Plasma-assisted atomic layer deposition of Al2O3 and parylene C bi-layer encapsulation for chronic implantable electronics
- 27 August 2012
- journal article
- research article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 101 (9), 093702
- https://doi.org/10.1063/1.4748322
Abstract
Encapsulation of biomedical implants with complex three dimensional geometries is one of the greatest challenges achieving long-term functionality and stability. This report presents an encapsulation scheme that combines Al2O3 by atomic layer deposition with parylene C for implantable electronic systems. The Al2O3-parylene C bi-layer was used to encapsulate interdigitated electrodes, which were tested invitro by soak testing in phosphate buffered saline solution at body temperature (37 °C) and elevated temperatures (57 °C and 67 °C) for accelerated lifetime testing up to 5 months. Leakage current and electrochemical impedance spectroscopy were measured for evaluating the integrity and insulation performance of the coating. Leakage current was stably about 15 pA at 5 V dc, and impedance was constantly about 3.5 MΩ at 1 kHz by using electrochemical impedance spectroscopy for samples under 67 °C about 5 months (approximately equivalent to 40 months at 37 °C). Alumina and parylene coating lasted at least 3 times longer than parylene coated samples tested at 80 °C. The excellent insulation performance of the encapsulation shows its potential usefulness for chronic implants.This publication has 24 references indexed in Scilit:
- Role of hydrogen in the surface passivation of crystalline silicon by sputtered aluminum oxideProgress in Photovoltaics: Research and Applications, 2010
- Silicon surface passivation by ultrathin Al2O3 films synthesized by thermal and plasma atomic layer depositionPhysica Status Solidi (RRL) – Rapid Research Letters, 2010
- Characterization of parylene C as an encapsulation material for implanted neural prosthesesJournal of Biomedical Materials Research Part B: Applied Biomaterials, 2010
- The insulation performance of reactive parylene films in implantable electronic devicesBiomaterials, 2009
- Multiscale requirements for bioencapsulation in medicine and biotechnologyBiomaterials, 2009
- Integrated wireless neural interface based on the Utah electrode arrayBiomedical Microdevices, 2008
- The brain tissue response to implanted silicon microelectrode arrays is increased when the device is tethered to the skullJournal of Biomedical Materials Research Part A, 2007
- Low Temperature (<100°C) Deposition of Aluminum Oxide Thin Films by ALD with O[sub 3] as OxidantJournal of the Electrochemical Society, 2006
- The determination of coating performance using electrochemical impedance spectroscopyElectrochimica Acta, 1994
- Poly‐para‐xylelene: Its chemistry and application in coating technologyPolymer Engineering & Science, 1976