Cellular Wireless Energy Harvesting for Smart Contact Lens Applications [Education Corner]

An energy harvester for a smart contact lens that monitors the glucose level of a user has been developed and demonstrated. The energy harvester captures a smartphone's second-generation (2G) cellular emission and rectifies it into dc power to operate on-lens microelectronics for glucose detection and wireless data transmission. The energy harvester can reach a maximum radio frequency (RF)-to-dc power conversion efficiency of 47%. An electrically realistic human eye model was designed and fabricated using three-dimensional (3-D) printing technologies to assist in various measurements of the proposed energy harvester. For accessibility and ease of measurements, the proof-of-concept rectifier for the harvester has been designed on a 10 mm ? 30 mm ? 0.8 mm two-layer FR4 printed circuit board (PCB). The end design demonstrates that an energy harvester on a smart contact lens is able to produce 1 mW of dc power at 2.1 V via cellular emission from a smartphone placed 18 cm away.