Soft, thin skin-mounted power management systems and their use in wireless thermography

Significance Existing options for electrical power generation and storage in wearable electronics are incompatible with thin geometries, soft, stretchable mechanics, and lightweight construction needed for long‐lived, intimate interfaces with the skin. Here we demonstrate concepts that allow the integration of collections of thin, millimeter-scale solid-state batteries and multijunction solar cells into electrically interconnected arrays that simultaneously provide high-performance operation and soft, biocompatible mechanics at the system level. Examples in photovoltaic energy harvesting, storage, and overall power management illustrate some of the functional options with such platforms. Thin, wearable wireless sensors for skin thermography with capabilities in data logging demonstrate the combined use of components for energy storage, power management, digital memory, physiological monitoring, and wireless, near-field communications in an integrated, stretchable device architecture with the ability to establish robust, nonirritating measurement interfaces directly to the skin. Power supply represents a critical challenge in the development of body-integrated electronic technologies. Although recent research establishes an impressive variety of options in energy storage (batteries and supercapacitors) and generation (triboelectric, piezoelectric, thermoelectric, and photovoltaic devices), the modest electrical performance and/or the absence of soft, biocompatible mechanical properties limit their practical use. The results presented here form the basis of soft, skin-compatible means for efficient photovoltaic generation and high-capacity storage of electrical power using dual-junction, compound semiconductor solar cells and chip-scale, rechargeable lithium-ion batteries, respectively. Miniaturized components, deformable interconnects, optimized array layouts, and dual-composition elastomer substrates, superstrates, and encapsulation layers represent key features. Systematic studies of the materials and mechanics identify optimized designs, including unusual configurations that exploit a folded, multilayer construct to improve the functional density without adversely affecting the soft, stretchable characteristics. System-level examples exploit such technologies in fully wireless sensors for precision skin thermography, with capabilities in continuous data logging and local processing, validated through demonstrations on volunteer subjects in various realistic scenarios.