Dual-Junction Photovoltaic for Implantable Biosensor Platform

Traditional multi-junction solar cells aim to capture a broader spectrum of sunlight, thus maximizing absorption and minimizing energy losses. This is achieved by stacking layers of semiconductors with different bandgaps. Our dual-junction solar cell is novel in that it is centered around a very narrow range of wavelengths produced by the 730nm LED array on the externally worn device, thus semiconductors with varying bandgaps are not required. In addition, we present the fabrication and characterization of a dual-junction solar cell capable of powering an implantable biosensor platform. Solar cells were fabricated on n[Formula: see text]GaAs (100) substrates where precise epitaxial layers of AlGaAs/GaAs were designed and grown to define the tunnel junction and AlGaAs-GaAs and GaAs-GaAs solar cells. The biosensor platform uses a custom application-specific integrated circuit (ASIC), which is designed with 65 nm technology to detect interstitial glucose levels for individuals with Type I Diabetes. This continuous glucose monitor (CGM) is being developed as an implantable medical device that is controlled from an externally worn device and uses a proprietary protocol for optically powering and receiving data through the skin of an individual.