A miniaturised ingestible CMOS-based sensor enables continuous internal temperature monitoring while consuming ultra-low power.
A pill-sized ingestible temperature sensor that allows for real-time internal monitoring with better than 0.1 degrees Celsius resolution. This device combines an ultra-low power integrated circuit and a wireless backscatter communication system and could be an alternative to traditional temperature-monitoring technologies for monitoring acute and chronic health conditions.
The ingestible sensor is six millimetres in diameter and four millimetres high, small enough to meet safety guidelines for orally administered devices. The core of the system is a custom 1 mm × 1 mm complementary metal-oxide semiconductor (CMOS) application-specific integrated circuit (ASIC) that converts temperature changes into detectable frequency changes using 10 nanowatts of power. The system is powered by a 4.8mm silver-oxide coin-cell battery. An on-chip regulator is used to ensure stable 1-volt supply with minimum energy consumption.
The device communicates wirelessly using a passive backscatter system with a custom 5 mm × 5 mm antenna tuned to 433 MHz. The sensor does not generate its own radio signal but modulates an external carrier wave to send out temperature data. The electronics are housed on a flexible printed circuit board and cased in a protective casing that can withstand the gastrointestinal environment.
Beyond ingestible applications, the miniature sensor was integrated into a one-millimetre catheter and used for continuous internal temperature monitoring without additional invasive probes. The device was also evaluated for vascular access guidance, where it detects temperature differences between blood vessels and surroundings.
Combining sensor miniaturisation, low power consumption, and wireless communication, the platform offers a practical approach for long-term physiological monitoring. Further development involves the minimisation of device size, enabling battery-free operation, and expanding the technology into a multimodal sensing system capable of monitoring parameters such as pH and pressure alongside temperature.
