TY - JOUR T1 - Multi-stage chemical heating for instrument-free biosensing JF - bioRxiv DO - 10.1101/367029 SP - 367029 AU - John P. Goertz AU - Kenya M. Colvin AU - Andrew B. Lippe AU - John L. Daristotle AU - Peter Kofinas AU - Ian M. White Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/07/11/367029.abstract N2 - Improving the portability of diagnostic medicine is crucial to alleviating global access-to-care deficiencies. This requires not only designing devices that are small and lightweight but also autonomous and independent of electricity. Here, we present a strategy for conducting automated multi-step diagnostic assays using chemically generated, passively regulated heat. Ligation and polymerization reagents for Rolling Circle Amplification of nucleic acids are separated by melt-able phase-change partitions, thus replacing precise manual reagent additions with automated partition melting. To actuate these barriers and individually initiate the various steps of the reaction, field ration heaters exothermically generate heat in a thermos while fatty acids embedded in a carbonaceous matrix passively buffer the temperature around their melting points. Achieving multi-stage temperature profiles extends the capability of instrument-free diagnostic devices and improves the portability of reaction automation systems built around phase-change partitions. ER -