Sweat is an accessible biofluid that provides useful physiological information about the body’s biomolecular state and systemic health. Wearable sensors possess various advantageous features, such as lightweight design, wireless connectivity, and compatibility with human skin, that make them suitable for continuous monitoring. Wearable electrochemical sweat sensors can diagnose diseases and monitor health conditions by detecting biomedical signal changes in sweat. This paper discusses the state-of-the-art research in the field of wearable sweat sensors and the materials used in their construction. It covers biomarkers present in sweat, sensing modalities, techniques for sweat collection, and ways to power these sensors. Innovative materials are categorized into three subcategories: sweat collection, sweat detection, and self-powering. These include substrates for sensor fabrication, analyte detection electrodes, absorbent patches, microfluidic devices, and self-powered devices. This paper concludes by forecasting future research trends and prospects in material-based wearable non-invasive sweat sensors.

Nanomaterial-based self-healing electrodes have demonstrated significant potential in sensing and energy storage applications due to their ability to withstand electrical breakdowns at high electric fields. However, such electrodes often face mechanical challenges, such as cracking under stress, compromising stability and reliability. This review critically examines nanomaterial-based self-healing mechanisms, focusing on properties and applications in health monitoring, motion sensing, environmental monitoring, and energy storage. By comprehensively reviewing research conducted on dimension-based nanomaterials (OD, 1D, 2D, and 3D) for self-healing electrode applications, this paper aims to provide essential insights into design strategies and performance enhancements afforded by nanoscale dimensions. This review paper highlights the tremendous potential of harnessing dimensional nanomaterials to develop autonomously restoring electrodes for next-generation sensing and energy devices.

Epidermal sensors are pivotal components of next-generation wearable technologies. They offer transformative potential in health monitoring, motion tracking, and biomedical applications. This potential stems from their ultra-thin design, skin compatibility, and ability to continuously detect physiological signals. The long-term functionality relies on advanced power systems balancing flexibility, energy density, and environmental resilience. This review highlights four key power strategies: chemical batteries, biofuel cells, environmental energy harvesters, and wireless power transfer. Breakthroughs in multidimensional materials address challenges in ion transport, catalytic stability, and mechanical durability. Structural innovations mitigate issues like dendrite growth and enzyme degradation. These systems enable applications spanning biomarker analysis, motion sensing, and environmental monitoring. By integrating these advancements, this review concludes with a prospective outlook on future directions for epidermal sensor power systems.

The growing energy crisis and environmental challenges have spurred the development of sustainable energy storage solutions. This study synthesizes 3D porous Orange Peel-Lignin activated carbon (OPLAC) from orange peel waste and lignin using a two-step pyrolysis process with KOH activation. The OPLAC was combined with styrene-isoprene-styrene (SIS) and SUPER P conductive carbon black to create stretchable electrode composites with varying compositions (70:20:10, 60:30:10, and 50:40:10). Mechanical testing revealed that increasing the SIS content improved stretchability, with the 50:40:10 composition achieving 300% strain and retaining 95% durability after 100 cycles. However, higher SIS content reduced electrical conductivity, with the 70:20:10 composition showing the highest conductivity (12 S/cm) and the 50:40:10 the lowest (7 S/cm). The 60:30:10 composition offered a balance between flexibility and conductivity. These results demonstrate the potential of biomass-derived activated carbon for sustainable, high-performance supercapacitor electrodes, particularly for flexible electronics and wearable devices, while highlighting the valorization of agricultural and industrial waste in energy storage applications. Keywords: Stretchable electrode, activated carbon, orange peel waste, Lignin, flexible electronics