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

• DOI: 10.1016/j.bios.2004.02.005
• Publication Date: 2004-03-20T16:11:47Z
• Authors: Keekeun Lee; Jiping He; Ryan Clement; Stephen Massia; Bruce Kim
• Keywords: Benzocyclobutene; Fluidics; Biocompatibility; Brain implant; Multielectrode array

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 microm x 20 microm) and two reserviors (inlet and outlet). The channel had large volume (40 microm width and 10 microm 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 microm was robust enough to penetrate rat's pia without buckling, a major drawback of polymer alone. The averaged impedance value at 1 KHz was approximately 1.2 MOmega. Simultaneous recordings of neural signals from barrel cortex of a rat were successfully demonstrated.