Fabrication of Convex PDMS–Parylene Microstructures for Conformal Contact of Planar Micro-Electrode Array

Abstract

Polymer-based micro-electrode arrays (MEAs) are gaining attention as an essential technology to understand brain connectivity and function in the field of neuroscience. However, polymer based MEAs may have several challenges such as difficulty in performing the etching process, difficulty of micro-pattern generation through the photolithography process, weak metal adhesion due to low surface energy, and air pocket entrapment over the electrode site. In order to compensate for the challenges, this paper proposes a novel MEA fabrication process that is performed sequentially with (1) silicon mold preparation; (2) PDMS replica molding, and (3) metal patterning and parylene insulation. The MEA fabricated through this process possesses four arms with electrode sites on the convex microstructures protruding about 20 μm from the outermost layer surface. The validity of the convex microstructure implementation is demonstrated through theoretical background. The electrochemical impedance magnitude is 204.4 ± 68.1 kΩ at 1 kHz. The feasibility of the MEA with convex microstructures was confirmed by identifying the oscillation in the beta frequency band (13–30 Hz) in the electrocorticography signal of a rat olfactory bulb during respiration. These results suggest that the MEA with convex microstructures is promising for applying to various neural recording and stimulation studies.

Approaches of wearable and implantable biosensor towards of developing in precision medicine

“…(J) Schematic of a PDMS-parylene micro-electrode arrays (MEA) with 10 convex electrode sites in four arms for in vivo ECoG recording from rat olfactory bulb. Reprinted from reference ( 62 ), licensed under CC BY. (K) Photo of active area of a silicon carbide array that implanted on primary visual cortex of a rat for electrocorticography and peripheral nerve recording.…”

Applications of Electrospun Drug-Eluting Nanofibers in Wound Healing: Current and Future Perspectives

“…Solvent evaporation and solvent casting also involve the use of polymer while applying specific solvent removal techniques [ 93 ]. Hemispheres provide a means of developing reservoir-controlled drug release delivery methods; the production of the hemisphere involves coating core material with an insoluble polymer coating using conventional spray film coating techniques [ 99 ]. Micro-molding, hot embossing, and MRDL are techniques that are better suited for drug delivery to intact skin, considering that most are fabricated into microneedle arrays [ 93 ] and could therefore not be appropriate for application to open wounds.…”

The microbiota‐gut‐brain axis and epilepsy from a multidisciplinary perspective: Clinical evidence and technological solutions for improvement of in vitro preclinical models

“…Epileptic seizures were found to spontaneously arise from a specific area on hippocampal slices and many models recently tried to predict the complex spatiotemporal network propagation 159–161 . To follow such fine and complex signal distribution, some groups developed custom‐designed electrodes arrays with tissue‐conformal configurations, creating epilepsy‐specific high‐density MEAs that conform to the cytoarchitecture of the nervous tissue of interest 162,163 …”

“…[159][160][161] To follow such fine and complex signal distribution, some groups developed custom-designed electrodes arrays with tissue-conformal configurations, creating epilepsy-specific highdensity MEAs that conform to the cytoarchitecture of the nervous tissue of interest. 162,163 Electrographic screening, using the described approaches allowed us to achieve interesting findings in the identification of antiseizure medications, giving more information about the effects of different drugs on epileptogenesis 152 as well as about epileptic seizures dynamics both in vivo and in vitro. 164,165 In the last decade, big efforts have been made in developing MEA devices for recording the spiking activity of live neurons cultured in vitro, with the final aim of more reproducible live neuronal networks.…”