Ghajar, M. H. | Search bioRxiv

bioRxiv2024

A low-cost protocol for reconditioning of deep-brain neural microelectrodes with material failure for electrophysiology recording

Up to now, a large variety of neural microelectrodes are developed. Although there are a lot of published works in this area, the majority of them are about the fabrication methods and rarely discuss the reconditioning procedure or how to re-use the electrodes that their performance is decreased because of material failure. In this paper, firstly, it is answered that why the performance of neural microelectrodes decreases. Secondly, a general low-cost protocol for reconditioning and re-using electrodes are proposed that can be utilized for the most types of electrodes with material failure. Lastly, the proposed reconditioning protocol is applied experimentally to single-site tungsten microelectrodes to demonstrate the effectiveness of the protocol. Neural signal recording Results clearly indicate that a large number of electrodes can be reconditioned well.

bioengineering↗

bioRxiv2021

Sensing Local Field Potentials with a Directional and Scalable Depth Array: DISC

A variety of electrophysiology tools are available to the neurosurgeon for diagnosis, functional therapy, and neural prosthetics. However, no tool can currently address these three critical needs: (i) access to all cortical regions in a minimally invasive manner; (ii) recordings with microscale, mesoscale, and macroscale resolutions simultaneously; and (iii) access to spatially distant multiple brain regions that constitute distributed cognitive networks. We present a novel device for recording local field potentials (LFPs) with the form factor of a stereo-electroencephalographic electrode but combined with radially positioned microelectrodes and using the lead body to shield LFP sources, enabling directional sensitivity and scalability, referred to as the DISC array. As predicted by our electro-quasistatic models, DISC demonstrated significantly improved signal-to-noise ratio, directional sensitivity, and decoding accuracy from rat barrel cortex recordings during whisker stimulation. Critically, DISC demonstrated equivalent fidelity to conventional electrodes at the macroscale and uniquely, revealed stereoscopic information about current source density. Directional sensitivity of LFPs may significantly improve brain-computer interfaces and many diagnostic procedures, including epilepsy foci detection and deep brain targeting.

bioengineering↗