Ultra‐Adaptable and Wearable Photonic Skin Based on a Shape‐Memory, Responsive Cellulose Derivative

Abstract

Photonic skins enable a direct and intuitive visualization of various physical and mechanical stimuli with eye-readable colorations by intimately laminating to target substrates. Their development is still at infancy compared to that of electronic skins. Here, an ultra-adaptable, large-area (10 × 10 cm 2 ), multipixel (14 × 14) photonic skin based on a naturally abundant and sustainable biopolymer of a shape-memory, responsive multiphase cellulose derivative is presented. The wearable, multipixel photonic skin mainly consists of a photonic sensor made of mesophase cholesteric hydroxypropyl cellulose and an ultraadaptable adhesive layer made of amorphous hydroxypropyl cellulose. It is demonstrated that with multilayered flexible architectures, the multiphase cellulose derivative-based integrated photonic skin can not only strongly couple to a wide range of biological and engineered surfaces, with a maximum of ≈180 times higher adhesion strengths compared to those of the polydimethylsiloxane adhesive, but also directly convert spatiotemporal stimuli into visible color alterations in the large-area, multipixel array. These colorations can be simply converted into 3D strain mapping data with digital camera imaging.

Self-Adherent Biodegradable Gelatin-Based Hydrogel Electrodes for Electrocardiography Monitoring

“…Considering the ease of the molding process with conductive hydrogel-forming solutions, large-scale, cost-effective fabrication is possible. Moreover, by introducing nano- or micro-structures onto the surface of hydrogel electrodes, the adhesive performance of the electrodes to target tissues can be improved [ 45 , 46 ]. Self-adherent hydrogel electrodes with good biocompatibility and flexibility could be integrated into motion detection sensors and into wearable sensors for medical monitoring.…”

Smart Sensing Systems Using Wearable Optoelectronics

“…The entire forms of devices using PUA elastomers can endure up to extreme stretchability (2500%) without failure. In addition to the good mechanical stability of underlying substrates, the conformal and robust coupling issues of skin have been another concern for wearable optoelectronic sensors . Reliable and robust coupling to wet, soft, and strain‐induced tissues or surfaces is desirable, as these features promote reliable acquisition of sensing signals.…”

“…Many recent efforts have been made to enhance conformal and robust coupling. Yi et al developed an ultra‐adaptable and stably skin‐mountable wearable photonic device using hydroxypropyl cellulose (HPC) . HPC exhibited self‐assembly, controllable swelling behavior, and shape‐memory capabilities using a light source, which can be utilized for reversible adhesive materials to diverse surfaces.…”

Biomimetic Meta‐Structured Electro‐Microfluidics

“…[27] Excellent sensors integrated into skin chips require accurate and sensitive detection of relevant indicators. [27] Excellent sensors integrated into skin chips require accurate and sensitive detection of relevant indicators.…”