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bioRxiv · 10.1101/2025.09.02.673516

PolyGraph - Flexible, Biocompatible & Electrically Optimised Graphene-Polymer Composites for Next-Generation Neural Interfaces

Maughan, J.·Woods, I.·O'Connor, C.·Quintana-Sarti, P.·Caffrey, E.·Munuera, J. M.·Dervan, A.·Lopez Valdes, A.·Mamad, O.·Caldwell, M. A.·O'Brien, F. J.·Coleman, J. N.
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Abstract

Neural interfacing materials must deliver exceptional electrochemical performance, while integrating safely with the central nervous system. In this study we develop PolyGraph, a flexible, conductive, and biocompatible graphene-polycaprolactone (PCL) nanocomposite designed to strike this balance, which enables fabrication of conformable multichannel microelectrode arrays. Optimised liquid-phase exfoliation produces conductive, biocompatible PVP-stabilised graphene nanosheets, which are incorporated into PCL to form flexible, processable composites - PolyGraph. This material demonstrates bio- and immuno-compatibility with sensitive primary and iPSC-derived neuronal and glial cells. PolyGraph achieves low impedance ([~]1.6 {Omega} cm2 @ 1 kHz) and high charge injection capacity (11.7 mC/cm2 for a 100 ms pulse), enhanced by NaOH surface roughening and AuPd coating. Leveraging their processability, PolyGraph composites are fabricated into flexible, individually isolated microneedle electrode arrays with biomimetic soft hyaluronic acid backings. These arrays demonstrate bidirectional neural interfacing capabilities, enabling both the delivery of controlled stimulation pulses in physiological buffer and high-resolution neuronal recording in murine brain slices, with machine learning-based event classification. Together, these advances establish PolyGraph as an optimal material platform for next-generation brain-computer interfaces and soft bioelectronic devices. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/673516v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@9beea5org.highwire.dtl.DTLVardef@150be08org.highwire.dtl.DTLVardef@1ec24d2org.highwire.dtl.DTLVardef@658209_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical Abstract & TOC Text PolyGraph, a flexible graphene-polycaprolactone nanocomposite, unites conductivity, biocompatibility, and processability for next-generation neural interfaces. Fabricated into microneedle arrays with ultra-flexible backings, PolyGraph enables bidirectional neuronal recording and stimulation in brain tissue, advancing brain-computer interface (BCI) and soft bioelectronic applications.

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Maughan, J., Woods, I., O'Connor, C., Quintana-Sarti, P., Caffrey, E., Munuera, J. M., Dervan, A., Lopez Valdes, A., Mamad, O., Caldwell, M. A., O'Brien, F. J., Coleman, J. N.. 2025-09-07. PolyGraph - Flexible, Biocompatible & Electrically Optimised Graphene-Polymer Composites for Next-Generation Neural Interfaces. https://doi.org/10.1101/2025.09.02.673516

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