State‐of‐the‐Art Electronic Materials for Thin Films in Bioelectronics

Abstract

This review is dedicated to electronics materials enabling thin‐film‐based neural interface and bioelectronics devices. First‐generation bioelectronic medicine devices feature hand‐crafted bulk interface electrodes, wires and interconnects, and insulators. This review discusses how modern materials science, especially know‐how repurposed from semiconductor and microdevice technologies, enables next‐generation bioelectronics. Those are divided into two subgroups: second and third generation. The former refers to rigid microscaled devices, while the latter is defined as soft, ultrathin, and flexible microdevices. A critical assessment of different biointerface electrodes, conductors for interconnects, and insulators for substrates, passivation, and encapsulation layers is made. The goal is not to give an exhaustive account of every use‐example of given materials, but to point out specific aspects that are relevant to making the right choices for materials for a given device or application. Unique advantages of specific materials are highlighted, while also focusing on weaker points and caveats that those materials may have. The goal is to have an up‐to‐date handbook for persons entering the field which also points out tips and tricks as well as challenging problems that researchers can be inspired to confront and overcome.

Flexible high-density microelectrode arrays for closed-loop brain–machine interfaces: a review

“…As a result, they are better equipped to tackle challenges in the mechanical, electrical, chemical, or biological domains. Some reviews by Gablech and Glowacki (2023) and Tringides and Mooney (2022) have been discussed about the material advances in MEAs development, thus we will just give an overview in this part.…”

Unveiling Trends: Nanoscale Materials Shaping Emerging Biomedical Applications

“…Bioelectronic materials are used to make functional connections between electronic devices and the human body. − These materials allow the use of high precision, sensitive electronics to sense biological processes, or to send electrical signals to tissues or cells. Bioelectronic devices are typically implanted or attached to the skin.…”

Monitoring the Electrochemical Failure of Indium Tin Oxide Electrodes via Operando Ellipsometry Complemented by Electron Microscopy and Spectroscopy

“…In Figure , our operando setup is sketched. We have chosen an aqueous physiological electrolyte having a neutral pH to relate to potential bioelectronic applications, such as electrochemical biosensors, photobioelectrodes to study natural and artificial photosystems or for biophotovoltaic or bioelectrocatalytic purposes, and ultimately bioelectronic medical interfaces, more specifically photocapacitors for stimulation of neuronal cells. ,,,− For the latter, ITO is rather used as an additional coating layer for ultrathin gold electrodes to prevent anodic chloride-mediated corrosion and cathodic electrolytic activity even in physiological electrolytes, as well as to serve as an adhesion layer for biopolymers and cells without sacrificing transparency . All applications rely on both the conductivity and the full spectral transparency of ITO electrodes to allow for steady transmission of probing or stimulating light beams.…”

“… 4 , 6 , 7 , 70 − 79 For the latter, ITO is rather used as an additional coating layer for ultrathin gold electrodes to prevent anodic chloride-mediated corrosion and cathodic electrolytic activity even in physiological electrolytes, as well as to serve as an adhesion layer for biopolymers and cells without sacrificing transparency. 79 All applications rely on both the conductivity and the full spectral transparency of ITO electrodes to allow for steady transmission of probing or stimulating light beams. To avoid that, for instance, incipient darkening of the ITO electrode is mixed up with the signal from an analyte of a biosensor, precise awareness of the ITO’s passive operational electrochemical potential window for a specific electrolyte environment is crucial.…”