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

This letter presents the first fabrication and characterization of a biodegradable coaxial cavity resonator, focusing on the measurement of complex permittivity of encapsulation as well as |S₁₁| and impedance parameters. The resonator components are 3D-printed from plant-based resin, coated with silver-coated copper flakes, and enclosed by a laser-cut zinc membrane. A monopole coupler antenna, inspired by the “Great Seal Bug,” is co-designed with the cavity to enable near-field coupling and achieve frequency-selective, near- 50 Ω impedance-matched wireless sensing. Numerical and experimental analysis of the gap between post and membrane (G-post), and between the coupler antenna and post, resulted in| S₁₁ | of −30.3 dB at 1.7 GHz, and a quality factor of 307, outperforming existing flat biodegradable resonators. A 40-MHz resonance shift is observed with a 20 μm variation in G-post, highlighting the resonator’s high sensitivity to membrane position. This system enables battery-free wireless sensing with biodegradable antennas for biodiversity monitoring. ... Read more

The emergence of a new family of wireless biodegradable sensors marks a groundbreaking leap in ecological and environmental sensing. These biodegradable devices can collect a wide range of data in agriculture, climate research, forestry, water management, and biodiversity protection. Manufactured primarily from environmentally safe transient materials for sensing and data transmission, these systems undergo controlled degradation after use, minimizing environmental electronic waste. Here, a critical review of key aspects in the development and application of biodegradable sensors is performed for ecological and environmental monitoring. First, the different materials utilized in the development of biodegradable environmental monitoring devices and their applications are explored. The relevant degradation mechanisms, including hydrolysis, oxidation, photodegradation, and micro-organism action are examined as a function of environmental conditions. Then compatible and non-toxic fabrication techniques are investigated for building biodegradable sensors, emphasizing their scalability and potential for mass production. Finally, system-level considerations are discussed for sustainable powering of these devices, ensuring efficient operation while maintaining environmental sustainability. By surveying a broad spectrum of applications and ongoing advancements, it is argued that biodegradable sensors have a transformative potential in advancing sustainable, widespread, and cost-effective ecological and environmental monitoring solutions. ... 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