Ingestible Sensor Uses Genetically Engineered Bacteria To Diagnose

Researchers at MIT have developed an ingestible sensor equipped with genetically engineered bacteria, that can diagnose bleeding in the stomach or other gastrointestinal problems. Called a “bacteria-on-a-chip”, the technology combines sensors made from living cells with ultra-low-power electronics that convert the bacterial response into a wireless signal that can be read by a smartphone.

“By combining engineered biological sensors together with low-power wireless electronics, we can detect biological signals in the body in near real-time, enabling new diagnostic capabilities for human health applications,” said Timothy Lu, an associate professor at MIT.

The sensor, a cylinder about 1.5 inches (~ 4 cm.) long, requires about 13 microwatts of power. It is equipped with a 2.7-volt battery, which is estimated to power the device for about 1.5 months of continuous use. The ingestible sensor has been tested in pigs and has shown that it could correctly determine whether any blood was present in the stomach. It is anticipated that this type of sensor could be either deployed for one-time use or designed to remain in the digestive tract for several days or weeks, sending continuous signals.

The team used Lactococcus lactis, a microbe used to curdle milk into cheese. The microbe functions at its best in the presence of heme – the iron-containing molecule that transports oxygen in the blood. As taking up too much heme can be toxic, the microbes have a system to sense how much there is, complete with genetic switches to change their metabolism. Lu’s team took L. lactis’s on-switch DNA, coupled it with genetic code for bacterial bioluminescence, and inserted the mix inside a strain of E. coli commonly sold as a probiotic. Those modified cells went into a body-safe capsule equipped with a semipermeable membrane on one side to let in liquid from the gut and the power system.

The report “An ingestible bacterial-electronic system to monitor gastrointestinal health” has been published in ‘Science’.