Article ID Journal Published Year Pages File Type
4962789 Sustainable Computing: Informatics and Systems 2016 14 Pages PDF
Abstract
Wearable technology is gaining popularity, with people wearing everything “smart” from clothing to glasses and watches. Present-day wearables are typically battery-powered, and their limited lifetime has become the critical issue. Most devices need recharging every few days or even hours, falling short of the expectations for a truly satisfactory user experience. This paper presents the design, implementation and in-field evaluation of InfiniTime, a novel sensor-rich smart bracelet powered by energy harvesting. It is designed to achieve self-sustainability using solar cells with only modest indoor light levels and thermoelectric generators (TEG's) with small temperature gradients from the body heat. The wearable device is equipped with an ultra-low power camera and a microphone, in addition to accelerometer and temperature sensors commonly used in commercial devices. Experimental characterization of the fully operational prototype demonstrates a wide range of energy optimization techniques used to achieve self-sustainability with harvested energy only. Our experiments in real-world scenarios show an average of up to 550 μW for photovoltaic in indoor and 98 μW for TEG with only 3 ° temperature gradient and up to 250 μW for 5° gradient. Simulations using energy intake measurements from solar and TEG modules confirm that InfiniTime achieves self-sustainability with indoor lighting levels and body heat for several realistic applications featuring data acquisition from the on-board camera and multiple sensors, as well as visualization and wireless connectivity. The highly optimized low-power architecture of the presented prototype features image acquisitions at 1.15 frames per second, powered only from the energy harvesters.
Related Topics
Physical Sciences and Engineering Computer Science Computer Science (General)
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