Engineers from MIT and Caltech have created an edible sensor that can be tracked in the digestive system. It helps doctors identify problems with digestion like constipation, acid reflux (GERD) and gastroparesis, so they know where digestion is slow.
The mini sensor inside the body can recognize a magnetic field made by an electromagnetic coil which is located outside of the body. The strength of this magnetic field will be different depending on how far away it is from the coil and that lets us calculate where the sensor is based on how strong it senses the magnetic field.
Scientists have found a way to put special sensors inside large animals that can track movement through their digestive system. This way, doctors will be able to diagnose certain stomach problems without having to do any painful procedures like the endoscopy.
Giovanni Traverso, a professor of mechanical engineering at MIT and a doctor at Brigham and Women’s Hospital, said that it is very important for people who suffer from GI dysmotility (a health problem with digestion) to be able to track their digestive system without having to go to the hospital.
Traverso and three other researchers, Azita Emami, Mikhail Shapiro, Saransh Sharma and Khalil Ramadi, wrote a new study that was recently published in the journal Nature Electronics. Azita and Mikhail are professors of electrical engineering and medical engineering at Caltech. Saransh is a graduate student at the same university, while Khalil had graduated from the Department of Mechanical Engineering and the Harvard-MIT Program in Health Sciences and Technology; he is now an assistant professor at New York University.
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About 35 million Americans suffer from GI motility disorders, which is when food has trouble moving through the digestive system. To diagnose this problem doctors use X-rays, special imaging studies or catheters (thin tubes) with pressure measuring devices that can detect how muscles in the digestive tract are contracting.
The MIT and Caltech researchers wanted to find a better way to diagnose what was causing digestion problems in patients. They created a pill that could be taken by the patient at home, which would then send out signals so doctors can know exactly where it is inside their digestive system. That way they can figure out why certain parts of their system may not be working properly and how to treat them.
The researchers took advantage of the fact that an electromagnetic coil’s field gets weaker in a specific way as you move away from it. They made a tiny magnetic sensor small enough to fit inside an ingestible pill. This sensor measures the surrounding magnetic field and uses this information to figure out its distance from the coil outside of your body.
Sharma explains that the magnetic field holds special information about locations, which allows us to design devices that can detect where they are just by measuring the magnetic field. We can then take this information to figure out the exact location of the device.
To figure out exactly where something is inside the body, scientists use two sensors. One of the sensors stays on the outside of the body and acts like a marker so that they know where the other sensor is inside. This outer sensor can be stuck to your skin and by finding out both positions at once, the researchers can find out where the inner sensor is in your digestive system.
The ingestible sensor comes with a transmitter that can send the data it records about magnetic forces to a computer or phone. Right now, it takes its measurements whenever it gets a signal from your phone, but you can also program it to take readings at set times.
Our system has the ability to help many devices at once while keeping their accuracy very high. It also covers a large area which is helpful for studying people and bigger animals, according to Emami.
This super cool sensor can pick up a magnetic field from certain coils, located near it, and these coils must be less than 60 centimeters away for the sensor to work. These coils could be inside someone’s backpack, clothing, or even behind a toilet! That way, the sensor can measure things whenever it is close enough to one of these special coils.
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The researchers did a test on a big animal with their new system. They put an edible capsule inside the stomach and checked where it travelled in the digestive system over some few days.
The researchers put two magnetic sensors together using a small rod. Then, they used the measurements from the magnetic field to figure out how far the two sensors were apart and were surprised to discover that the resolution was about 2 millimeters – much more accurate than regular magnetic-field-based sensors!
The scientists tested something called an ‘ingestible sensor’ (which goes inside your body) and a regular ‘sensor’ that gets attached to the outside of your skin. Then they measured how far away each of those sensors was from special coils, so they could tell when the ingestible one moved from the stomach all the way out until it was excreted. Lastly, they compared their results with X-rays and saw that both were accurate to within about 5 – 10 millimeters.
Using an external reference sensor helps to solve the problem that whenever a person or animal is near the coils, they won’t always be in exactly the same spot as before. It can be hard to know exactly where this pill is without X-rays or having something consistent as a reference that stays in the same place. According to Ramadi, this is how it works.
Medical experts say that this type of tracking can make it much simpler for doctors to determine the part of the digestive system that is causing digestion problems. Researchers note that “the ability to figure out how food moves through our bodies without needing radiation or devices inside us makes it easier for people to get evaluated.”
Researchers would like to work with people who can help them make the system that they have created, and then measure its results in animals. Finally, they hope to use it on humans too. If you’d like more information about this device, read the article “Smart Pills” Transform Diagnosis and Treatment of Gastrointestinal Disorders.
A group of scientists recently wrote a scientific paper called “Location-aware ingestible microdevices for wireless monitoring of gastrointestinal dynamics”. It explains how you can use tiny devices to keep track of things that happen in the stomach without having to connect any wires. This paper was published on 13th of February, 2023 and is available on the Nature Electronics website with a special code: 10.1038/s41928-023-00916-0.
This research was supported by the National Science Foundation, something called the Rothenberg Innovation Initiative, and the Heritage Medical Research Institute.
