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1.
Biosens Bioelectron ; 77: 589-97, 2016 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-26476599

RESUMEN

A safe, compact and robust means of wireless energy transfer across the skin barrier is a key requirement for implantable electronic devices. One possible approach is photovoltaic (PV) energy delivery using optical illumination at near infrared (NIR) wavelengths, to which the skin is highly transparent. In the work presented here, a subcutaneously implantable silicon PV cell, operated in conjunction with an external NIR laser diode, is developed as a power delivery system. The biocompatibility and long-term biostability of the implantable PV is ensured through the use of an hermetic container, comprising a transparent diamond capsule and platinum wire feedthroughs. A wavelength of 980 nm is identified as the optimum operating point based on the PV cell's external quantum efficiency, the skin's transmission spectrum, and the wavelength dependent safe exposure limit of the skin. In bench-top experiments using an external illumination intensity of 0.7 W/cm(2), a peak output power of 2.7 mW is delivered to the implant with an active PV cell dimension of 1.5 × 1.5 × 0.06 mm(3). This corresponds to a volumetric power output density of ~20 mW/mm(3), significantly higher than power densities achievable using inductively coupled coil-based approaches used in other medical implant systems. This approach paves the way for further ministration of bionic implants.


Asunto(s)
Materiales Biocompatibles Revestidos/síntesis química , Diamante/química , Suministros de Energía Eléctrica , Prótesis e Implantes , Energía Solar , Transferencia de Energía , Diseño de Equipo , Análisis de Falla de Equipo , Ensayo de Materiales
2.
Biomed Microdevices ; 17(3): 9952, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25877379

RESUMEN

High density electrodes are a new frontier for biomedical implants. Increasing the density and the number of electrodes used for the stimulation of retinal ganglion cells is one possible strategy for enhancing the quality of vision experienced by patients using retinal prostheses. The present work presents an integration strategy for a diamond based, high density, stimulating electrode array with a purpose built application specific integrated circuit (ASIC). The strategy is centered on flip-chip bonding of indium bumps to create high count and density vertical interconnects between the stimulator ASIC and an array of diamond neural stimulating electrodes. The use of polydimethylsiloxane (PDMS) housing prevents cross-contamination of the biocompatible diamond electrode with non-biocompatible materials, such as indium, used in the microfabrication process. Micro-imprint lithography allowed edge-to-edge micro-scale pattering of the indium bumps on non-coplanar substrates that have a form factor that can conform to body organs and thus are ideally suited for biomedical applications. Furthermore, micro-imprint lithography ensures the compatibility of lithography with the silicon ASIC and aluminum contact pads. Although this work focuses on 256 stimulating diamond electrode arrays with a pitch of 150 µm, the use of indium bump bonding technology and vertical interconnects facilitates implants with tens of thousands electrodes with a pitch as low as 10 µm, thus ensuring validity of the strategy for future high acuity retinal prostheses, and bionic implants in general.


Asunto(s)
Terapia por Estimulación Eléctrica/instrumentación , Microelectrodos , Nanodiamantes/química , Nanodiamantes/ultraestructura , Semiconductores , Prótesis Visuales , Animales , Conductividad Eléctrica , Electrodos Implantados , Humanos , Análisis por Micromatrices/instrumentación , Impresión Molecular/métodos , Integración de Sistemas , Agudeza Visual/fisiología
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