Efficient Communication and Powering for Smart Contact Lens with Resonant Magneto-Quasistatic Coupling

TL;DR

The work explores wireless powering and data transmission to a smart contact lens via resonant magneto-quasistatic (MQS) coupling between a necklace transmitter and a lens receiver. Using coil design equations and finite-element simulations, it demonstrates resonant MQS operation achieving a channel capacity of $4.5\text{ Mbps}$ over a $1\ \text{MHz}$ bandwidth at an axial separation of $15\ \text{cm}$ and lateral offset $>9\ \text{cm}$. Tissue permeability effects are negligible for MQS frequencies below $30\text{ MHz}$, ensuring tissue-insensitive magnetic coupling. The system remains robust under angular, lateral, and axial misalignments with path-loss variations within $10\ \text{dB}$, enabling AR/VR and health-monitoring applications on a smart contact lens.

Abstract

A two-coil wearable system is proposed for wireless communication and powering between a transmitter coil in a necklace and a receiver coil in a smart contact lens, where the necklace is invisible in contrast to coils embedded in wearables like spectacles or headbands. Magneto-quasistatic(MQS) field coupling facilitates communication between the transmitter in the necklace and the contact lens receiver, enabling AR/VR and health monitoring. As long as the receiver coil remains within the magnetic field generated by the transmitter, continuous communication is sustained through MQS field coupling despite the misalignments present. Resonant frequency tuning enhances system efficiency. The system's performance was tested for coil misalignments, showing a maximum path loss variation within $10 dB$ across scenarios, indicating robustness. Finite Element Method(FEM) analysis has been used to study the system for efficient wireless data transfer and powering. A communication channel capacity is $4.5 Mbps$ over a $1 MHz$ bandwidth. Simulations show negligible path loss differences with or without human tissues, as magnetic coupling remains unaffected at MQS frequencies below $30 MHz$ due to similar magnetic permeability of tissues and air. Therefore, the possibility of efficient communication and powering of smart contact lenses through a necklace is shown for the first time using resonant MQS coupling at an axial distance of $15cm$ and lateral distance of over $9cm$ to enable AR/VR and health monitoring on the contact lens.

Figures (12)

• Figure 1: Goal towards miniaturizing smart eyewear
• Figure 2: Proposed system based on Magnetic resonant coupling
• Figure 3: Circuit based on magnetic resonant coupling used to show that wireless power transfer is possible. Here the flat spiral circular coils are depicted by $L_{Tx}$ and $L_{Rx}$
• Figure 4: a. The side view shows how the coils are arranged in the simulation setup to mimic the position of a necklace and a contact lens while the front view shows the structure of the coil with the parameters for the chosen optimized model; c. 3D view of the simulation setup showing the simple human body model
• Figure 5: The eye tissues used for the simulations were cornea, aqueous humor, lens, and vitreous humor. The skin covers the receiver coil to depict the eyelid.