# US 2014/0154786 A1 · Chemical Temperature Control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0154786 A1 - Document ID: US20140154786A1 - Status: Published application - Kind: A1 - Application number: 13/874,060 - Filed: 2013-04-30 - Published: 2014-06-05 - Earliest claimed: 2007-06-06 - Assignees: Program for Appropriate Technology In Health - Inventors: Paul Donald Labarre; Jay Lewis Gerlach; Bernhard Hans Weigl; Gonzalo Jose Domingo-Villegas - Web page: https://patentgrep.com/patent/US20140154786A1 ## CPC - C12Q 1/686: Polymerase chain reaction [PCR] - B01L 3/5027: {by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip} - B01L 3/50273: {characterised by the means or forces applied to move the fluids} - B01L 7/00: Heating or cooling apparatus (autoclaves B01J3/04); Heat insulating devices - B01L 7/525: {with physical movement of samples between temperature zones} - B01L 2300/0663: Whole sensors - B01L 2300/0816: Cards, e.g. flat sample carriers usually with flow in two horizontal directions - B01L 2300/088: Channel loops - B01L 2300/1855: using phase changes in a medium - B01L 2300/1877: using chemical reactions - B01L 2400/0406: capillary forces - B01L 2400/0442: thermal energy, e.g. vaporisation, bubble jet - B01L 2400/0445: Natural or forced convection - B01L 2400/0478: pistons - B01L 2400/0487: fluid pressure, pneumatics - C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES - B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE ## Abstract Exothermic and/or endothermic chemical reactions in combination with phase change materials can produce output temperature(s) within strict tolerances without requiring expensive and complicated external equipment to generate and maintain an output temperature. Similarly, an exothermic phase change material, which generates heat as a consequence of crystallizing a supercooled liquid, can generate heat at a constant temperature, without requiring expensive and complicated external equipment, as a consequence of the liquid form of the exothermic phase change material being in equilibrium with the solid form of the exothermic phase change material. Numerous biological and chemical processes and/or diagnostic devices require a constant temperature or temperatures for set periods of time. An example completely non-instrumented diagnostic platform based on nucleic acid amplification is described, which is particularly suited for use in developing countries that may not have access to expensive and complicated external equipment. ## Claims ### Claim 1 An assay platform, comprising: a zone requiring controlled temperature conditions; and a heating element thermally coupled to the zone requiring controlled temperature conditions, the heating element comprising: an exothermic chemical reagent mixture; and a phase change material; wherein the amount of phase change material is configured to provide a controlled, substantially constant temperature to the zone requiring controlled temperature conditions by at least a partial phase transition of the phase change material when heated by an exothermic chemical reaction generated by the exothermic chemical reagent mixture. ### Claim 2 (depends on 1) The assay platform of claim 1, wherein said exothermic chemical reagent mixture comprises iron powder and carbon powder. ### Claim 3 (depends on 1) The assay platform of claim 1, wherein said exothermic chemical reagent mixture comprises a reduction of copper with magnesium. ### Claim 4 (depends on 1) The assay platform of claim 1, wherein said exothermic chemical reagent mixture comprises calcium oxide hydration. ### Claim 5 (depends on 1) The assay platform of claim 1, wherein said phase change material comprises a paraffin. ### Claim 6 (depends on 1) The assay platform of claim 1, wherein said phase change material is selected from the group consisting of a metal, an inorganic compound, an inorganic eutectic and an organic compound. ### Claim 7 (depends on 1) The assay platform of claim 1, wherein said zone requiring controlled temperature conditions comprises a zone for conducting a biochemical reaction requiring a constant, elevated temperature. ### Claim 8 (depends on 7) The assay platform of claim 7, wherein said biochemical reaction is a nucleic acid amplification reaction. ### Claim 9 (depends on 8) The assay platform of claim 8, wherein said nucleic acid amplification reaction is an isothermal nucleic acid amplification. ### Claim 10 (depends on 7) The assay platform of claim 7, wherein said biochemical reaction is a reverse-transcription reaction. ### Claim 11 (depends on 1) The assay platform of claim 1, wherein said zone requiring controlled temperature conditions comprises a zone for a biological organism requiring incubation at elevated, constant temperature. ### Claim 12 (depends on 1) The assay platform of claim 1, wherein said heating element has a well-defined working temperature. ### Claim 13 (depends on 12) The assay platform of claim 12, wherein said well-defined working temperature is between about 53 to about 70 degrees C. ### Claim 14 (depends on 1) The assay platform of claim 1, wherein said heating element has a well-defined working duration, after which the temperature of the heating element drops back to ambient levels. ### Claim 15 (depends on 14) The assay platform of claim 14, wherein said well-defined working duration is approximately one hour. ### Claim 16 (depends on 1) The assay platform of claim 1, further comprising a second heating element, wherein said second heating element has a different working temperature or duration, resulting in an assay platform having multiple heating plateaus. ### Claim 17 (depends on 16) The assay platform of claim 16, wherein said platform generates two heating plateaus. ### Claim 18 (depends on 17) The assay platform of claim 17, wherein said platform generates a first heating plateau comprising a working temperature between about 92 to about 96 degrees C. for approximately 5 minutes, followed by a second heating plateau comprising a working temperature between about 53 to about 70 degrees C. for approximately 80 minutes. ### Claim 19 (depends on 1) The assay platform of claim 1, further comprising a density-driven closed-loop fluid circulation channel configured to achieve heat cycling in a circulation fluid as a function of the circulation fluid being heated as it passes through the heating element, and cooled when it is outside the heating element. ### Claim 20 (depends on 19) The assay platform of claim 19 wherein said heating element acts as a heat source and an area outside of said heating element acts as a heat sink; wherein said heat source is at a lower elevation than said heat sink; and wherein said closed-loop fluid circulation channel has a minimally tortuous fluid path. ### Claim 21 (depends on 17) The assay platform of claim 17, further comprising a chemical cooling element. ### Claim 22 (depends on 1) The assay platform of claim 1, further comprising a wicking-driven linear channel configured to achieve heat cycling in a circulation fluid as a function of the circulation fluid being heated as it passes repeatedly over the heating element and being cooled when it is outside the heating element. ### Claim 23 (depends on 1) The assay platform of claim 1, farther comprising a spring-loaded, syringe-like pump driven linear channel configured to achieve heat cycling in a circulation fluid as a function of the circulation fluid being heated as it passes repeatedly over the heating element and being cooled when it is outside the heating element. ### Claim at position 24 24-46. (canceled) ### Claim 47 (depends on 12) The assay platform of claim 12, wherein said well-defined working temperature is between about 37 to about 55 degrees C. ### Claim 48 (depends on 1) The assay platform of claim 1, wherein said phase change material transitions from a liquid to a gas when heated by said exothermic chemical reaction. ### Claim 49 (depends on 1) The assay platform of claim 1, wherein said phase change material transitions from a solid to a liquid when heated by said exothermic chemical reaction. ### Claim 50 (depends on 1) The assay platform of claim 1, wherein said heating element is in one layer. ### Claim 51 (depends on 1) The assay platform of claim 1, wherein said heating element is in two layers. ### Claim 52 (depends on 51) The assay platform of claim 51, wherein said phase change material is disposed between the zone requiring controlled temperature conditions and the exothermic chemical reagent mixture. ### Claim 53 (depends on 1) The assay platform of claim 1, wherein said phase change material is carbohydrate encapsulated. ### Claim 54 (depends on 53) The assay platform of claim 53, wherein said phase change material is encapsulated in carbohydrate spheres. ### Claim 55 (depends on 1) The assay platform of claim 1, wherein said heating mixture is configured to maintain a constant temperature without using an electrical power source. ### Claim 56 (depends on 1) The assay platform of claim 1, wherein said exothermic chemical reagent mixture comprises magnesium.