We could be in for a Fantastic Voyage-style future where tiny medical devices swim through our bodies to deliver drugs or diagnose diseases, but keeping track of all those little explorers can be tricky. A new invention out of Caltech might help make that easier. It's a chip loaded with sensors that can ping its location in the body, thanks to MRI-inspired technology.

It can be hard to check the inner goings-on of a patient's body without being too invasive, but "smart pills" could provide an easy-to-swallow alternative. So far, these diagnostic devices include the likes of a sensor to measure gas concentrations in the intestine, and a tiny camera to snap images where colonoscopies can't reach. The new Caltech device could eventually be part of these systems, allowing doctors to monitor the pill's progress through the patient.

"The dream is that we will have microscale devices that are roaming our bodies and either diagnosing problems or fixing things," says Azita Emami, co-lead researcher on the study. "Before now, one of the challenges was that it was hard to tell where they are in the body."

To solve that problem, the team developed a device called addressable transmitters operated as magnetic spins (ATOMS). The prototype measures 1.4 sq mm, about 250 times smaller than a penny, and packed into that tiny space is a magnetic field sensor, integrated antennas, a wireless power source and a location circuit that responds to the changing magnetic field around it to beam out the chip's location in the body.

The ATOMS chip is 250 times smaller than a penny, as seen here Shapiro and Emami Labs/Caltech

"A key principle of MRI is that a magnetic field gradient causes atoms at two different locations to resonate at two different frequencies, making it easy to tell where they are," says Mikhail Shapiro, co-lead researcher on the project. "We wanted to embody this elegant principle in a compact integrated circuit. The ATOMS devices also resonate at different frequencies depending on where they are in a magnetic field."

According to the team, it was a challenge to balance the ATOMS prototype's small size, low power consumption and location-pinging accuracy, but in the end, it proved effective in tests in mice.

This early version of the device was mostly a tech demo for the tracking system, but in the long run the chips could be built into other microscale devices patrolling the body for cancer or clogged arteries.

"You could have dozens of microscale devices traveling around the body taking measurements or intervening in disease," says Shapiro. "These devices can all be identical, but the ATOMS devices would allow you to know where they all are and talk to all of them at once."

The study was published in the journal nature Biomedical Engineering.

Source: Caltech