Ecoresorbable chipless temperature-responsive tag made from biodegradable materials for sustainable IoT

TL;DR

Researchers created a compostable, wireless temperature tag using biodegradable materials that can track temperature changes and break down after use, supporting sustainable IoT applications.

Contribution

A fully ecoresorbable, chipless, and wireless temperature-responsive tag using biodegradable materials and bio-based phase-change materials is introduced.

Findings

The tag uses bio-based phase-changing materials to induce irreversible resonance frequency shifts at specific melting points.

The device disintegrates in a compost environment within 9 weeks after service life.

Printed zinc metallic traces encapsulated with beeswax enable wireless operation and prevent oxidation.

Abstract

Temperature monitoring within the cold chain, essential for safety of perishable products, typically employs devices such as battery-powered data loggers and radio-frequency identification tags. Such devices include non-eco-friendly components, posing challenges for their safe disposal and recycling. This study demonstrates the fabrication of a fully ecoresorbable, chipless, and wireless temperature-responsive tag, designed to irreversibly track temperature changes through a permanent shift in resonance frequency. The tag is printed on a customized moisture-resistant poly(β-hydroxybutyrate)-cellulose composite substrate. An RLC circuit made of printed zinc metallic traces, encapsulated with beeswax to prevent oxidation, enables seamless wireless operation. The tag utilizes bio-based phase-changing materials such as frozen olive, jojoba, and coconut oils to induce irreversible resonance frequency shifts of more than 30 MHz at respective melting points of 8 °C, 15 °C, and 25 °C. A cellulose capillary element efficiently absorbs the melted oil, enabling reliable operation at inclinations from 0° to 90°. At the end of its service life, the device can undergo disintegration in a compost environment within 9 weeks. This work demonstrates a sustainable chipless technology from material selection and manufacturing processes to end-of-life disposal as an advanced thermal indicator solution for cold chain temperature-excursion detection.

The authors demonstrate a chipless and wireless temperature tag using a biopolymer and printed zinc. Bio-based phase-change materials enable irreversible thermal detection, and the device fully disintegrates in compost, supporting transient electronics.

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