Flexible Eyelid Pressure and Motion Dual-Mode Sensor Using Electric Breakdown-Induced Piezoresistivity and Electrical Potential Sensing.

Multiple ocular surface disorders are associated with the mechanical properties of the interface between the eyelid and cornea. Determining eyelid pressure is vital for diagnosing and preventing these disorders. However, current measurements rely on flat piezoresistive pressure sensor arrays that lack eye-motion sensing capabilities, resulting in discomfort and measurement inaccuracies. This study develops and evaluates an integrated, curved, flexible, dual-mode sensor array for simultaneous eyelid pressure and motion detection, using soft thermoplastic polyurethane (TPU) films as transducers and substrates. A novel manufacturing method based on the electrical breakdown of the TPU film enables piezoresistive pressure sensing, achieving a pressure detection limit of 3.2 Pa. Eyelid motion is measured through electrical potential sensing, where changes in eyelid position alter the electric potentials at the receiving electrodes. The sensor's performance was validated with animal experiments involving rabbit eyes; eyelid pressure was successfully measured during eye opening and blinking. This flexible dual-mode eyelid sensor holds promise for monitoring eyelid pressure and assessing ocular surface disorders.