ABSTRACT: Brain/machine interfaces will play a significant role in the coming decades. As a means to enhance human abilities they are set to fundamentally change the course of humanity. Today, there is no clear winner in the race towards a practical in-vivo interface. We present here the latest work completed at UNSW using multi-optrode arrays, a technology based on ferroelectric liquid crystals that has the potential to deliver 1 million neuronal connections: a stated goal of the DARPA program.

ABSTRACT: We propose an optical electrode ’optrode’ sensor array for biopotential measurements. The transduction mechanism is based on deformed helix ferroelectric liquid crystals which realign, altering the optrode’s light reflectance properties, relative to applied potential fields of biological cells and tissue..... 

ABSTRACT: Brain/computer interfaces (BCIs) rely on the concurrent recording of many channels of electrical activity from excitable tissue. Traditionally such neural interfacing has been performed using cumbersome, channel-limited multielectrode arrays. We believe that BCIs can greatly benefit from using an optical approach based on simple yet powerful liquid-crystal based transducer technology. This approach potentially offers a technology platform that can sustain the necessary bandwidth, density of channels, responsivity, and conformability that are required for the long-term viability of such interfaces....

ABSTRACT: Liquid crystals (LCs) are recognised as an emerging type of responsive and functional materials that exhibit diverse technological applications. The spatial arrangement or alignment of LC molecules creates an optical anisotropy, which influences the propagation of light. This study presents an automated image processing algorithm designed to quantitatively assess LC alignment. The algorithm calculates the image structure tensor and computes a score ranging from 0 to 1 to represent the uniformity of LC alignment.....

ABSTRACT: Recording and monitoring electrically-excitable cells is critical to understanding the complex cellular networking within organs as well as the processes underlying many electro-physiological pathologies. Biopotential recording using an optical-electrode (optrode) is a novel approach which has potential to significantly improve interface-instrumentation impedance mismatching as recording contact-sizes become smaller and smaller. Optrodes incorporate a conductive interface that can sense extracellular potential and an underlying layer of liquid crystals that passively transduces electrical signals into measurable optical signals......

ABSTRACT: The design of a bi-directional optical-electrode or ’optrode' for peripheral nerve and brain-machine interfacing is proposed and its principle of operation detailed, which is able to provide biphasic stimulus and charge balancing functionalities. The prototype chip is fabricated, characterised on the bench, and assessed in vivo and ex vivo. Results show that it can simultaneously stimulate and record from the rabbit sciatic nerve, and entrainment of the sino-atrial node is achieved and observed by the prototype.......

ABSTRACT: Biomedical instrumentation and clinical systems for electrophysiology rely on electrodes and wires for sensing and transmission of bioelectric signals. However, this electronic approach constrains bandwidth, signal conditioning circuit designs, and the number of channels in invasive or miniature devices. This paper demonstrates an alternative approach using light to sense and transmit the electrophysiological signals........