Explainer: what is thermal paper?

Thermal paper is widely used for things like receipts and tickets. But to make text appear without using ink, some of these materials rely on toxic chemicals that many countries are starting to phase out. Because of this, scientists are now developing alternatives – for example, a team at École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland recently developed a biomass-derived thermal paper that has a much lower toxicity. ¹