Flexible polyimide-based intracortical electrode arrays with bioactive capability

Abstract

The promise of advanced neuroprosthetic systems to significantly improve the quality of life for a segment of the deaf, blind, or paralyzed population hinges on the development of an efficacious, and safe, multichannel neural interface for the central nervous system. The candidate implantable device that is to provide such an interface must exceed a host of exacting design parameters. We present a thin-film, polyimide-based, multichannel intracortical Bio-MEMS interface manufactured with standard planar photo-lithographic CMOS-compatible techniques on 4-in silicon wafers. The use of polyimide provides a mechanically flexible substrate which can be manipulated into unique three-dimensional designs. Polyimide also provides an ideal surface for the selective attachment of various important bioactive species onto the device in order to encourage favorable long-term reactions at the tissue-electrode interface. Structures have an integrated polyimide cable providing efficient contact points for a high-density connector. This report details in vivo and in vitro device characterization of the biological, electrical and mechanical properties of these arrays. Results suggest that these arrays could be a candidate device for long-term neural implants.

Metabolic and behavioral deficits following a routine surgical procedure in rats

“…At later time points, typical inflammatory cells or hemorrhaging has not been observed [47], while others have documented neuronal cell loss and macrophages up to 112 days after the implant [6,41,42,44]. As a testament to the transitory nature of this mechanically induced wound healing response, electrode tracks could not be found in animals after several months when the electrode was inserted and quickly removed [6,13,35,47]. We have shown a similar effect with FDG, since glucose metabolism returned to normal levels within seven days if the microdialysis probe was inserted and immediately removed [39].…”

A lithographically-patterned, elastic multi-electrode array for surface stimulation of the spinal cord

“…The MEA substrate PDMS, with a Young's modulus of 0.4−1.0 MPa, is significantly more elastic than parylene and polyimide, whose Young's moduli are approximately 4−4.5 GPa and 2.3−2.8 GPa, respectively (Armani, 1999;Rousche et al, 2001;Suzuki, 2003;Yang, 1998). Because of its greater elasticity, PDMS can confer not just flexible but also conformable interfacing with neural tissue.…”

Implanted intracortical electrodes as chronic neural interfaces to the central nervous system

“…Two promising works used Dexamethasone 10 during implantation resulting in decreased glial scarring and improvements to implant performance [83,96]. While the drug delivery of Dexamethasone was only during implantation, it is possible to combine this technique with constant drug delivery systems suggested by Rousche et al [97]. In their system, they etch drug delivery wells into a Michigan-like probe to deliver dextran.…”