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Plasma‐enhanced chemical vapor deposited silicon carbide as an implantable dielectric coating
Author(s) -
Cogan Stuart F.,
Edell David J.,
Guzelian Andrew A.,
Ping Liu Ying,
Edell Robyn
Publication year - 2003
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.10152
Subject(s) - materials science , chemical vapor deposition , dissolution , amorphous solid , plasma enhanced chemical vapor deposition , coating , silicon carbide , silicon , analytical chemistry (journal) , composite material , chemical engineering , nanotechnology , optoelectronics , chromatography , chemistry , organic chemistry , engineering
Amorphous silicon carbide (a‐SiC) films, deposited by plasma‐enhanced chemical vapor deposition (PECVD), have been evaluated as insulating coatings for implantable microelectrodes. The a‐SiC was deposited on platinum or iridium wire for measurement of electrical leakage through the coating in phosphate‐buffered saline (PBS, pH 7.4). Low leakage currents of <10 −11 A were observed over a ±5‐V bias. The electronic resistivity of a‐SiC was 3 × 10 13 Ω‐cm. Dissolution rates of a‐SiC in PBS at 37 and 90°C were determined from changes in infrared absorption band intensities and compared with those of silicon nitride formed by low‐pressure chemical vapor deposition (LPCVD). Dissolution rates of LPCVD silicon nitride were 2 nm/h and 0.4 nm/day at 90 and 37°C, respectively, while a‐SiC had a dissolution rate of 0.1 nm/h at 90°C and no measurable dissolution at 37°C. Biocompatibility was assessed by implanting a‐SiC‐coated quartz discs in the subcutaneous space of the New Zealand White rabbit. Histological evaluation showed no chronic inflammatory response and capsule thickness was comparable to silicone or uncoated quartz controls. Amorphous SiC‐coated microelectrodes were implanted in the parietal cortex for periods up to 150 days and the cortical response evaluated by histological evaluation of neuronal viability at the implant site. The a‐SiC was more stable in physiological saline than LPCVD Si 3 N 4 and well tolerated in the cortex. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 856–867, 2003