Local de-insulation method for neural microneedle arrays

• A local de-insulation method was developed and applied in neural microneedle arrays.¹
• The fabrication method improves electrode contact and signal quality.¹
• It is relevant to Utah-style and next-generation arrays; Nature-published device engineering with near-term use.^{1 1}

Weekly enrichment (2026-07-20)

• The method was published in Nature’s Microsystems & Nanoengineering (2025) and introduces an etching-free “local de-insulation” technique for exposing the recording tips of silicon-based neural microneedle arrays such as the Utah Array.^{2 3}
• Instead of masking-and-etching, microneedle tips are pressed into a spin-coated, partially cured polydimethylsiloxane (PDMS) layer; the elastic PDMS seals the tips so a subsequent Parylene-C insulation layer, applied by chemical vapor deposition (CVD), cannot coat them.^{2 4}
• Withdrawing the array cleanly exposes the recording sites; the Parylene-C film thickens toward the fracture point to roughly 3 μm, and process parameters were tuned to control exposed-tip area.^{3 4}
• Fabricated arrays were 10 × 10 (100 electrodes), and the non-uniformity of exposed recording-site area across an array was measured at 3.32 ± 1.02%, indicating highly consistent tip exposure.^{2 3}
• In vivo testing achieved an average spike signal-to-noise ratio of 12.63 ± 6.64, supporting single-neuron recording capability.^{2 3}
• The arrays showed high stability and reliability in both mechanical performance and electrical characteristics, and the authors report better time efficiency than the conventional photoresist-mask-plus-etching route.^{2 5}
• A key advantage over etching is avoiding poorly controlled fracture locations that can cause Parylene-C to detach from the electrode shaft, reducing a known failure mode.⁵
• BCI/clinical implication: a simpler, more precise, and scalable fabrication path for high-density penetrating microelectrode arrays could improve yield and reliability for chronic cortical BCIs, though this report covers device engineering and acute in vivo validation rather than long-term human implantation (chronic human data not reported).^{2 6}

Footnotes

1. https://news.google.com/rss/articles/CBMiX0FVX3lxTFA2TGtlZ0Ztb19tUXNsYl9NVEROc2pfemdyek5rQzR1MjlKMi1xbEZVOE02VDVXelcxcWdhUjhXaWRZS3ZjTnVmeXBEc3FQcV93Wm5POFNqdU1aanpuUk9z?oc=5 ↩ ↩² ↩³ ↩⁴

2. https://www.nature.com/articles/s41378-025-00922-6 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

3. https://doi.org/10.1038/s41378-025-00922-6 ↩ ↩² ↩³ ↩⁴

4. https://nature.com/articles/s41378-025-00922-6.pdf ↩ ↩²

5. https://preview-www.nature.com/articles/s41378-025-00922-6 ↩ ↩²

6. https://www.eurekalert.org/news-releases/1092848 ↩