In an example implementation, a reagent storage system for a microfluidic device includes a microfluidic chamber formed in a microfluidic device. A blister pack to store a reagent includes an electrically conductive membrane barrier adjacent to the chamber. A thinned region is formed in the membrane barrier, and a conductive trace is to supply electric current to heat and melt the thinned region. Melting the thinned region is to cause the membrane barrier to open and release the reagent into the chamber.