Micromachined Flexible Silicon Solar Cells as a Power Supply for Smart Contact Lenses

Abstract

This article reports the fabrication, characterization, implementation, and microsystem integration of micromachined flexible silicon solar cells to supply electric power to smart contact lenses. Single silicon solar cell shows the open circuit voltage (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</inf> ) of 0.5 and 0.55 V Under indoor and outdoor lighting conditions, respectively. The V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</inf> enhanced to 1.25 and 1.65 V after making series connections between three cells. The maximum power output of 50 µW and 2.7 mW are recorded under indoor and outdoor lighting conditions. Furthermore, a power management IC is used to boost up the voltage to 3.3 V and efficiently store or use the generated energy.