An MIT research team has developed an ingestible sensor that uses genetically engineered bacteria to detect and diagnose gastrointestinal problems.
The sensor is made up of a computer chip and bacteria that reacts to predefined biomarkers by luminescing. When it comes into contact with, say, markers associated with stomach bleeds, the bacteria glow. That light emission is picked up by the electronic chip, converted into a wireless signal, and transmitted to a smartphone application.
“By combining engineered biological sensors together with low-power wireless electronics, we can detect biological signals in the body and in near real-time, enabling new diagnostic capabilities for human health applications,” said Timothy Lu, an MIT associate professor of electrical engineering and computer science and of biological engineering.
Bacteria-on-a-chip
This ‘bacteria on a chip’ approach is another step forward in the sphere of synthetic biology. Engineering bacteria to respond to stimuli has been done before, but turning that technology into real-world applications is usually held back by the practicalities: sophisticated lab equipment is often required to measure the stimulus response, for example.
However, by combining sensors made from living cells with ultra-low-power electronics able to convert that response into a wireless signal, this latest MIT research represents a genuine breakthrough.
“Our idea was to package bacterial cells inside a device,” said lead author and former MIT postdoc, Phillip Nadeau. “The cells would be trapped and go along for the ride as the device passes through the stomach.”
The cylindrical sensor is about 1.5 inches long and needs just 13 microwatts of power to operate. The team thinks that, with further development, it could be shrunk to one-third of that size. So far, it’s proved able to detect the presence of blood in the stomachs of pigs.
The research team built in a 2.7-volt battery, which could provide enough power for the device for over a month of continuous use. In the future, it could also be sustained using a voltaic cell, harnessing stomach acid to power its operation, using technology that Nadeau and Anantha Chandrakasan, dean of MIT’s School of Engineering, have previously developed.
The team anticipates that this type of sensor could be used on a one-off basis or for continuous monitoring, sending updates from the digestive tract for weeks at a time.
Taking the hassle out of diagnosis
Patients with suspected gastric bleeding currently have to endure an endoscopy to confirm the problem. Often this requires sedation.
“The goal with this sensor is that you would be able to circumvent an unnecessary procedure by just ingesting the capsule, and within a relatively short period of time you would know whether or not there was a bleeding event,” said graduate student Mark Mimee.
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Perhaps the most exciting element of the study concerns the applications that go beyond gastrointestinal issues. The potential of ingestible sensors to provide doctors with the information they need appears to be limitless.
“Most of the work we did in the paper was related to blood, but conceivably you could engineer bacteria to sense anything and produce light in response to that,” said Mimee. “Anyone who is trying to engineer bacteria to sense a molecule related to disease could slot it into one of those wells, and it would be ready to go.