First Biopotential Recordings from a Liquid Crystal Optrode

One of the goals of the Neural Engineering System Design (NESD) program in the United States and of similar programs around the world is to develop an interface able to read from one million neurons in parallel. This is well beyond the capabilities of traditional multi-electrode arrays (MEAs), which are inherently limited in both spatial resolution and number of channels, due to issues with power dissipation and wiring.(1,2) To overcome these roadblocks our group has proposed a novel optrode array that measures electrical activity and uses light for both signal transduction and transmission, thus decoupling the bio-potentials from the signal acquisition circuitry.(3) The technology relies on the sensitivity of a particular class of liquid crystals (LCs) to small electric fields and is analogous to a LC display, where the intensity of each pixel (optrode, in our case) is controlled by the electrical activity of the biological tissue. Here, we present the first use of such a transduction mechanism to record from cardiac tissue and investigate stimulus artifact suppression in rabbit sciatic nerve. Our results pave the way to the development of high-density high-channel-count optrode arrays for electrophysiology studies and brain-machine interfaces.