Researchers have built an ingestible sensor equipped with genetically engineered bacteria that can diagnose bleeding in the stomach or other gastrointestinal problems.

Bacteria engineered to detect specific molecules are placed in four wells on the custom-designed sensor. (Credit: Melanie Gonick/MIT)

This “bacteria-on-a-chip” approach 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. The researchers created sensors that respond to heme, a component of blood, and showed that they work in pigs. They also designed sensors that can respond to a molecule that is a marker of inflammation.

The sensor, which is a cylinder about 1.5 in. long, requires about 13 μW of power. The researchers equipped the sensor with a 2.7-V battery, which they estimate could power the device for about 1.5 months of continuous use. They say it could also be powered by a voltaic cell sustained by acidic fluids in the stomach.

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