Energy and Accuracy Characterization of a Burst-Mode Range Sensing Approach for Smart Contact Lenses

Abstract

In this paper, we present the characterization of a new range sensing approach for use in emerging smart contact lens applications. Smart contact lenses offer a promising approach to treating the most common form of vision loss by using a tunable lens to accommodate for focal errors. A range sensor is an integral component of the system because it estimates an object's distance from the user in order to determine the target focal length. We performed an empirical study with custom fabricated coils in a mock eyeball setup to understand the energy-accuracy trade-offs of a burst-mode sensing approach based on transmission and reception of square pulses between the coils. We wirelessly transmitted square pulses between the coils and estimated the range of an object by sensing the received voltages and inferring the angular relationship between the two contacts. We demonstrate a functioning range sensing approach that can be implemented with energy as low as 1.8 nJ per measurement with at least 95% accuracy.