EPFL develops biodegradable chipless smart sensor for shipments monitoring

Researchers from EPFL, Empa, and CSEM have developed a fully compostable, wireless, chipless printed smart sensor tag for monitoring temperature-sensitive shipments.

• Main announcement/action: The teams (EPFL LMTS, Empa, CSEM) report a silicon-free, battery-free, chipless smart tag produced in a four-year project (GREENsPACK) that detects if a shipment exceeded a temperature threshold via an irreversible change in resonance; the device is biodegradable/compostable, printed on a biopolymer + cellulose fiber substrate, uses highly conductive zinc tracks protected by natural wax, and relies on bio-based oils (frozen olive, jojoba, coconut) that melt at different temperatures to set thresholds. The project was funded by the Swiss National Science Foundation (SNSF) and Innosuisse under the BRIDGE Discovery program.
• Background and technical details: Readout technology was developed at CSEM and the substrate at Empa; the tag requires no battery or silicon chip and functions via a wireless electrical resonator whose frequency shifts irreversibly when oil melts and is absorbed by a cellulosic layer (ensuring reliability at different inclination angles). The work is published in Nature Communications (2025) (Bourely et al., DOI: 10.1038/s41467-025-65458-9). The article cites e-waste data: 62 megatons in 2022 with 22% properly recycled.