Illustration of an ATOMS microchip localized within the gastrointestinal tract. The chip, which works on principles similar to those used in MRI machines, is embodied with the properties of nuclear spin. (Credit: Ella Marushchenko for Caltech)

A prototype miniature medical device could ultimately be used in “smart pills” to diagnose and treat diseases. A key to the new technology — and what makes it unique among other microscale medical devices — is that its location can be precisely identified within the body, something that proved challenging before.

Called ATOMS, which is short for addressable transmitters operated as magnetic spins, the new silicon-chip devices borrow from the principles of magnetic resonance imaging (MRI), in which the location of atoms in a patient’s body is determined using magnetic fields. The microdevices would also be located in the body using magnetic fields — but rather than relying on the body’s atoms, the chips contain a set of integrated sensors, resonators, and wireless transmission technology that would allow them to mimic the magnetic resonance properties of atoms.

The researchers say the devices are still preliminary but could one day serve as miniature robotic wardens of our bodies, monitoring a patient’s gastrointestinal tract, blood, or brain. The devices could measure factors that indicate the health of a patient — such as pH, temperature, pressure, sugar concentrations — and relay that information to doctors. Or, the devices could even be instructed to release drugs.

The final prototype chip, which was tested and proven to work in mice, has a surface area of 1.4 square millimeters. It contains a magnetic field sensor, integrated antennas, a wireless powering device, and a circuit that adjusts its radio frequency signal based on the magnetic field strength to wirelessly relay the chip’s location.