In the treatment of epilepsy and other neurological disorders, doctors sometimes implant arrays of stimulating electrodes on the surface of patients’ brains. A new soft robotic system makes the placement of these electrodes much less invasive than ever before.
The problem with implanting an entire set of connected electrodes is that a considerable portion of the skull must be removed (and then replaced) in the process. Needless to say, if a small hole is enough, all the better.
With this challenge in mind, scientists at the EPFL Institute in Switzerland have designed an “inflatable” electrode array made of a soft, biocompatible elastomer with six helical arms that resemble twisted Unfold like petals. There are multiple gold electrodes on the bottom of each arm.
Initially, the deflated device folded inside out inside a cylindrical tube. The end of the tube is then inserted through a 2 cm (0.8 in) wide hole in the skull into the 1 mm space between the brain and the skull. A harmless fluid is then pumped into the array, causing each arm to inflate in turn and gently pop into shape inside the skull.
When the process was complete, the flower-shaped array covered a 4-centimeter (1.6-inch) wide area of the cerebral cortex, even though the hole it passed through was only half that size. Because the arms of the array turn outward from the right side as they inflate, the electrodes on their undersides make full contact with the brain tissue.
The technology has been successfully tested in minipigs and is currently being commercialized by EPFL spin-off company Neurosoft Bioelectronics. With further development of this device, the size of the hole in the skull and the deployed electrode array may decrease and increase, respectively.
A paper on the research led by Professor Stéphanie Lacour and robotics researcher Sukho Song was recently published in the journal scientific robot. The system is demonstrated in the video below.
Deployable electrodes for minimally invasive brain surgery