Carbon and shellac inks are cheaper, faster drying, heat and moisture resistant, metal-free, non-toxic, biodegradable, and easily formable

https://techxplore.com/news/2021-12-shellac-circuits.html

"tests for tensile strength, stability under water and other properties showed promising results utilizing patented applications... sensors for deformations, thin PET strips with printed ink structure whose electrical resistance changed precisely with varying degrees of bending... in sustainable printed electronics for conductive tracks and sensor elements in smart packaging and biomedical devices or in the field of food and environmental sensing"

Related: Eco-friendly conductive ink promises to revolutionize the production of soft stretchable electronic circuits

https://techxplore.com/news/2023-09-eco-friendly-ink-revolutionize-production-soft.html