Electromechanical modeling of eye fatigue detecting using flexible piezoelectric sensors

Eye fatigue has attracted significant interest due to its potential harm to human daily activities. An ultrathin flexible piezoelectric sensor was currently designed and fabricated to detect eye fatigue by deforming together with the eyelid epidermis. Herein we develop a theoretical model to illustrate the correlation between the eyelid motion and the signals output by the piezoelectric sensor. The theoretical predictions on the eyelid motion based on the measured electrical output agree well with the in vivo observations in experiment. A simple scaling law is established to evaluate the impacts of different parameters on the function ability of the flexible piezoelectric sensor. The results may provide useful guidelines for designing and optimizing similar devices for alike biological motions.