Researchers at the University of California Berkeley have created a tiny sensor, the size of a grain of sand, that can sit on a nerve, muscle, or organ and monitor the electrical signals passing through it. The sensor, dubbed "neuro dust", was designed as a next-generation control interface for prostheses but could eventually turn out to have a wide range of healthcare applications. 

“I think the long-term prospects for neural dust are not only within nerves and the brain, but much broader," Michel Maharbiz, an associate professor of electrical engineering and computer sciences at UCB, said in a statement. “Having access to in-body telemetry has never been possible because there has been no way to put something supertiny superdeep. But now I can take a speck of nothing and park it next to a nerve or organ, your GI tract or a muscle, and read out the data."

Maharbiz was one of the main authors on a study of the technology that recently appeared in the journal Neuron. In the study, they successfully implanted the sensors onto the neurons of rats. The sensor communicates with a receiver outside the body using ultrasound, which removes any concerns about harmful radiation that might arise from a radio or cellular transmitter.

The first-generation device is three millimeters long, one millimeter high and four-fifths of a millimeter thick. But researchers hope to scale the device down to about 50 microns, or 0.05 millimeters. That's the size that would be required to implant into the brain so quadroplegics could control a prosthetic. But even at the current size, the device is small enough to be used in the peripheral nervous system.

Current implantable electrodes degrade within a few years and have to be replaced, but this tiny sensor could be sealed in to avoid infection and could potentially last a lifetime.

Future applications could include bladder control, appetite supression, or treatment of epilepsy or inflammation. Researchers also have high hopes that they can reconfigure the sensor to detect not only electrical signals, but also oxygenation and hormone levels.

“The vision is to implant these neural dust motes anywhere in the body, and have a patch over the implanted site send ultrasonic waves to wake up and receive necessary information from the motes for the desired therapy you want,” said Dongjin Seo, a graduate student in electrical engineering and computer sciences, said in a statement. “Eventually you would use multiple implants and one patch that would ping each implant individually, or all simultaneously.”