(Invited) Interactive Skin Display with Epidermal Stimuli Electrode

Abstract

In addition to the demand for stimuli-responsive sensors that can detect various vital signals in epidermal skin, the development of electronic skin displays that quantitatively detect and visualize various epidermal stimuli such as the temperature, sweat gland activity, and conductance simultaneously are of significant interest for emerging human-interactive electronics used in health-monitoring [1,2]. First of all, shape-deformable and self-healing EL displays (SSELD) are presented. Light emitting materials are fabricated by adding a certain amount of a plasticizer to elastomer containing light-emitting phosphors to obtain a viscoelastic composite that undergoes facile shape-deformation and recovery. A capacitive SSELD exhibits frequency-dependent field-induced light emission under alternating current (AC). A SSELD self-recovers its EL within few minutes of electrical failure with more than 100 cycles of failure-recovery operation endurance. By combining with a shape-deformable ionic liquid, a novel fiber display which exhibits excellent shape-deformable and self-healing EL performance. Second, a novel interactive skin display with epidermal stimuli electrode (ISDEE) is demonstrated, allowing for the simultaneous sensing and display of multiple epidermal stimuli on a single device. It is based on a simple two-layer architecture on a topographically patterned elastomeric polymer composite with light-emitting inorganic phosphors, upon which two electrodes are placed with a certain parallel gap. The ISDEE is directly mounted on human skin, which by itself serves as a field-responsive floating electrode of the display operating under AC. The AC field exerted on the epidermal skin layer depends on the conductance of the skin, which can be modulated based on a variety of physiological skin factors, such as the temperature, sweat gland activity, and pressure. Conductance-dependent field-induced electroluminescence is achieved, giving rise to an on-hand sensing display platform where we can directly sense and visualize a variety of human information.