MIT and Caltech Team Up on Ingestible Sensor That Pinpoints GI Issues

With surgical robots, wearables, and implantable technology like pacemakers, electronics contribute to healthier patients and longer lifespans than ever before. Now, a joint research team between MIT and Caltech has led to a new concept in medical technology: ingestible sensors. Specifically, the team developed a new way to track gastrointestinal (GI) issues via an ingestible magnetic sensor. 

 

The ingestible sensor. Image courtesy of MIT

 

In this article, we’ll take a look at traditional methods of tracking GI issues and how the new sensor is designed to improve them.

 

Current GI Tracking Methods

GI motility disorders are a group of conditions that affect the normal functioning of the digestive system. These disorders can affect any part of the digestive tract and can result in a slowdown or stop of food moving through the tract, resulting in nausea, abdominal pain, and a slew of other symptoms that can significantly impact a person's quality of life. It is estimated that around 35 million Americans are affected by GI motility disorders, making it an all-too-common health issue. 

Despite the prominence of GI motility disorders, diagnosing this problem remains particularly challenging. Currently, the standard convention is to diagnose these disorders through tests such as nuclear imaging studies, X-rays, or even catheters containing pressure transducers. These tests may help identify the location and severity of the motility disorder, but they each have their own unique shortcomings.

 

Nuclear and X-ray imaging are some main tools used to diagnose GI tract issues. Image courtesy of MDPI

 

One of the downsides of nuclear imaging studies and X-rays is that they involve exposure to ionizing radiation, which may be unsafe with repeated exposure. Additionally, these tests may not provide a complete picture of the patient's digestive system. For example, X-rays only show the structures of the digestive tract and may not show how well they are functioning. Nuclear imaging studies can show how well food is moving through the digestive tract, but they are less useful for identifying problems in specific areas of the digestive system.

Inserting catheters containing pressure transducers is unwelcome because it is a relatively invasive procedure that can be uncomfortable for patients. 

 

Ingestible Research

In search of a better way to diagnose these prevalent GI motility issues, researchers from MIT and Caltech teamed up to develop a new, ingestible sensor.

The resulting device was a single ingestible capsule that contained a magnetic sensor and a wireless transmitter. Once the patient swallows the capsule, the sensor works its way through the GI tract. Outside of the patient’s body, there is an electromagnetic coil that produces a magnetic field of known strength.

 

Some of the basic components of the ingestible sensor. Image courtesy of Nature

 

As the capsule moves through the patient’s GI tract, the system detects the strength of the received magnetic field from the external coil, from which it can determine its position within the GI tract. The wireless transmitter sends this information to a central beacon, where it can be collected and analyzed.

As described in the researchers' paper, a magnetic field gradient determines the spatial positions of the sensor and how long the sensor spends in each part of the GI tract. By knowing how much time the sensor spends in each part, the researchers can identify which parts of the GI tract are slower (or faster) than usual to determine how to treat a patient’s condition. 

In a large animal model, the researchers found that their ingestible sensor system was accurate within five to 10 millimeters of traditional X-ray approaches. Additionally, they found that their measurements were generally accurate to a resolution of about two millimeters—a number considered much higher than previously developed magnetic field-based sensors.