MIT Engineers Develop Tiny Ingestible Thermometer for Continuous Core Body Temperature Monitoring

Engineers at the Massachusetts Institute of Technology (MIT) have engineered a groundbreaking ingestible temperature sensor, measuring a remarkably small six by four millimeters. This innovative device is designed to overcome the limitations of conventional thermometers, such as oral and forehead models, which often fail to accurately capture a person's true core body temperature. Furthermore, it addresses the drawbacks of existing ingestible sensors, which are typically too large, posing a swallowing difficulty and a risk of gastrointestinal obstruction. The new sensor integrates a sophisticated circuit onto a minuscule one-square-millimeter silicon chip. Its functionality relies on an oscillator designed around leakage current – the minimal electrical flow that occurs in a circuit when it is in an off state. The frequency of this oscillator is highly sensitive to the ambient temperature surrounding the chip, allowing for precise temperature detection. This system boasts an impressive accuracy of within 0.01 °C and is powered by a readily available 1.55-volt coin cell battery. To further enhance its energy efficiency and minimize the power requirements within the body, the researchers have implemented a technique known as backscattering. This method effectively outsources the majority of the power needs to an external antenna. The external antenna emits an ultra-high-frequency radio wave, which is then modulated by a corresponding antenna embedded within the ingestible sensor. This modulated signal is transmitted back to the external antenna. By meticulously interpreting the subtle changes within this radio wave, the external antenna can accurately calculate the internal temperature. Saransh Sharma, a former MIT postdoctoral researcher now affiliated with the University of Cambridge and the lead author of the research paper detailing this work, hailed the device as "the smallest ingestible capsule that we have seen for temperature-sensing paradigms." The research team envisions a broad spectrum of applications for this miniaturized sensor. These include continuous monitoring of infections, providing crucial data during and after anesthesia procedures, tracking fevers in children with greater precision, and assisting in the identification of ovulation cycles. Beyond clinical settings, the sensor could also prove invaluable for monitoring individuals exposed to extreme environmental conditions, such as athletes pushing their physical limits or soldiers operating in challenging terrains. Giovanni Traverso, an associate professor of mechanical engineering at MIT and one of the paper's senior authors, emphasized the sensor's potential for early infection detection, particularly for vulnerable patient groups, including those who are immunosuppressed. He expressed a long-term aspiration for this technology to eventually supersede existing methods of internal temperature monitoring. MIT Provost Anantha Chandrakasan is also a senior author on the paper. This development represents a significant stride in the field of miniaturized, continuous physiological monitoring, offering a less invasive, more accurate, and highly versatile alternative to current temperature-sensing practices.