Flexible Microelectrode Array for Chronic Electrocorticography Recording under Different Neurophysiological Conditions

Abstract

Electrocorticography signal acquisition using implanted flexible microelectrode arrays is a popular approach for neural status monitoring. This interdisciplinary research shows the design, fabrication, characterization, and validation of a 10-channel flexible microelectrode array for chronic electrocorticography acquisition from a rat. The array was fabricated using titanium/gold electrodes, flexible biocompatible polyimide as substrate as well as insulation layers. The fabricated array facilitated subdural recording from the cortical surface of a rat. The reliability of the developed electrode array, subsequent acquisition module, and preprocessing approach was checked for an epilepsy model in rodents. Peripheral electrical stimulation was used to elicit epilepsy, minimizing tissue damage. The implanted array faithfully recorded baselines, epileptic activities induced by peripheral electrical stimulation at the forepaw, recovered baselines upon antiepileptic drug administration, and the somatosensory evoked potentials by touching whiskers in a chronic study. The preprocessed traces from the awake and sedated rats ensured the utilization potential of this array for chronic signal acquisition. Subsequently, the time-frequency analysis of the extracted signals shows a significant contrast in temporal features among the neurophysiological conditions. The OpenBCI Cyton Boards were used in these studies to acquire brain signals. Histology of the formalin-fixed rat brain showed no significant damage due to implantation.