This abstract describes for the first time the use of alginate hydrogels as miniaturised valves in microfluidic devices. These biocompatible and biodegradable microvalves are in-situ generated, on demand, allowing for microfluidic flow control. The microfluidic devices were fabricated using the origami technique with seven layers of cyclic olefin copolymer (COP) and thermocompression bonding. They can be thermally actuated (ON/OFF) at mild temperatures, 37 °C, and chemically erased from the main channel using an ethylenediaminetetraacetic acid disodium salt dehydrated (EDTA) solution, ensuring the reusability of the whole device.