abstract
The design of neural electrodes has changed in the pastdecade,driven mainly by the development of new materials that open the possibilityof manufacturing electrodes with adaptable mechanical properties andpromising electrical properties. In this paper, we report on the mechanicaland electrochemical properties of a polydimethyl-siloxane (PDMS)composite with edge-functionalized graphene (EFG) and demonstrateits potential for use in neural implants with the fabrication of anovel neural cuff electrode. We have shown that a 200 & mu;m thick1:1 EFG/PDMS composite film has a stretchability of up to 20%, a Young'smodulus of 2.52 MPa, and a lifetime of more than 10000 mechanicalcycles, making it highly suitable for interfacing with soft tissue.Electrochemical characterization of the EFG/PDMS composite film showedthat the capacitance of the composite increased up to 35 times afterelectrochemical reduction, widening the electrochemical water windowand remaining stable after soaking for 5 weeks in phosphate bufferedsaline. The electrochemically activated EFG/PDMS electrode had a 3times increase in the charge injection capacity, which is more thandouble that of a commercial platinum-based neural cuff. Electrochemicaland spectrochemical investigations supported the conclusion that thiseffect originated from the stable chemisorption of hydrogen on thegraphene surface. The biocompatibility of the composite was confirmedwith an in vitro cell culture study using mouse spinalcord cells. Finally, the potential of the EFG/PDMS composite was demonstratedwith the fabrication of a novel neural cuff electrode, whose double-layeredand open structured design increased the cuff stretchability up to140%, well beyond that required for an operational neural cuff. Inaddition, the cuff design offers better integration with neural tissueand simpler nerve fiber installation and locking.
keywords
ELECTROCHEMICAL HYDROGEN STORAGE; ELECTRICAL-STIMULATION; DESIGN
subject category
Science & Technology - Other Topics; Materials Science
authors
Montoya, G; Wagner, K; Ryder, G; Naseri, ASZ; Faisal, SN; Sencadas, V; Panhuis, MIH; Spinks, GM; Wallace, GG; Alici, G; Officer, DL
our authors
Vitor Sencadas
Associate Professoracknowledgements
This work was financially supported by the Australian Research Council (ARC) Centre of Excellence Scheme (Project No. CE 140100012). The authors acknowledge use of the specialized facilities of the Materials Node of the Australian National Fabrication Facility (ANFF), the UoW Electron Microscopy Centre with the assistance of Dr. Mitchell J. B. Nancarrow, and the Surface Analysis Laboratory of the University of New South Wales.