PDMS/Uhmwpe Dura Mater Substitute Laminated with Conductive Graphene for Intracranial Pressure Sensing

Dura mater, which is the outermost meninges under the skull, functions to protect the central nervous system. Brain tumor, subdural haematoma, trauma brain injuries and improper mending of dura mater may cause encephalocele, epilepsy, hydrocephalus (leakage of cerebrospinal fluid (CSF)) and infections. Consequently, these defects should be mended using dura replacements timely. Bio‐electronic grafts with high sensitivity, stretchability, multidirections and multifunctions are desired to address the issues in medicine. Here, we developed and fabricated soft, compliant, transparent and biocompatible electronic dura mater (e-dura) which matches the mechanical property and mimics the structure of natural dura mater, and can simultaneously act to monitor intracranial pressure change via piezo-resistivity sensing. The e-dura is a hierarchical structure consisting of hybridization of polydimethylsiloxane (PDMS) with biaxially stretched nanoporous ultrahigh molecular weight polyethylene (UHMWPE) membrane laminated with an electronically conductive chemical vapor grown mono layer graphene. It is fabricated by firstly laminating the UHMWPE membrane with a monolayer graphene followed by hybridization with the PDMS elastomer. Before hybridization with graphene covered UHMWPE membrane, the PDMS monomer and crosslinker were diluted inside hexane solvent to form a dilute solution mixture. The dilute solution mixture was then introduced onto the UHMWPE nanoporous membrane via spin coating. Strong interfacial bonding between PDMS and UHMWPE was achieved via the infiltration of dilute PDMS monomer solutions into the nanopores of UHMWPE membrane and subsequent nanoconfinement of PDMS polymer upon temperature induced crosslinking. The resulting e-dura exhibits high optical transparency, low friction coefficient, high piezoresistive gauge factor in excess of 1300 and tensile modulus and ductility mimicking human dura. Thus the new e-dura developed in this study shows strong potential in the application as e-dura for next-generation intracranial pressure sensing.