Enabling the Refractive Index Modulation of Vision-Correcting Smart Contact Lens Utilizing an Optimized Design of Relay-Assisted Wireless Power Transfer

This letter reports on the optimized design of a relay-assisted wireless power transfer system that can be utilized to control the liquid crystal alignment for potential refractive index modulation in a proof-of-concept smart contact lens. This system produces 10.9 V output, surpassing the required voltage of 10 V to adjust the optical power from 0 diopter (focal length: ∞ mm) to 5 diopter (200 mm). The wireless power transfer system consists of a) an optimally designed transmitter coil, b) an optimally placed high quality-factored relay coil attached to the transmitter, and c) the power receiver on the smart contact lens for the focal length modulation shown in Fig.1. By designing the optimized distance between the transmitter and relay coils and coil turn-number of the transmitter, the maximum voltage output at the receiver coil was achieved resulting in the modulation of refractive index from 1.72 to 1.52 with the light-polarizing liquid crystal, indicating the focal length change from infinity to 200 mm. Through this optimized configuration, the developed wireless power transfer system successfully (1) achieved a 9.9 times improvement in peak output voltage from 1.1 V to 10.9 V at the receiver coil, and (2) activated the re-orientation of 5-μm thick light-polarizing liquid crystal with the produced peak output voltage, that (3) induced refractive index changes in liquid crystal structure from 1.72 to 1.52. This development demonstrated the potential application of the wirelessly powered smart contact lens for vision-correction in patients with far-/near-sightedness by successfully modulating the focal length between 0 and 5 diopters.