Thus, the temperature in the EPCM remains constant at the selected melting temperature until the solid to liquid transition is complete. Once the CaO reaction has reached equilibrium, the energy stored as latent heat keeps the 5, 15-DPP two-phase EPCM at the target temperature until complete solidification. In our optimization work we observed that the purity of the CaO need not be high, although it should be consistent to yield consistent heat profiles. The ability to use less pure CaO is important for minimizing the cost per amplification, addressing the ����affordable���� aspect of the ASSURED guidelines. Other key physicochemical parameters of raw CaO that result from variation in kiln calcination of limestone also must be kept consistent for consistent heat profiles. However, we were able to produce precise heat profiles in our prototypes with commodity grades of CaO. This makes the only disposable materials in the device very inexpensive. The reaction of CaO and water can be tuned somewhat to control the steepness of the temperature ramp and the cDPCP maximum temperature for a given reaction chamber, although flexibility and precision is greatly improved by including the EPCM. The EPCM used here is tunable for many of its important characteristics making this device a flexible incubation platform potentially applicable to a number of isothermal amplification techniques. When evaluated by differential scanning calorimetry, the EPCM melts over a range of temperatures around the target, and displays some hysteresis in the phase change, presumably due to polydispersity in polymer chain length and supercooling of the EPCM. It is unclear at this time how this behavior contributes to variation seen in the results of the LAMP assay; however, the manufacturer of the EPCM is confident that further development of the EPCM for this application will mitigate this behavior. The EPCM is a fully hydrogenated fat product, so it is resistant to environmental oxidation and should be very stable. While the EPCM is not currently as readily available as CaO, and is not a commodity product like CaO, similar materials have been used in consumer products in the US. These EPCMs are made mainly from bio-based fats – namely beef tallow, palm oil, coconut oil and soybean oil �� so local, low-cost production of the EPCM in the developing world should be feasible. Portable energy for heat production could, of course, be supplied with conventional batteries, so a comparison seems appropriate.