) that can send continuous temperature updates from the GI tract. It can detect temperature with an accuracy of 0.01 degrees Celsius and requires very little power — about 10 nanowatts.
https://news.mit.edu/2026/tiny-ingestible-sensor-can-measure-temperature-inside-body-0615
