Floating thermal contact enabled PCR
The present invention generally pertains to a system which utilizes floating thermal contact to enable PCR, in a thermal management device. Comprised of multiple thermal zones attached to a framework, each zone an individually actuated, isolated sub-assembly. The actuation of each zone ensures physical contact with an uneven, yet flat microfluidic chip to achieve effective, conductive heat transfer. The isolation of each zone serves to insulate the thermal zones from each other and minimize undesired heat transfer between adjacent zones, so that each zone is at a proper, uniform temperature.
1. A method to perform PCR reactions in a microfluidic device comprising:
providing a thermal management device comprising a framework wherein:
a plurality of thermal zone sub-assemblies, each having a thermal control element configured to flex a respective thermal zone sub-assembly by a distance of about 0.75 mm to about 1.0 mm relative to the other thermal zone sub-assemblies, wherein each thermal zone sub-assembly has a minimal spacing of 1 mm between itself and any other thermal zone sub-assembly or the framework;
a plurality of thermal spreaders, each configured to come into contact with one or more of the thermal control elements;
a plurality of thermal actuation mechanisms, each configured to move one of more of the thermal control elements into contact with one or more of the plurality of thermal spreaders; and
one or more microfluidic channels aligned to pass over the plurality of thermal zone sub-assemblies;
loading the one or more microfluidic channels of the microfluidic device with a plurality of droplets that contain reagents necessary for desired PCR reactions; and
performing PCR in the microfluidic device.
2. The method of claim 1 , wherein each thermal zone sub-assembly is coupled to a framework by the one or more thermal actuation mechanisms, and wherein the thermal actuation mechanisms comprise insulative bearings, fasteners, and a spring, the spring being arranged to apply a force to drive one or more of the thermal control elements toward one of the one or more thermal spreaders.
3. The method of claim 2 , wherein the insulative bearings are polymer-based bearings and wherein each fastener is a shoulder screw.
4. The method of claim 1 , wherein each of the thermal actuation mechanisms of the thermal management device further comprises a first insulative fiber washer around a shoulder screw that holds the spring in place.
5. The method of claim 1 , wherein each thermal control element can be configured to have an operational temperature of from about 22° C. to about 95° C.
6. The method of claim 1 , further comprising:
maintaining at least one thermal zone sub-assembly at a temperature above room temperature; and
maintaining at least one thermal zone sub-assembly at a temperature at or below room temperature.
7. The method of claim 6 , wherein the thermal management device further comprises a resistive heating element configured to maintain at least one thermal zone sub-assembly at a temperature above room temperature.
8. The method of claim 6 , wherein the thermal management device further comprises a thermoelectric element configured to maintain at least one thermal zone sub-assembly at a temperature at or below room temperature.
9. The method of claim 6 , wherein a first thermal zone and a fifth thermal zone are maintained at a temperature at or below room temperature, wherein a second thermal zone, fourth thermal zone, and a sixth thermal zone are maintained at a temperature above room temperature, and wherein a third thermal zone is maintained at a temperature above the temperature of at least the second thermal zone.
10. The method of claim 1 , wherein a flexible heater circuit is configured and arranged to be the thermal control element for two or more thermal zone sub-assemblies of the thermal management device.
11. The method of claim 10 , further comprising moving a first region of the flexible heater circuit with one of the thermal actuation mechanisms to be in contact with one of the thermal spreaders.
12. The method of claim 11 , further comprising moving a second region of the flexible heater circuit with one of the thermal actuation mechanisms to be in contact with another one of the thermal spreaders.
13. The method of claim 1 , wherein the one or more microfluidic channels each have a first channel section for passing the droplets that contain reagents necessary for desired PCR reactions over a subset of the thermal zone sub-assemblies, further comprising routing the droplets alternatingly over a primary extension zone and a denature zone, and then routing the droplets alternatingly over a secondary extension zone and the denature zone.
14. The method of claim 13 , wherein the primary extension zone is set at a temperature of about 65° C., the denature zone is set at a temperature of about 95° C., and the secondary thermal zone is set at a temperature of about 55° C.
15. The method of claim 13 , wherein the denature zone is set at a temperature of about 98° C.
16. The method of claim 13 , wherein the secondary thermal zone is set at a temperature of about 51° C.
17. The method of claim 13 , wherein the one or more microfluidic channels each have a second channel section for passing the droplets that contain reagents necessary for desired PCR reactions over a subset of the thermal zone sub-assemblies, further comprising routing the droplets over a sequencing incubation zone, and then routing the droplets over the primary extension zone.
18. The method of claim 17 , wherein the sequencing incubation zone is set at a temperature of about 34° C.
19. The method of claim 17 , wherein the sequencing incubation zone is set at a temperature of about 35° C.