Biocompatible benzocyclobutene (BCB)-based neural implants with micro-fluidic channel

Poly-benzocyclobutene (BCB)-based intracortical neural implant was fabricated, in which micro-fluidic channel was embedded to deliver drug solutions. BCB presents several attractive features for chronic applications: flexibility, biocompatibility, desirable chemical and electrical properties, and can be easily manufactured using existing batch micro-fabrication technology. The fabricated implants have single shank with three recording sites (20 mum x 20 mum) and two reserviors (inlet and outlet). The channel had large volume (40 mum width and 10 mum height), and hydrophobic surface to provide a high degree of chemical inertness. All the recording sites were positioned near the end of the shank in order to increase the probability of recording neural signals from a target volume of tissue. In vitro cytotoxicity tests of prototype implants revealed no adverse toxic effects on cultured cells. The implant with a silicon backbone layer of 5-10 mum was robust enough to penetrate rat's pia without buckling, a major drawback of polymer alone. The averaged impedance value at 1 KHz was similar to1.2 MOmega. Simultaneous recordings of neural signals from barrel cortex of a rat were successfully demonstrated. (C) 2004 Elsevier B.V. All rights reserved.