Microscopic size wireless sensors
A minuscule wireless sensor will be placed, in the body to track neural activity in real-time, to monitor people’s health from inside.
Berkeley researchers say the tiny neural implant can be placed in the brain, or monitor internal nerves, muscles or organs in real-time. The microscope device has been demonstrated successfully in rates and could be tested in people within two years.
How it Works
The sensors, which the researchers have already shrunk to a 1-millimeter cube — about the size of a large grain of sand — contain a piezoelectric crystal that converts ultrasound vibrations from outside the body into electricity to power a tiny, onboard transistor that is in contact with a nerve or muscle fiber.
A voltage spike in the fiber alters the circuit and the vibration of the crystal, which changes the echo detected by the ultrasound receiver, typically the same device that generates the vibrations.
The slight change, called backscatter, allows them to determine the voltage.
In an experiment last month, the UC Berkeley team powered up the passive sensors every 100 microseconds with six 540-nanosecond ultrasound pulses, which gave them a continual, real-time readout.
They coated the first-generation motes – 3 millimeters long, 1-millimeter-high and 4/5-millimeter-thick — with surgical-grade epoxy, but they are currently building motes from biocompatible thin films which would potentially last in the body without degradation for a decade or more.
The devices offer a potential new way to monitor or treat a range of conditions including epilepsy and control next-generation prosthetics.
Current medical technologies employ a variety of wired electrodes attached to different parts of the body to monitor and treat conditions ranging from heart arrhythmia to epilepsy. The Berkeley objective is to make those technologies wireless.
The new sensors have no need for wires or batteries. They use ultrasound waves both for power and to retrieve data from the nervous system.
The sensors, which the scientists called ‘motes,’ are about the size of a grain of sand.
The scientists used them to monitor in real time the rat peripheral nervous system — the part of the body’s nervous system that lies outside the brain and spinal cord.
The sensors are made up of components called piezoelectric crystals that convert ultrasound waves into electricity that powers tiny transistors in contact with nerve cells in the body.
The transistors record neural activity and, using the same ultrasound wave signal, send the data outside the body to a receiver.
The researchers said such wireless sensors potentially could give human amputees or quadriplegics a more efficient means of controlling future prosthetic devices.
Before implanting wireless sensors into the brain, the science of understanding how the brain processes and shares information need to advance further.
To deliver motes, currently one millimeter in size, into the brain, the researchers would need to miniaturize the sensors further to about 50 microns, about the width of a human hair.
‘It’s not impossible,’ Professor Maharbiz said. ‘The math is there.’
Associate Professor Michel Maharbiz, at the electrical engineering and computer science at the University of California, Berkeley. Dr. Eric Leuthardt, a professor of neurosurgery at Washington University in St. Louis.