6 micrometer polyimide micro-ECoG (64 or 1024 channels, 20 micrometer sites at 200 micrometer pitch) coated with a thin adhesive PVA/PTPM hydrogel that sticks to the brain without sutures and resists fibrosis. Wu Ting's lab at CIBR Beijing with Qiu Dong at ICCAS; 16 weeks subdural in rats (Advanced Science 2025).
Independent, source-linked catalog sheet. Not a manufacturer-issued datasheet, regulatory decision or instructions for clinical use. Human evidence does not establish approval. Source-specific restrictions, conflicts and missing specifications are retained below.
A subdural micro-ECoG array carrying a thin ionically conductive hydrogel layer. The layer bridges the stiffness gap between polyimide and brain, adheres on contact to wet brain surface, and reduces the fibrous capsule that normally raises impedance over weeks. Built by Wu Ting’s group at the Chinese Institute for Brain Research, Beijing (CIBR) with Qiu Dong’s group at the Institute of Chemistry, Chinese Academy of Sciences. Published 8 October 2025 in Advanced Science, DOI 10.1002/advs.202515453, PMC12713035, CC BY 4.0. The full text was read via Europe PMC; CIBR’s Chinese release (8 October 2025) gives the same figures.
64-channel (long-term recordings) and 1024-channel (acute cortical mapping) arrays; a 4 mm disc variant for histology [1]
Substrate
6 µm polyimide [1]
Sites
20 µm diameter at 200 µm pitch for the 1024-channel design, with PEDOT:PSS electroplated on the gold [1]
Hydrogel layer
About 10 µm thick, conductivity about 2 S/m, chosen by COMSOL finite-element modelling; a 100 µm layer attenuated amplitude and spatial resolution [1][2]
Materials and fabrication
Field
Value and source scope
Array process
4-inch silicon wafer; 3 µm PI2611 polyimide cured at 300 C; Ti 10 nm / Au 200 nm by lift-off with AR-N 4340 resist; second 3 µm polyimide; RIE with AZ 4620 mask to define contours and pads; release in deionized water [1]
Packaging
64-channel: anisotropic conductive film to a flat flexible cable. 1024-channel: gold ball bonding to a flat flexible cable with Molex connectors for an Intan 128-channel headstage [1]
Hydrogel
Heteronetwork of hydrophilic polyvinyl alcohol and hydrophobic poly(3-trimethoxysilyl propyl methacrylate) (PTPM); scrape-coated onto the array, gelled in place by pulsed 365 nm UV and solvent exchange [1]
Hydrogel properties
Young’s modulus 109.4 ± 19.5 kPa; adhesion about 25.2 kPa to wet brain by dry cross-linking, so no sutures; low swelling from the hydrophobic component; reversible removal [1][2]
Performance envelope
Field
Value and source scope
Acute impedance rise
About 20 times lower than a conventional µECoG [1][2]
Tissue response
At 8 weeks in rats, less glial activation and almost no fibrous capsule than uncoated electrodes [2]
Chronic signal
Steady-state visual evoked potential SNR kept 94.8% of its starting value at 16 weeks; uncoated arrays fell to 69.5% [1][2]
Mapping
1024-channel acute rat cortical mapping with sub-millimeter spatial resolution preserved under the 10 µm hydrogel [2]
Limits
Rat only, with the long recording done on the 64-channel version and the 1024-channel version used acutely. The paper reports the 20 µm and 200 µm pitch for the 1024-channel array; the 64-channel geometry is blank here.
References
Chen L et al., Long-Term Stable Subdural Recordings Enabled by Fibrosis-Resistant Hydrogel-Integrated µECoG Arrays, Advanced Science (2025), PMC12713035, DOI 10.1002/advs.202515453.