"Flexible substrates" refers to materials that are capable of bending, stretching, or flexing without breaking or losing their structural integrity. Full definition
The laminator contains a highly sensitive web tension control system that is suitable for extremely low tolerances for a range of flexible substrates of different materials and varying thickness. (packaging-gateway.com)
Other research efforts into e-paper have involved using organic transistors embedded into flexible substrates, [33][34] including attempts to build them into conventional paper. (en.wikipedia.org)
Dr. Val Marinov's team has developed a method to embed ultra-thin, ultra-small RFID chips on paper or other flexible substrates, which could lead to ways to reduce counterfeiting of a wide variety of items such as pharmaceuticals, currency, legal papers, bearer bonds and other security documents. (sciencedaily.com)