A shuttered neural probe with on-chip flowmeters for chronic in vivo drug delivery

• Published in: Journal of microelectromechanical systems Vol. 15; no. 4; pp. 1025 - 1033
• Main Authors: Papageorgiou, D.P., Shore, S.E., Bledsoe, S.C., Wise, K.D.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-08-2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied fluid mechanics; Applied sciences; Biocompatibility; Cables; Central nervous system; Chemicals; Dielectrics; Drug delivery; Drug delivery systems; Exact sciences and technology; Flowmeters; Fluid dynamics; Fluidics; Fundamental areas of phenomenology (including applications); In vivo; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Micromechanical devices and systems; Neural prostheses; Orifices; Physics; Precision engineering, watch making; Probes; Pulse measurements; Ribbons; Shutters; Silicon; Polyimide; Dielectric materials; Flow measurement; Central nervous system; Shutter; Drug dispensation; System on a chip; Experimental study; In vivo; Heat source; Flowmeter; Heating; Microvalves; Silicon; Compatibility; Microelectromechanical device; Microfluidics; Fluidics; Micropump
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2005.863733

This paper describes the development of shutters, fluidic ribbon cables, and flowmeters for use on bulk-micromachined neural probes. The resulting devices permit electrical recording, stimulation, and chemical drug delivery in the central nervous system at the cellular level. Dielectric shutters reduce unintended drug delivery by a factor of about 25 compared with an open orifice, while silicon fluidic cables are 1.5 times more flexible than the 70 mum-ID polyimide tubing previously used. A pulsed thermal flowmeter integrated on the probe allows verification of drug delivery on a per-channel basis with a resolution of 150 pL/s. Thermal time constants are about 60 mus, allowing multiple measurements within one delivery pulse while restricting any tissue heating to negligible levels. Finally, test structures have shown the process compatibility of on-chip thermopneumatic microvalves and micropumps. The fabrication of these fluidic structures (microchannels, shutters, cables, valves, and pumps) requires only two masks in addition to the eight normally used for passive probes, providing important new capabilities for use in neurophysiological research and neural prostheses