MIT's Swallowable Sensor Could Replace Thermometers by Reading Your Temp from Inside
Taking your temperature sounds simple enough — stick a thermometer under your tongue, wait a few seconds, and done. But doctors have long known that surface readings like those can miss what is really happening deep inside the body, especially during serious illnesses or surgeries. A team of engineers and doctors at MIT has now built a sensor small enough to swallow, capable of measuring your core body temperature from inside your digestive tract every single second of the day, and it could change the way doctors monitor patients forever.
The sensor looks a bit like a tiny smooth berry — just four millimeters tall and six millimeters wide, which is smaller than most peas. That compact size matters a lot, because ingestible, meaning swallowable, temperature sensors already exist on the market, but most of them are about the size of a multivitamin capsule. At that size, some patients, especially children or people who are already unwell, have trouble swallowing them. There is also a small risk that a larger capsule could cause a blockage inside the digestive tract, the long winding system of organs that processes food from your stomach through your intestines. The MIT team's top priority was designing something so small that those risks basically disappear.
Getting the size down required some clever engineering tricks. The sensor has three core components: a temperature-sensing circuit built onto a silicon chip just one square millimeter in size, a miniature battery smaller than a fingernail, and a tiny internal antenna that sends data out of the body. To reduce how much power the circuit needed, the researchers designed it around something called leakage current — a tiny trickle of electricity that flows through a circuit even when it is switched off. Here is the interesting part: the temperature of the chip's surroundings changes the behavior of that leakage current, and the chip uses that change to calculate temperature with an accuracy of 0.01 degrees Celsius. That is far more precise than the thermometers most of us have at home.
The sensor saves even more power by using a communication method called backscattering. Think of it like a mirror reflecting light — instead of generating its own strong radio signal, the sensor's internal antenna reflects and slightly modifies a radio wave sent from a small device worn outside the body, usually within a foot or two. That outside device then reads the modifications to the reflected wave and calculates the exact temperature. Because the sensor is mostly just reflecting rather than broadcasting, it barely drains its tiny battery. The sensor sends a fresh temperature reading once per second, giving doctors a continuous, real-time stream of data.
The potential uses for this technology are wide-ranging. During surgery, patients are often put under anesthesia, which is medication that puts you into a deep sleep so you cannot feel pain. Anesthesia can interfere with the body's normal ability to regulate its own temperature, raising the risk of hypothermia, which is when the body gets dangerously cold. A swallowed sensor could alert medical teams to temperature changes the moment they start. Outside of hospitals, the sensor could help parents track a child's fever at home, assist athletes or soldiers operating in extreme heat or cold, and even help people monitor the subtle temperature shifts that signal ovulation when trying to start a family.
The researchers have already tested the sensor in pigs — first in a sedated animal during an anesthesia trial, and then in an awake, moving animal — and it accurately detected and transmitted temperature information in both situations. Now the team is working on expanding the sensor's abilities, aiming to combine the temperature reader with sensors for heart rate and other vital signs. They hope to begin human clinical trials, the carefully supervised medical tests required before any device can be used by the general public, within a few years. Giovanni Traverso, an engineering professor at MIT and a digestive system doctor at Brigham and Women's Hospital, put it plainly: he believes this tiny swallowable capsule could eventually replace all thermometers, because it gets closer to the body's true core temperature than anything worn on the skin ever could.
Source: Popular Science