High‐Density Stretchable Electrode Grids for Chronic Neural Recording

Abstract

Electrical interfacing with neural tissue is key to advancing diagnosis and therapies for neurological disorders, as well as providing detailed information about neural signals. A challenge for creating long-term stable interfaces between electronics and neural tissue is the huge mechanical mismatch between the systems. So far, materials and fabrication processes have restricted the development of soft electrode grids able to combine high performance, long-term stability, and high electrode density, aspects all essential for neural interfacing. Here, this challenge is addressed by developing a soft, high-density, stretchable electrode grid based on an inert, high-performance composite material comprising gold-coated titanium dioxide nanowires embedded in a silicone matrix. The developed grid can resolve high spatiotemporal neural signals from the surface of the cortex in freely moving rats with stable neural recording quality and preserved electrode signal coherence during 3 months of implantation. Due to its flexible and stretchable nature, it is possible to minimize the size of the craniotomy required for placement, further reducing the level of invasiveness. The material and device technology presented herein have potential for a wide range of emerging biomedical applications.

A Wearable Second Skin‐Like Multifunctional Supercapacitor with Vertical Gold Nanowires and Electrochromic Polyaniline

“…[17][18][19][20][21][22] Some supercapacitors have also been successfully combined with other energy harvesters to actualize wearable integration systems. [25][26][27][28][29] Despite the encouraging progresses made in flexibility, stretchability, as well as impressive electrochemical performances based on multiple material and design combinations, very limited supercapacitors have actually enabled wearable on-skin applications. [25][26][27][28][29] Despite the encouraging progresses made in flexibility, stretchability, as well as impressive electrochemical performances based on multiple material and design combinations, very limited supercapacitors have actually enabled wearable on-skin applications.…”

Bioinspired Prosthetic Interfaces

“…The number of electrodes and stretchability can be adjusted depending on the brain area of interest. Figure a–c shows some of these examples: a 4‐electrode sinusoidal stretchable gold nanobelts on PDMS and a 32‐electrode grid made of Au‐TiO 2 NW conductors embedded in PDMS . Nanostructuring of individual electrodes can lower the impedance while maximizing the electrode area for signal capture such as Au/PEDOT:PSS bilayer‐nanomesh …”

“…Figure 16a-c www.advmattechnol.de shows some of these examples: a 4-electrode sinusoidal stretchable gold nanobelts on PDMS [245] and a 32-electrode grid made of Au-TiO 2 NW conductors embedded in PDMS. [246] Nanostructuring of individual electrodes can lower the impedance while maximizing the electrode area for signal capture such as Au/ PEDOT:PSS bilayer-nanomesh. [220] In order to achieve much higher quality with a lower signalto-noise ratio recording, a neural device needs to be as close to or directly connected with the native neural tissue invasively.…”

Chitosan‐Based, Biocompatible, Solution Processable Films for In Vivo Localization of Neural Interface Devices

“…Current methods for visualization of neural interface device placement include use of fluorescent dyes, immunologic tissue staining, and electrolytic lesions. [23][24][25][26][27] Fluorescent dyes such as (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI), 3,3′-dioctadecyloxacarbocyanine perchlorate (DiO') can be used to coat devices that are subsequently penetrated into neural tissue. [28,29] These lipophilic dyes become fluorescent when incorporated into the neural membrane and undergo noncovalent binding.…”

“…Such arrays carry the added benefit of not penetrating into the brain and damaging fragile tissue. [23,26,27,36] However, these features also create challenges for localizing the position of the array, potentially limiting interpretation of neural signals acquired. We use a conformable conducting polymer-based electrocorticography array, the NeuroGrid, to record high spatiotemporal resolution electrophysiological data from the surface of the brain in adult rats and developing mice (postnatal days 5-14; Figure 4d).…”