Iran – Researchers at Khajeh Nasir Toosi University of Technology (KNTU), Tehran, Iran, have designed, developed, and tested a micro-electrocorticography (μECoG) system. Electrocorticography is a minimally invasive approach for electrical recording of extracellular neuronal activities from the surface of the brain.
This approach is of higher temporal and spatial resolution than electroencephalography (EEG), and less invasive than intra-cortical neural recording. The ECoG approach for neural recording is nowadays of interest in a variety of application areas such as brain-machine interfacing (BMI) and brain mapping.
Researchers in Dr Amir M Sodagar’s Research Laboratory for Integrated Circuits and Systems (ICAS) at KNTU have declared the development of their third-generation μECoG system. This is a battery-powered system, capable of recording neuronal activities from the surface of the brain on eight individual channels in parallel. All the eight channels being recorded are concurrently transmitted to an external host through wireless connection in the real time.
The system consists of two modules: a semi-implantable recording unit and an external host. The recording unit comprises a microelectrode array (MEA), electronic circuitry, rechargeable small batteries, and a radio-frequency (RF) transmitter for data telemetry. The external host consists of an RF receiver, a protocol converter and computer interfacing block, and a software unit dedicated to post-processing and graphical interfacing to the user.
For this system, the MEA was fabricated on a bio-compatible substrate using a combination of three-dimensional (3D) printing and micro-drilling technologies. Electronics of the recording unit were implemented on multiple printed-circuit boards (PCBs). The PCBs, the batteries, and the MEA are all stacked on top of each other in a fairly small physical size (2.5cm x 2.5cm x 2.2cm) inside a compact bi-cubical 3D-printed biocompatible package.
The system has successfully passed functional tests with pre-recorded neural signals at KNTU, as well as in-vivo electrophysiological experiments for the signal-sensitive parts such as the MEA and analog electronics circuits in Professor Mirnajafizadeh’s Seizure Laboratory at Tarbiat Modares University, Tehran, Iran. This project received a special grant from KNTU and was also financially supported by the Iranian Cognitive Sciences and Technologies Council (CSTC).