Wearable Contact Lens for Electroretinography Signal Detection via Liquid Metal Composite Electrodes Coated with Silver Nanowire/Sodium Alginate

Electroretinography (ERG) is extensively employed to measure the electrical activity of the retinal tissue, and it requires corneal interfaces that are soft, conformal, stable, and low impedance. However, commercial rigid electrodes cause discomfort and are sensitive to eye motion. Many soft designs, such as graphene and hydrogel contact lenses, still suffer from high and unstable interfacial impedance. Here, we report a soft and stable ERG contact lens with liquid metal (LM) composite electrodes coated with silver nanowire/sodium alginate (AgNWs-SA). The wiring electrodes are patterned by direct writing of fumed silica nanoparticles/copper powder/liquid metal (FCL) composite ink onto a sodium alginate interlayer on a curved polydimethylsiloxane (PDMS) substrate, which have a high conductivity of ∼10⁵ S m^-1. The electrode surface in contact with the cornea is modified by dripping AgNWs-SA, effectively suppressing low-frequency impedance fluctuation to achieve stable signal acquisition while preventing leakage of the FCL ink, and the cell viability across the entire electrode exceeds 95%. The lens exhibits a lower electrochemical impedance of ∼806 Ω@100 Hz and greater stability than a commercial gold ring electrode. In vivo, it records full-field ERG with larger amplitudes, clearer oscillatory potentials, and improved 30 Hz flicker responses. A five-electrode array resolves center-to-periphery corneal potential gradients and maintains waveform consistency in semi-awake animals. Thus, the ERG contact lens enables high-fidelity single- and multi-electrode detection of ERG and paves a new path toward fabricating wearable ocular sensors.