The idea of making wearable sensors that adhere to the skin seems so easy and useful it’s surprising no one has developed them before. According to researchers, the major challenge in developing the technology was making the parts of the sensor as flexible and stretchy as skin. To do this, the researchers had to take brittle silicon and make it more bendable by making the sensor incredibly thin. The electronic parts of the sensor, light-emitting diodes, solar cells, transistors, and antennae, were assembled in an S-shape that would allow the circuits to still work when stretched in different directions.
The sensor components are stuck between two protective layers of the polymer polyimide, and these layers sit on top of a rubbery film of silicone that attaches to the skin using weak chemical bonds. The device adheres similarly to a temporary tattoo, which disguises the sensor grid and makes it stick longer. The electronic sensor is less intrusive than other electrode-based monitoring systems that require bulky wires.
According to the researchers, the devices can pick up heartbeats when stuck on the chest, skeletal muscle activity when on the leg, and brainwaves when on the forehead. In their trials of the device, the researchers recorded signals from a thin wire that relayed data to a computer. The sensors were able to collect accurate data for up to six hours and showed no sign of skin irritation where they were attached after 24 hours.
Nanoengineer Michael McAlpine of Princeton University (who was not involved in the research) told Science News:
“This is a huge breakthrough. This goes beyond Dick Tracy calling someone with a cell phone on the wrist. It’s having the wrist itself house the device so it’s always with you.”The potential for these devices goes far beyond just tracking heartbeats. The researchers tested their sensors to see if they could control a computer. When adhered to the throat, the device was able to read the electrical activity of the muscles moving when the test subject spoke the commands up, down, left, and right. This proved to be a successful way to control a computer’s cursor as it moved through a maze.
So far, the device can be powered by wireless coils and solar cells, and the researchers hope to improve the devices’ power storage capabilities. The researchers believe that in the future these devices could even run on the energy from body heat or stray electromagnetic signals.
Right now, the researchers are focused on the biomedical applications of this electronic sensor temporary tattoo, however, even with a multitude of medical possibilities, there are other ways this technology could be used. One example, aside from controlling computer movements, is CIA interest in developing the technology as a way for agents to silently communicate with one other by tracking the muscle movements that correspond with words.
While the technology isn’t available to the public, it is certainly an interesting breakthrough and it will be fascinating to see what kinds of new devices are spawned from it. The research was published in the journal Science.