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The increasing use of electronic devices raises concerns about resource availability and end‐of‐life management, particularly regarding conductors for interconnects and sensing elements. While gold and silver are the leading materials for interconnects, they pose challenges related to scarcity, cost, and toxicity. Zinc offers a promising alternative due to its good electrical conductivity, non‐toxicity, abundance, and affordability. However, challenges in achieving high conductivity and waste generation from processing techniques like screen‐printing remain. To address this, a zinc ink optimizes for 3D printing is proposed, using active zinc particles in a shellac matrix. The methods, including chemical and photonic sintering, achieve conductivities of up to 8.74•104 S m⁻¹ on paper substrates, with stable performance over a range of 30%–70% relative humidity at 15, 20, 25, and 30 °C respectively. Potential applications in high‐conductivity transducers for humidity sensing and metal‐air batteries are demonstrated, achieving a maximum power output of 3.5 mW and an open‐circuit voltage of 1.25 V. The integration of digital material assembly of zinc, reliable high‐performance operation, and non‐toxicity pave the way for innovative advancements in sustainable electronics, including applications in environmental sensing, e‐textiles, and healthcare. [ABSTRACT FROM AUTHOR]

Research on chipless and passive architectures for environmental sensing is generating high interest because they do not require any semiconductor components or batteries to operate, thus resulting in an eco‐friendlier footprint. This study demonstrates a printed microstrip line with multiple resonators using biodegradable materials to continuously monitor temperature and relative humidity (RH). Constructed with a paper substrate and printed zinc conductive lines, and encapsulated with beeswax to protect against the interference of humidity, the microstrip line integrates spiral‐shaped resonators. One resonator operates at 1.2 GHz for temperature sensing, while another, coated with konjac glucomannan serves for relative humidity sensing at 2 GHz. The multi‐resonating features allow for a simultaneous assessment of temperature and humidity. The microstrip line displays a linear sensitivity to temperature of −1.35 MHz °C−1 and a non‐linear relative humidity sensitivity ranging between −0.8 and −8 MHz/%RH from 30% to 70% RH. Its degradation in a lab‐made compost for 70 days shows the removal of the transducing layer in 7 days and degradation of the cellulosic substrate starting after 5 weeks. The developed environmental sensing devices are notably promising for future applications in smart packaging and the tracking of goods aiming at the minimization of electronic waste. [ABSTRACT FROM AUTHOR]

Increasing environmental concerns raised by the accumulation of electronic waste draws attention to the development of sustainable materials for short‐lived electronics. In this framework, printed capacitive humidity sensors and temperature resistive detectors composed exclusively of biodegradable materials: shellac, carbon‐derived particles, and egg‐albumin are reported. The sensor platform comprises interdigitated electrodes serving as a capacitive transducer for humidity sensing, and a serpentine used as a resistive temperature detector. Both the interdigitated and serpentine electrodes are manufactured by screen‐printing carbon ink on a shellac substrate. The humidity sensors are constructed by drop‐coating egg albumin on the interdigitated carbon electrodes and the temperature detector is prepared by encapsulating the serpentine design with shellac. Shellac is shown to be a biodegradable alternative to hydrophilic cellulose‐derived substrates, with the capacitive humidity sensors demonstrating a sensitivity of 0.011% RH−1. The response and recovery times on shellac are 12 and 20 times faster than on cellulose‐based substrate, and the serpentine resistive temperature detectors have a temperature coefficient of 5300 ppm K−1. At the end of their service‐life, the sensors produced are home compostable and can be environmentally friendly disposed, potentially enabling their future use for sustainable and environmentally friendly smart‐packaging, agricultural sensing, or point‐of‐care testing. [ABSTRACT FROM AUTHOR]