A transparent epidural electrode array for use in conjunction with optical imaging

Multifunctional Flexible Biointerfaces for Simultaneous Colocalized Optophysiology and Electrophysiology

“…Figure 3d presents a quantitative performance comparison of the Au nanogrid electrodes with other state‐of‐the‐art transparent electrodes reported in the literature for electrophysiology, including flexible Au‐graphene mesh, [ 42 ] Au/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) mesh, [ 26 ] undoped graphene, [ 24 ] nitrogen‐doped graphene (N‐graphene), [ 43 ] platinum nanoparticle‐deposited graphene (Pt‐graphene), [ 44 ] CNT, [ 25 ] and rigid ITO. [ 22 ] The electrode impedance is normalized to electrode size to eliminate the influence of electrode dimension on impedance. The normalized impedance of the Au nanogrid electrodes is significantly smaller than those of Au‐graphene mesh, undoped graphene, N‐graphene, Pt‐graphene, CNT, and ITO electrodes.…”

“…[ 18,20 ] Recent developments in transparent microelectrodes based on indium tin oxide (ITO), graphene, carbon nanotube (CNT), and metal mesh have allowed for efficient light delivery through the electrodes to realize optical stimulation and electrophysiological recording of tissues under the electrodes with suppressed light‐induced electrical artifacts. [ 21–26 ] However, transparent microelectrodes alone cannot perform optical probing of the biological parameters. State‐of‐the‐art transparent microelectrode technologies rely on physically separated blocks (one is an external microscope or optical fiber and the other is a recording electrode) for multifunctional operations, which result in unfavorably large physical sizes and geometries and prevent further implantable applications.…”

Transparent arrays of bilayer-nanomesh microelectrodes for simultaneous electrophysiology and two-photon imaging in the brain

“…To highlight the performance of Au/PEDOT:PSS nanomesh microelectrodes, we compared the impedances from bilayer-nanomesh microelectrodes to previously reported major transparent MEAs from graphene, ITO, and state-of-the-art nontransparent ones ( 3 , 19 – 22 , 27 , 30 ). As expected, the Au/PEDOT:PSS nanomesh microelectrodes demonstrated 22× and 24× better impedance than the previous graphene ( 19 ) or ITO ( 22 ) ones of the same site area, while with slightly less transparency. Notably, at single-neuron size, the impedance of the transparent bilayer-nanomesh microelectrodes is comparable to the ones from nontransparent Michigan probes ( 27 ), highlighting the scalability of bilayer-nanomesh microelectrodes and the unique advantage from the bilayer-nanomesh approach.…”

Advanced Electrical and Optical Microsystems for Biointerfacing

“…Kunori et al combined ITO MEAs with an epifluorescence microscope to perform epidural cortical electrical stimulation and simultaneous optical imaging of signals from cortex neurons underneath the stimulating microelectrodes. [ 252 ] The ITO MEAs (thickness 100 nm, diameter 250 μm) are fabricated from a commercially available ITO‐coated PET film and a photolithography process. Although ITO/PET films are commercially available for optoelectronic applications, the cyclic flexibility and bending tolerance of those devices are inadequate for chronic applications in curvilinear biosurfaces because of the brittle nature of ITO.…”