We introduce Green Cough Sense, a biodegradable, battery-free smart face mask that incorporates a flexible, passive microphone for sensing cough acoustics in pulmonology. The device integrates a mesoscale-patterned 3 by 3 array of 1 cm2 circular drum-like membranes with a patch antenna, a planar resonator comprising a metallic radiating patch over a grounded dielectric substrate. Cough-induced acoustic vibrations are transduced into measurable shifts in the electromagnetic reflection coefficient (|S11|), which are measured by a vector network analyzer operating in zero-span mode for high-fidelity characterization. The system is fabricated entirely from sustainably sourced, biodegradable materials, including cellulose acetate, poly(lactic acid), and zinc, via a new green manufacturing process that combines laser machining with solvent- and adhesive-free low-temperature lamination technique with maximum bonding strength reaching 5.8 N/mm. Experimental validation of the mechanoacoustic response demonstrates absolute sensitivity of 0.045 μm/Hz; in vitro characterizations under monotone excitation show sensitivity of 0.13%/Pa; in situ validation with human participants confirms detection of mild, moderate, and severe cough events. Biodegradation under industrial composting confirms material breakdown with over 90% weight loss after 100 days, supporting a zero-waste end-of-life strategy. ... Read more

In resource-limited clinical settings, sweat chloride testing frequently departs from standardized protocols, leading to unreliable measurements and elevated false-negative rates. A central contributor to this problem is the absence of a unified, passive device for efficient sweat collection and sweat-rate–normalized quantitative chloride sensing. Here we report a dual-mode cellulose-based epidermal microfluidic sensory system that enables sweat-rate–normalized chloride analysis by integrating real-time sweat-volume quantification with distance-based and colorimetric chloride sensing in a fully passive skin-conformal patch. The laser-engraved paper microfluidic channel quantifies sweat volume with a sensitivity of 6.5 mm.µl⁻¹ and a detection limit of 1.0 µl for localized sweat-rate estimation. Simultaneously, distance-based chloride sensing based on reverse Mohr chemistry provides a linear response across 0–100 mmol.l^⁻1 with a sensitivity of 24.8 mm.mM^⁻1 and a limit of detection of 0.1 mmol.l^⁻1, while companion colorimetric zones enable rapid visual classification under low-sweat conditions. The device shows high repeatability (CV = 0.31%), selectivity against common sweat interferents, and storage stability for more than 70 days (CV = 9.25%), a 136% increase from conventional distance-based devices. Pilot on-body measurements capture dynamic sweat chloride changes during exercise and electrolyte modulation, highlighting the value of sweat-rate normalization for physiologically meaningful interpretation. With an estimated material cost of less than USD 0.02 per device, 80% less than the reported cost of distance-based devices, this platform provides a scalable approach to sweat chloride testing in resource-limited clinical settings. ... Read more

Muscle plays a vital role in movement and metabolic regulation, establishing it as a cornerstone of overall health. Monitoring muscular parameters is critical for disease diagnosis, post-surgical recovery, and human–machine interface control. In recent decades, numerous technologies have emerged to monitor muscular biophysical and biochemical processes. The field has transitioned significantly from reliance on large, clinic-bound instrumentation to the development of miniaturized wearable and implantable systems capable of continuous real-time monitoring in everyday settings. This article presents a critical overview of recent advances, with a focus on material and device innovations in muscular monitoring. Starting with the fundamental characteristics of muscle tissue and the physiological origins of biosignals, the discussion subsequently shifts to recent developments in wearable and implantable bioelectronic systems tailored to monitor electrophysiological, biomechanical, and tissue oxygenation signals. Finally, current research challenges and outline emerging opportunities are highlighted in muscular monitoring. Owing to its interdisciplinary nature and growing societal demand for personalized healthcare, muscular monitoring is poised to catalyze transformative innovations in both clinical and consumer applications. ... Read more