Nature Sustainability, Published online: 19 June 2026; doi:10.1038/s41893-026-01870-3 The growing market for soft electronics largely relies on fossil fuel-based polymer substrates. This work points towards a more sustainable future for the field by presenting a bio-based substrate for metal-on-polymer soft sensors that are degradable, recyclable, interfacially robust, mechanically tough and self-reparable.