Temperature Sensor – A New Technology for Monitoring the Body from Within
Scientists have created a 6-millimeter device
The ingestible temperature sensor is just a few millimeters in size
How does the miniature thermometer work inside the body?
The sensor was tested in the stomach and intestine
Not just fever. The sensor can detect changes in blood flow
What could this technology change?
Scientists have created a device just 6 millimeters in size
An ingestible temperature sensor could in the future enable continuous monitoring of core body temperature without the need for conventional probes. Scientists at the Massachusetts Institute of Technology have developed a device measuring just 6 millimeters in diameter and 4 millimeters in height. The sensor transmits data wirelessly and can operate inside the gastrointestinal tract. For now, however, the technology has been tested exclusively in preclinical studies involving pigs.
Body temperature is one of the basic parameters used in medicine. The challenge arises when a single measurement is not enough and information is needed about how body temperature changes over time and how quickly it responds to specific events.
A measurement taken on the forehead, in the ear, or in the mouth does not always correspond to core body temperature. More accurate temperature-monitoring methods, meanwhile, may require probes that remain inside the body, cables, or more sophisticated equipment.
Researchers at MIT have proposed a different solution. Their ingestible temperature sensor is designed to operate inside the gastrointestinal tract and then wirelessly transmit temperature data. The findings were published on June 15, 2026, in the journal Nature Electronics.
The ingestible temperature sensor is just a few millimeters in size
The biggest challenge was not creating the thermometer itself. The problem was fitting it into a very small housing.
The system developed by the researchers, designated MITS, measures 6 millimeters in diameter and 4 millimeters in height. By comparison, earlier ingestible temperature sensors described in the publication were typically about 15–27 millimeters long and 7–11 millimeters in diameter. Their larger size was related, among other things, to power, electronics, and data-transmission requirements.
Miniaturization has practical significance here. The larger a sensor remains inside the gastrointestinal tract, the greater the potential difficulties with swallowing it and the risk of the device becoming lodged. The study authors used the dimensions of oral controlled-release drug-delivery systems as a reference, for which a limit of up to 15 millimeters in length and 9 millimeters in diameter was adopted. The new sensor is considerably smaller than these values.
The design resembles a small, smooth sphere. The researchers used a housing shape intended to facilitate the device’s movement through the gastrointestinal tract. The electronics were protected against the effects of the gastric and intestinal environment using materials designed for contact with the body.
Inside, there are three key components: the measurement circuit, the antenna, and the battery.
The smallest of these is the integrated circuit. It measures just 1 by 1 millimeter, yet it is responsible for measuring temperature. In addition, there is an antenna measuring approximately 5 by 5 millimeters and a silver-oxide battery measuring 4.8 millimeters in diameter and 1.6 millimeters in height.
It was the combination of these components that made it possible to create a complete sensor that can be placed inside the body.
How does the miniature thermometer work inside the body?
The heart of the device is a specially designed CMOS circuit. The researchers used the phenomenon of a small transistor leakage current. Its properties change with temperature, and this relationship makes it possible to convert temperature into an electrical signal that can then be read.
The solution has one very important advantage: it consumes extremely little energy.
The circuit requires about 10 nanowatts. This level of power consumption made it possible to use a very small battery. For comparison, the chip itself occupies an area of approximately one square millimeter.
Data transmission was another challenge.
A conventional radio transmitter would require additional power, which is simply not available in such a small device. Therefore, the researchers used backscatter technology, a communication method based on reflecting and modulating an external radio signal.
The sensor therefore does not need to generate a strong radio signal itself. An external antenna sends a wave at a frequency of 433 MHz. The miniature circuit inside the body changes the way this wave is reflected. These changes can then be received and converted into temperature information.
This solution makes it possible to reduce energy consumption while transmitting data without a wire extending from the body.
In tests, the researchers achieved transmission from a distance of approximately 50 centimeters. At the same time, they point out that the current external antenna is too large for a patient to wear comfortably. A much more practical antenna will therefore be needed in the future, for example in the form of a patch placed on the abdomen or a device worn on the chest.
The sensor was tested in the stomach and intestine
The researchers did not stop at laboratory tests. They tested the device in pig models because the physiology of the gastrointestinal tract and thermoregulation in pigs provides a useful model for preclinical research.
First, they checked whether the sensor could accurately measure temperature in different parts of the gastrointestinal tract. The device was placed endoscopically in the stomach, small intestine, and esophagus. The results were then compared with measurements obtained using an esophageal probe as a reference. The measurement error in these experiments was less than 0.1 degrees Celsius.
This is an important distinction. The electronic circuit itself has a resolution that allows it to detect very small changes in temperature, whereas the accuracy of the entire system after calibration was approximately 0.1 degrees Celsius. This does not mean that the device measures temperature to an accuracy of hundredths of a degree.
The researchers also had to calibrate each chip. This was necessary because of small differences between individual integrated circuits that can arise during manufacturing. The calibration used temperature points of 34, 37, and 40 degrees Celsius. After this process, the temperature-estimation error was less than 0.1 degrees.
The sensor was also tested under conditions that simulated the environment of the stomach and intestines. For 30 days, it remained in fluids simulating gastric and intestinal fluids. During this time, the device maintained stable operation and showed no problems related to moisture penetration.
That is considerably longer than the typical amount of time the sensor would be expected to spend in the gastrointestinal tract.
In another experiment, the device was tracked as it moved through a pig’s gastrointestinal tract. The sensor remained in the stomach for approximately three days, then entered the small intestine, and was excreted on the fifth day. After excretion, it was still functioning and could measure the temperature of its surroundings.
Importantly, the animal in this experiment was not kept immobilized throughout the study. The researchers observed the device under ambulatory conditions, while the animal moved normally in its environment. The authors did not observe any measurable deterioration in measurement quality associated with the device’s movement through the gastrointestinal tract.
This does not mean, however, that the sensor continuously recorded temperature in the pig for five days. Because of the size of the receiver used, the researchers collected data once a day for approximately 15 minutes. This is an important limitation of the current prototype.
Not just fever. The sensor can detect changes in blood flow
One of the most interesting elements of the experiment was the use of temperature to observe tissue ischemia.
When blood flow to a specific area is restricted, the temperature of that tissue can decrease. The researchers therefore investigated whether a very small sensor could detect such a change.
In a small-bowel ischemia model in pigs, blood flow in the vessels supplying a specific section of the intestine was blocked. The sensor was placed directly in that area. After ischemia was induced, the device recorded a temperature decrease of approximately 0.3 degrees Celsius. The temperature of the adjacent healthy section of intestine remained stable.
This demonstrates another possible role for miniature sensors. They do not have to be used solely to determine whether the body has a fever. In the future, similar systems could help monitor local temperature changes associated with blood flow.
The researchers also demonstrated that the same microscopic system could be used in medical devices other than an ingestible capsule.
The system, with an area of just 1 mm², was placed at the tip of a thin catheter. The sensor was then used in an intubation tube to monitor temperature. In another experiment, it was placed in a vascular catheter.
In the latter case, temperature helped identify the moment when the catheter tip entered a blood vessel. The researchers used the natural temperature difference between the vessel lumen and the surrounding tissues. As the catheter was advanced, the temperature increased, and after it entered the vein, it stabilized close to core body temperature. The experiment was performed in pigs, and ultrasound was still used to guide the procedure. The authors point out, however, that in the future, a similar temperature measurement could provide an additional method for confirming catheter placement.
This is where the miniaturization of the system opens up additional possibilities. The authors note that conventional temperature probes are larger in diameter and cannot always be inserted into very thin medical devices. Their system, by contrast, can be integrated into catheters with a much smaller cross-section.
What could this technology change?
There are several potential applications, but all of them should currently be regarded as directions for further research rather than ready-to-use clinical solutions.
One of them is monitoring patients at risk of infection. Continuous observation of core body temperature could be particularly interesting for people in whom rapid detection of changes is important, such as patients with compromised immune systems.
Another area is anesthesiology. Anesthesia can disrupt the body’s temperature-regulation mechanisms and increase the risk of hypothermia. In one experiment, MITS recorded a decrease in a pig’s core temperature from approximately 39 to 38.6 degrees Celsius within 15 minutes after the start of anesthesia.
The technology could also find applications in research on thermoregulation, sports, and monitoring people working in extreme temperatures. The researchers also mention the possibility of using changes in core temperature to monitor fertility.
At the same time, the current prototype has clear limitations.
First and foremost, human trials have not yet been conducted. All of the described in vivo experiments were performed on pigs. The authors emphasize the need for further studies that take into account anatomical differences, different gastrointestinal transit conditions, and comorbidities in humans.
The external receiver also remains an issue. The current system requires a relatively large antenna. For the device to operate in everyday human conditions, a receiver that can be worn by the patient will be needed. The researchers point to solutions such as an abdominal patch or a smart vest.
Another challenge will be combining temperature measurements with other parameters. The authors anticipate the possibility of adding sensors in the future to measure pH, pressure, or biomarkers, among other things. Such an expansion would, however, increase energy requirements and take up more space. Miniaturization will therefore remain one of the key engineering challenges.
The direction of future power development is also interesting. The authors point out that, with the right technology, future versions of such devices could potentially harvest energy directly from the body, eliminating the need for a battery. This, however, remains a concept for further development rather than a feature of the current prototype.
The key point, therefore, is that the researchers have not yet created an “intelligent capsule” that would replace a thermometer and be available in pharmacies. Instead, they have created a very small measurement platform demonstrating that sophisticated electronics can operate inside the body while consuming power measured in nanowatts.
If further studies confirm the safety and effectiveness of the solution in humans, the ingestible temperature sensor could become part of a new generation of medical devices. Their common feature would be not only miniaturization, but also the ability to observe processes occurring inside the body over an extended period without the need to perform repeated individual measurements.
This is the direction in which the technology is heading: from a thermometer that has to be placed against the body to a small sensor that can collect information from inside the body and transmit it externally.
For now, however, this remains a preclinical technology. The path from animal studies to routine use in patients will require clinical trials, further miniaturization of the receiver, safety assessments, and testing of the device in different patient populations.
Bibliography
- Sharma S., Cai Y., Moon I. et al., A miniaturized ingestible temperature sensor for continuous internal monitoring, Nature Electronics, vol. 9, pp. 956–968, 2026. Published June 15, 2026.
- Trafton A., A tiny ingestible sensor can measure temperature from inside the body, MIT News, June 15, 2026.
