Ultra‐Low Cost, Facile Fabrication of Transparent Neural Electrode Array for Electrocorticography with Photoelectric Artifact‐Free Optogenetics

Abstract

Transparent implantable devices have received significant attention in neuroscience and biomedical engineering by combining neural recording and optical modalities. Opaque, metal‐based electrode arrays for electrophysiology block optical imaging and cause photoelectric artifacts, making them difficult to integrate with optogenetics. Here, a photoelectric artifact‐free, highly conductive, and transparent poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) electrode array is introduced as promising neural implants. The technology which is developed in this work provides transparent neural interfaces through low‐cost, ultra‐facile method compared with other transparent materials being applied to implantable tools. The device exhibits superior optical, mechanical, and electrical characteristics to other studies, thanks to a simple ethylene glycol immersing process. The device performance is highlighted by comparing its light stimulation efficiency and photoelectric artifact extent with conventional thin gold electrodes both in vitro and in vivo. This platform can assemble transparent neural interfaces much more efficiently than any other material candidates and thus has many potential applications.

E-Cannula reveals anatomical diversity in sharp-wave ripples as a driver for the recruitment of distinct hippocampal assemblies

“…Besides graphene, other transparent electrode materials have been proposed in the literature ( Kwon et al, 2013 ; Cho et al, 2022 ; Neto et al, 2021 ; Qiang et al, 2018 ; Liu et al, 2021 ). Indium tin oxide (ITO) has also been used for transparent microelectrode arrays ( Kwon et al, 2013 ).…”

“…However, compared with graphene, it is more brittle and susceptible to cracking and other mechanical degradations. PEDOT-PSS has been recently adopted to fabricate transparent electrodes ( Cho et al, 2022 ), but this material system suffers from poor chronic reliability due to delamination issues. Silver nanowires ( Neto et al, 2021 ) or gold meshes ( Qiang et al, 2018 ) have been used to fabricate transparent electrodes, but these metals still absorb the light leading to light-induced artifacts.…”

In Vivo Penetrating Microelectrodes for Brain Electrophysiology

“…For example, the use of carbon fibers causes a lower immune response after implantation in the CNS compared to metal microelectrodes [ 72 , 73 , 74 ]. In addition, recently, conductive polymers [ 75 , 76 , 77 ] have been used as nontoxic materials, typical examples of which are poly-3,4-ethylenedioxythiophene (PEDOT) and its modifications [ 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 ], polypyrrole (PPy) [ 89 , 90 , 91 , 92 ] and polyaniline (PANi) [ 93 , 94 , 95 ].…”

Vitamin C-Induced Enhanced Performance of PEDOT:PSS Thin Films for Eco-Friendly Transient Thermoelectrics

“…In this respect, conductive organic polymers have recently garnered attention as next-generation TE materials due to their intrinsically lower lattice thermal conductivity compared to their inorganic counterparts. − Specifically, poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS) has been intensively investigated owing to its high electrical conductivity, , solution processability, , and easy tunability of its redox state (i.e., bipolaron to neutral) that facilitates the optimization of σ and S . − Furthermore, due to its low toxicity and superior biocompatibility, , PEDOT:PSS-based organic thermoelectric (OTE) devices are potentially applicable for biodegradable and transient electronics. , Nevertheless, the doping and dedoping processes for optimizing the PF generally entail intricate steps, such as blending additives, sequential treatments, and thermal annealing, which resultingly cause inevitable sacrifice of either σ or S due to concomitant morphology change. − Additionally, synthetic chemicals or highly hazardous additives (e.g., H 2 SO 4 ) that are eco-unfriendly have been commonly involved in the optimization processes, , which may cause environmental issues during fabrication. Hence, to meet the criteria of green electronics, OTE needs novel strategies from fabrication to disposal of the devices for being a genuinely green energy source.…”