# US 2013/0157271 A1 · Systems and Methods Using External Heater Systems in Microfluidic Devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0157271 A1 - Document ID: US20130157271A1 - Status: Published application - Kind: A1 - Application number: 13/474,523 - Filed: 2012-05-17 - Published: 2013-06-20 - Earliest claimed: 2011-05-17 - Assignees: Canon U.S. Life Sciences, Inc. - Inventors: Johnathan S. Coursey; Kenton C. Hasson - Web page: https://patentgrep.com/patent/US20130157271A1 ## CPC - H05B 1/0297: {Heating of fluids for non specified applications} - 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 7/52: {with provision for submitting samples to a predetermined sequence of different temperatures, e.g. for treating nucleic acid samples} - F25B 29/00: Combined heating and refrigeration systems, e.g. operating alternately or simultaneously - B01L 2200/147: Employing temperature sensors - B01L 2200/148: Specific details about calibrations - B01L 2300/0816: Cards, e.g. flat sample carriers usually with flow in two horizontal directions - B01L 2300/1827: using resistive heater - B01L 2300/1844: using fans - B01L 2300/1894: Cooling means; Cryo cooling - Y10T 436/143333: Saccharide [e.g., DNA, etc.] - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The present invention relates to methods and systems that result in high quality, reproducible, thermal melt analysis on a microfluidic platform. The present invention relates to methods and systems using thermal systems including heat spreading devices, including interconnection methods and materials developed to connect heat spreaders to microfluidic devices. The present invention also relates to methods and systems for controlling, measuring, and calibrating the thermal systems of the present invention. ## Claims ### Claim 1 A heating system for microfluidic devices comprising: a) a microfluidic device having one or more reservoirs or channels; b) a heat spreader, wherein the heat spreader is affixed to the microfluidic device such that the reservoirs or channels disposed on said microfluidic device are in thermal communication with the heat spreader; c) a heating means for heating the heat spreader; and, d) a measuring means for measuring one or more temperatures of the channels or reservoirs, wherein the measuring means comprises one or more temperature sensors. ### Claim 2 (depends on 1) The system of claim 1, wherein the measuring means comprises one or more temperature sensors selected from the group comprising temperature sensors embedded within the microfluidic device and temperature sensors external to the microfluidic device ### Claim 3 (depends on 2) The system of claim 2, wherein the one or more external sensors have a thermal capacitance that is matched to that of the temperature zone on the microfluidic device. ### Claim 4 (depends on 2) The system of claim 2, wherein the embedded sensors are passivated to prevent direct contact with samples in the one or more reservoirs or fluidic channels. ### Claim 5 (depends on 4) The system of claim 4, wherein the passivation materials comprise one or more of the following: glass, silicon dioxide, silicon nitride, silicon, polysilicon, parylene, polyimide, Kapton, or benzocyclobutene (BCB). ### Claim 6 (depends on 1) The system of claim 1, further comprising an external resistive heater. ### Claim 7 (depends on 1) The system of claim 1, further comprising (i) an external resistive heater and an external temperature sensor attached to the heat spreader and (ii) at least one embedded temperature sensor. ### Claim 8 (depends on 7) The system of claim 7, wherein the embedded temperature sensor is a resistance temperature detector (RTD). ### Claim 9 (depends on 8) The system of claim 8, wherein the at least one embedded RTD acts as both a temperature sensor and a heater. ### Claim 10 (depends on 7) The system of claim 7, wherein the at least one embedded temperature sensor and the heat spreader are located spatially apart on the microfluidic device. ### Claim 11 (depends on 7) The system of claim 7 wherein the at least one embedded temperature sensor is at least partially beneath the heat spreader. ### Claim 12 (depends on 1) The system of claim 1, wherein the heat spreader is symmetric in at least one direction. ### Claim 13 (depends on 1) The system of claim 1 wherein the heat spreader is made from an anisotropic thermally conductive material or from a composite including an anisotropic thermally conductive material. ### Claim 14 (depends on 1) The system of claim 1 wherein an anisotropic thermally conductive thermal interface material connects the heat spreader to the microfluidic device. ### Claim 15 (depends on 13) The system of claim 13, wherein the anisotropic thermally conductive materials are chosen from the group consisting of: graphite, graphene, diamonds of natural or synthetic origin, or carbon nanotubes (CNTs). ### Claim 16 (depends on 14) The system of claim 14, wherein the anisotropic thermally conductive materials are chosen from the group consisting of: graphite, graphene, diamonds of natural or synthetic origin, or carbon nanotubes (CNTs). ### Claim 17 (depends on 13) The system of claim 13, wherein the anisotropic thermally conductive material is configured such that its orientation exhibiting the highest thermal conductance is aligned with the orientation in which of the one or more reservoirs or channels are disposed on the microfluidic device. ### Claim 18 (depends on 14) The system of claim 14, wherein the anisotropic thermally conductive material is configured such that its orientation exhibiting the highest thermal conductance is aligned with the orientation in which of the one or more reservoirs or channels are disposed on the microfluidic device. ### Claim 19 (depends on 1) The system of claim 1 wherein the heat spreader includes one or more recesses for attachment of one or more sensors. ### Claim 20 (depends on 1) The system of claim 1 further comprising insulation over at least one temperature sensor located on the heat spreader. ### Claim 21 (depends on 1) The system of claim 1 wherein the heat spreader is affixed to the microfluidic device by applying high pressure. ### Claim 22 (depends on 21) The system of claim 21, wherein the high pressure is generated by pneumatics, spring assemblies, drive screws, or dead weight. ### Claim 23 (depends on 21) The system of claim 21 wherein the heat spreader is permanently affixed to the microfluidic device. ### Claim 24 (depends on 23) The system of claim 23 wherein the permanent bond is made with cyanoacrylate adhesive. ### Claim 25 (depends on 1) The system of claim 1 wherein the heat spreader is affixed to the microfluidic device using a material that includes nano or microparticles to increase the thermal conductance of the interconnection. ### Claim 26 (depends on 25) The system of claim 25 where the nano or microparticles are selected from the group comprising: silver, gold, aluminum and alloys thereof, copper and alloys thereof, zinc, tin, iron, CNTs, graphite, natural diamond, synthetic diamond, alumina, silica, titania, zinc oxide, tin oxide, iron oxide, and beryllium oxide. ### Claim 27 (depends on 1) The system of claim 1, further comprising a cooling means to adjust the temperature of the heat spreader or the one or more fluidic channels or reservoirs. ### Claim 28 (depends on 27) The system of claim 27, wherein the cooling means is configured to limit heat losses from samples present in the one or more fluidic channels or reservoirs. ### Claim 29 (depends on 27) The system of claim 27, wherein the cooling means improves uniformity of temperature in the temperature zone by limiting heat losses. ### Claim 30 (depends on 27) The system of claim 27, wherein the cooling means is a PWM fan or blower. ### Claim 31 (depends on 1) The system of claim 1 wherein nucleic acid melt analysis occurs on the microfluidic device. ### Claim 32 (depends on 31) The system of claim 31, wherein amplification of DNA occurs on the microfluidic device prior to nucleic acid melt analysis. ### Claim 33 (depends on 31) The system of claim 31 wherein the nucleic acid melt analysis determines the genotype of biological samples provided on the microfluidic device. ### Claim 34 A method of uniformly heating a microfluidic device comprising: a) providing a microfluidic device having one or more fluidic channels or reservoirs wherein the microfluidic device has a thermally conductive heat spreader in thermal contact with the microfluidic device; b) using a heating means to increase the temperature of the heat spreader to create a substantially uniform temperature zone on the microfluidic device; c) using a measuring means to determine the temperature of the heat spreader or the one or more fluidic channels or reservoirs. ### Claim 35 (depends on 34) The method of claim 34, wherein the measuring means comprises one or more temperature sensors selected from the group comprising temperature sensors embedded within the microfluidic device and temperature sensors external to the microfluidic device. ### Claim 36 (depends on 35) The method of claim 35, wherein the heat spreader includes one or more recesses for attachment of one or more temperature sensors. ### Claim 37 (depends on 35) The method of claim 35, further comprising insulation over at least one temperature sensor located on the heat spreader. ### Claim 38 (depends on 35) The method of claim 35, wherein the external temperature sensor is in contact with the microfluidic device or the heat spreader. ### Claim 39 (depends on 35) The method of claim 35, wherein the temperature sensor additionally controls the heating means. ### Claim 40 (depends on 34) The method of claim 34, wherein the microfluidic device further comprises an external resistive heater. ### Claim 41 (depends on 34) The method of claim 34, wherein the microfluidic device further comprises (i) an external resistive heater and an external temperature sensor attached to the heat spreader and (ii) at least one embedded temperature sensor. ### Claim 42 (depends on 41) The system of claim 41, wherein the embedded temperature sensor is a resistance temperature detector (RTD). ### Claim 43 (depends on 41) The method of claim 41, wherein the at least one embedded RTD acts as both a temperature sensor and a heater. ### Claim 44 (depends on 41) The method of claim 41, wherein the at least one embedded temperature sensor and the heat spreader are located spatially apart on the microfluidic device. ### Claim 45 (depends on 41) The method of claim 41 wherein the at least one embedded temperature sensor is at least partially beneath the heat spreader. ### Claim 46 (depends on 34) The method of claim 34, further comprising d) using a cooling means to adjust the temperature of the heat spreader or the one or more fluidic channels or reservoirs in response to the temperature measurements obtained in step c). ### Claim 47 (depends on 46) The method of claim 46, wherein the cooling means is configured to limit heat losses from samples present in the one or more fluidic channels or reservoirs. ### Claim 48 (depends on 46) The method of claim 46 wherein the cooling means improves uniformity of temperature in the temperature zone by limiting heat losses. ### Claim 49 (depends on 46) The method of claim 46 wherein the cooling means is a PWM fan or blower. ### Claim 50 (depends on 35) The method of claim 35 wherein the temperature sensor comprises at least one interchangeable external sensor attached to said heat spreader. ### Claim 51 (depends on 34) The method of claim 34, wherein the heat spreader is symmetric in at least one direction. ### Claim 52 (depends on 34) The method of claim 34, wherein the heat spreader is made from an anisotropic thermally conductive material or from a composite including an anisotropic thermally conductive material. ### Claim 53 (depends on 34) The method of claim 34, wherein an anisotropic thermally conductive thermal interface material connects the heat spreader to the microfluidic device. ### Claim 54 (depends on 52) The method of claim 52, wherein the anisotropic thermally conductive materials are chosen from the group consisting of: graphite, graphene, diamonds of natural or synthetic origin, or carbon nanotubes (CNTs). ### Claim 55 (depends on 53) The method of claim 53, wherein the anisotropic thermally conductive materials are chosen from the group consisting of: graphite, graphene, diamonds of natural or synthetic origin, or carbon nanotubes (CNTs). ### Claim 56 (depends on 52) The method of claim 52, wherein the anisotropic thermally conductive material is configured such that its orientation exhibiting the highest thermal conductance is aligned with the orientation in which of the one or more reservoirs or channels are disposed on the microfluidic device. ### Claim 57 (depends on 53) The method of claim 53, wherein the anisotropic thermally conductive material is configured such that its orientation exhibiting the highest thermal conductance is aligned with the orientation in which of the one or more reservoirs or channels are disposed on the microfluidic device. ### Claim 58 (depends on 34) The method of claim 34, wherein the heat spreader is affixed to the microfluidic device by applying high pressure. ### Claim 59 (depends on 25) The method of claim 25f, wherein the heat spreader is permanently affixed to the microfluidic device. ### Claim 60 (depends on 25) The method of claim 25g wherein the permanent bond is made with cyanoacrylate adhesive. ### Claim 61 (depends on 34) The method of claim 34, wherein the heat spreader is affixed to the microfluidic device using a material that includes nano or microparticles to increase the thermal conductance of the interconnection. ### Claim 62 (depends on 61) The method of claim 61, where the nano or microparticles are selected from the group comprising: silver, gold, aluminum and alloys thereof, copper and alloys thereof, zinc, tin, iron, CNTs, graphite, natural diamond, synthetic diamond, alumina, silica, titania, zinc oxide, tin oxide, iron oxide, and beryllium oxide. ### Claim 63 (depends on 34) The method of claim 34, additionally comprising calibrating the heating means or temperature sensor, wherein calibrating the heating means or temperature sensor comprises analyzing temperature data from at least one sensor in contact with the heat spreader and adjusting the heating means if necessary and/or calculating an offset for the sensor. ### Claim 64 (depends on 63) The method of claim 63 wherein calibrating the heating means comprises analyzing data from one or more sensor elements embedded on the microfluidic device to monitor the dynamic response of a temperature sensor that is external to the microfluidic device while being in thermal communication with the microfluidic device. ### Claim 65 (depends on 35) The method of claim 35 wherein the one or more external sensors have a thermal capacitance that is matched to that of the temperature zone on the microfluidic device. ### Claim 66 (depends on 34) The method of claim 34, wherein the heating comprises increasing the temperature of the heat spreader from a first temperature to a second temperature, such that any nucleic acid containing samples in the one or more fluidic channels or reservoirs are subjected to nucleic acid melt analysis. ### Claim 67 (depends on 66) The method of claim 66, wherein any nucleic acids present in a sample is subjected to nucleic acid amplification on the microfluidic device prior to melt analysis. ### Claim 68 (depends on 66) The method of claim 66, wherein the nucleic acid melt analysis determines the genotype of the samples. ### Claim 69 (depends on 63) The method of claim 63 wherein calibrating the heating means or temperature sensor further includes introducing a control sample having a known thermal characteristics into one or more fluidic channels or reservoirs. ### Claim 70 (depends on 69) The method of claim 69, wherein the known thermal characteristic is a melting temperature for a nucleic acid and wherein the control sample comprises one or more of wild type DNA, amplicon, oligonucleotide, or a mixture thereof. ### Claim 71 (depends on 70) The method of claim 70, wherein the control sample comprises an ultra-conserved element (UCE). ### Claim 72 (depends on 69) The method of claim 69, wherein the control sample is introduced into one or more fluidic channels or reservoirs that are in the same uniform temperature zone as one or more fluidic channels or reservoirs that contain an unknown sample. ### Claim 73 (depends on 35) The method of claim 35, wherein the one or more embedded temperature sensors is located underneath the reservoirs or fluidic channels on the microfluidic device. ### Claim 74 (depends on 35) The method of claim 35, wherein the embedded sensors are passivated to prevent direct contact with samples in the one or more reservoirs or fluidic channels. ### Claim 75 (depends on 74) The method of claim 74, wherein the passivation materials comprise one or more of the following: glass, silicon dioxide, silicon nitride, silicon, polysilicon, parylene, polyimide, Kapton, or benzocyclobutene (BCB). ### Claim 76 A method of calibrating heating means on a microfluidic device, comprising: a) providing a microfluidic device comprising: i. one or more microfluidic channels; ii. heating means in thermal communication with the microfluidic device, wherein the heating means comprises a heat spreader affixed to the microfluidic device and one or more temperature sensors in thermal communication with the heat spreader; iii. means for moving fluid through the microfluidic channels; and iv. temperature measuring means; b) introducing a control sample with known thermal properties into one or more microfluidic channels; c) causing the control sample to move into the microfluidic channel; d) causing the heating means to gradually increase the temperature of the microfluidic channel; e) monitoring the control sample for optical signals with an optical detection system and or monitoring temperature data from at least one sensor in contact with the heat spreader; f) analyzing the temperature data with a system controller to determine whether a smooth heating profile exists, and; g) adjusting the heating means if necessary to obtain a smooth heating profile. ### Claim 77 (depends on 76) The method of claim 76, wherein the control sample comprises one or more of: wild type DNA, amplicon, oligonucleotide, or a mixture thereof. ### Claim 78 (depends on 77) The method of claim 77, wherein the control sample comprises an ultra-conserved element (UCE). ### Claim 79 (depends on 77) The method of claim 77, wherein the known thermal property is the melting temperature of the nucleic acid. ### Claim 80 (depends on 76) The method of claim 76, wherein the microfluidic device further comprises an external resistive heater. ### Claim 81 (depends on 76) The method of claim 76, wherein the microfluidic device further comprises (i) an external resistive heater and an external temperature sensor attached to the heat spreader and (ii) at least one embedded temperature sensor. ### Claim 82 (depends on 81) The method of claim 81, wherein the at least one embedded temperature sensor is a resistance temperature detector (RTD). ### Claim 83 (depends on 81) The method of claim 81, wherein the at least one embedded RTD acts as both a temperature sensor and a heater. ### Claim 84 (depends on 81) The method of claim 81, wherein the at least one embedded RTD and the heat spreader are located spatially apart on the microfluidic device. ### Claim 85 (depends on 81) The method of claim 81 wherein the at least one embedded RTD is at least partially beneath the heat spreader. ### Claim 86 A method of performing nucleic acid melt analysis on a microfluidic device, comprising: a) providing a microfluidic device comprising: i. one or more microfluidic channels; ii. heating means in thermal communication with the microfluidic device, wherein the heating means comprises a heat spreader affixed to the microfluidic device, an external heater, and one or more temperature sensors in thermal communication with the heat spreader; iii. means for moving fluid through the microfluidic channels; and iv. temperature measuring means; b) introducing a biological sample into the microfluidic channel; c) causing the sample to move into the microfluidic channel; d) causing the heating means to gradually increase the temperature of the microfluidic channel; e) monitoring the sample for optical signals with an optical detection system; f) analyzing the detected optical signals with a controller to determine the melting temperature of the sample. ### Claim 87 (depends on 86) The method of claim 86, wherein the sample undergoes nucleic acid amplification in the microfluidic device prior to the nucleic acid melt analysis. ### Claim 88 (depends on 86) The method of claim 86, wherein analyzing the detected optical signals comprises preparing melting temperature plots. ### Claim 89 (depends on 86) The method of claim 86, wherein the optical signal is a fluorescence signal. ### Claim 90 (depends on 86) The method of claim 86, wherein the microfluidic device further comprises at least one embedded resistance temperature detector (RTD). ### Claim 91 (depends on 90) The method of claim 90, wherein the at least one embedded RTD acts as both a temperature sensor and a heater. ### Claim 92 (depends on 90) The method of claim 90, wherein the at least one RTD and the heat spreader are located spatially apart on the microfluidic device. ### Claim 93 (depends on 90) The method of claim 90 wherein the at least one RTD is at least partially beneath the heat spreader. ### Claim 94 A microfluidic system comprising: a microfluidic device comprising one or more microfluidic channels; heating means in thermal communication with the microfluidic device, wherein the heating means comprises a heat spreader affixed to the microfluidic device, an external resistive heater and one or more temperature sensors, all in thermal communication with the heat spreader; means for moving fluid through the microfluidic channels; temperature measuring means; an optical detection system; and analysis means. ### Claim 95 (depends on 1) The system of claim 1, wherein the heating means is selected from the group consisting of: peltier devices, contact with a hot gas or fluid, photon beams, lasers, infrared radiation, and other forms of electro-magnetic radiation.