Gut disorders are uniquely difficult for doctors to diagnose without turning to invasive procedures. To alleviate this issue, electronic pills that can snap photos or track temperature, pH, or gases have emerged. A multidisciplinary team of researchers at Massachusetts Institute of Technology has now debuted a biosensing capsule that goes beyond general measurement or mapping and can detect specific molecules (Science 2018, DOI: 10.1126/science.aas9315). The ingestible microbioelectronic device (IMBED) uses bioluminescent bacteria engineered to light up in the presence of heme molecules, which would be helpful for diagnosing gastrointestinal bleeding. Powered by a small button battery, a luminescence chip detects the emitted light and a microprocessor converts the light to an electrical signal. An antenna transmits the signal to a smartphone or laptop waiting to receive the data. After administering the pill to pigs given a solution of blood as well as pigs that weren’t, the researchers confirmed that the capsule could correctly detect blood inside the swines’ guts. The next goal is to shrink the capsule, which the authors say an individual could swallow at its current size if they were very motivated, by combining the separate chips onto a single integrated circuit.