Mass Communication Specialist 3rd Class Adam Henderson/US Navy
A Navy SEAL climbs up a ladder attached to the side of a gas and oil platform during training to prepare an upcoming deployment.
For the last 25 years, the US military has used an ingestible thermometer pill to monitor the core body temperature of service members during physically demanding missions.
CorTemp pill (HQ, Inc.) was developed in the mid-1980's by the Johns Hopkins Applied Physics Laboratory and the Goddard Space Flight Center.
The sensor technology was first used on astronauts to detect hypothermia and hyperthermic conditions during space flight.
Here is how the pill works: Soldiers swallow a 3/4-inch silicone-coated capsule which contains a microbattery and a quartz crystal temperature sensor.
Within two hours, the quartz crystal sensor vibrates at a frequency relative to the body's temperature and transmits a harmless, low-frequency signal through the body.
A Navy corpsman can then wirelessly monitor the core body temperature of multiple subjects in real time. There are several options and configurations for tracking temperatures, including the most simple method of holding the data recorder near the small of the back.
The pill safely passes through the digestive system after 18 to 30 hours. The $50 pill is used at Special Warfare Combatant-craft Crewmen (SWCC) training facility in Coronado, Calif. where candidates swim in open sea ranging from frigid 48 degrees Fahrenheit to 72 degrees Farenheit.
"For SWCC personnel, the pill is used to monitor body core temperature and is used only in training. Its use ensures candidates can understand the impact of cold water and allows medical and training cadre staff to ensure safety parameters for training are observed," Navy Lt. Ben Tisdale told Business Insider via email.
The ingestible capsules are also used by the NFL, various European militaries, and fire departments in the United States and in Australia, according to Director of Sales & Marketing, Lee Carbonelli.