Stanford engineers have invented a wireless pressure sensor that has already been used to measure brain pressure in lab mice with brain injuries. The underlying technology has such broad potential that it could one day be used to create skin-like materials that can sense pressure, leading to prosthetic devices with the electronic equivalent of a sense of touch. In one simple demonstration they used this wireless pressure sensor to read a team member’s pulse without touching him.
The wireless sensor is made by placing a thin layer of specially designed rubber between two strips of copper, which act like radio antennas. The rubber serves as an insulator. The technology involves beaming radio waves at this simple antenna-and-rubber sandwich. When the device comes under pressure, the copper antennas squeeze the rubber insulator and move infinitesimally closer together. That tiny change in proximity alters the electrical characteristics of the device. Radio waves reflected by these antennas slow down in terms of frequency. When pressure is relaxed, the copper antennas move apart and the radio waves accelerate in frequency.
In a separate effort, the device was used to take a wireless pulse reading as a proof of principle that the technology could be applied to pressures having to do with blood circulation.