Thermal control device and methods of use
Thermal control devices adapted to provide improved control and efficiency in temperature cycling are provided herein. Such thermal control device can include a thermoelectric cooler controlled in coordination with another thermal manipulation device to control an opposing face of the thermoelectric cooler and/or a microenvironment. Some such thermal control devices include a first and second thermoelectric cooler separated by a thermal capacitor. The thermal control devices can be configured in a planar configuration with a means for thermally coupling with a planar reaction vessel of a sample analyzer for use in thermal cycling in a polymerase chain reaction of the fluid sample in the reaction vessel. Methods of thermal cycling using such a thermal control devices are also provided.
1. A thermal control device comprising:
a first thermoelectric cooler having an active face and a reference face;
a second thermoelectric cooler having an active face and a reference face;
a thermal capacitor disposed between the first and second thermoelectric coolers such that the reference face of the first thermoelectric cooler is thermally coupled with the active face of the second thermoelectric cooler through the thermal capacitor, wherein the thermal capacitor is formed of a layer of thermally conductive material with a higher thermal conductivity than that of the active faces and reference faces of the first and second thermoelectric coolers;
a first temperature sensor configured to sense a first temperature of the active face of the first thermoelectric cooler;
a second temperature sensor configured to sense a second temperature of the thermal capacitor; and
a controller operatively coupled to each of the first and second thermoelectric coolers, wherein the controller is configured to operate the second thermoelectric cooler concurrent with the first thermoelectric cooler so as to increase efficiency of the first thermoelectric cooler as a temperature of the active face of the first thermoelectric cooler is heated or cooled from an initial temperature to a target temperature, wherein the first and second temperature sensors are coupled to the controller such that operation of the first and second thermoelectric coolers is based, at least in part, on inputs from the first temperature sensor and the second temperature sensor,
wherein the controller is configured to operate the first thermoelectric cooler according to a primary control loop into which the input of the first temperature sensor is provided, and configured to operate the second thermoelectric cooler according to a secondary control loop into which the input of the second temperature sensor is provided,
wherein the primary control loop is configured to cycle between a heating mode of the first thermoelectric cooler in which the active face of the first thermoelectric cooler heats to an elevated target temperature relative to the initial temperature and a cooling mode of the first thermoelectric cooler in which the active face of the first thermoelectric cooler is cooled to a reduced target temperature relative to the elevated target temperature, and concurrently the secondary control loop is configured to cycle between a heating mode and a cooling mode of the second thermoelectric cooler, and
wherein during the heating mode and the cooling mode of the second thermoelectric cooler, the secondary control loop leads or lags the primary control loop with respect to time such that the temperature of the thermal capacitor varies during the concurrent cycling of the first and second thermoelectric coolers so that the thermal capacitor facilitates controlled storage and release of thermal energy to improve speed and efficiency of thermal cycling of the active face of the first thermoelectric cooler.
2. The device of claim 1 , wherein the thermal capacitor is a layer of copper with a thickness of about 5 mm or less.
3. The device of claim 1 , wherein the thermal capacitor is a layer of copper with a thickness of about 1 mm or less.
4. The device of claim 1 , wherein the controller is configured such that a bandwidth response of the primary control loop is timed faster than a bandwidth response of the secondary control loop.
5. The device of claim 1 , wherein each of the primary and secondary control loops are closed-loop.
6. The device of claim 1 , wherein the controller is configured such that the secondary control loop switches the second thermoelectric cooler between heating and cooling modes before the first control loop is switched between heating and cooling so as to thermally load the thermal capacitor.
7. The device of claim 1 , wherein the secondary control loop maintains a temperature of the thermal capacitor within about 40° C. from the temperature of the active face of the first thermoelectric cooler.
8. The device of claim 1 , wherein the controller is configured such that efficiency of the first thermoelectric cooler is maintained by operation of the second thermoelectric cooler such that heating and cooling with the active face of the first thermoelectric cooler occurs at a ramp rate of within 10° C. per second or less.
9. The device of claim 1 , wherein the elevated target temperature is about 90° C. or greater and the reduced target temperature is about 40° C. or less.
10. The device of claim 1 , further comprising:
a heat sink coupled with the reference face of the second thermoelectric cooler configured to prevent thermal runaway during cycling.
11. The device of claim 10 wherein a thickness from the active face of the first thermoelectric cooler to an opposite facing side of the heat sink is 20 mm or less.
12. The device of claim 11 , wherein a planar size of the thermal control device comprises a length of 45 mm or less and a width of 20 mm or less.
13. The device of claim 11 , wherein a planar size of the device is defined by a length of about 40 mm by about 12.5 mm.
14. The device of claim 1 , wherein the active face of the first thermoelectric cooler is about 11 mm by 13 mm.
15. The device of claim 14 , wherein the thermal controll device is adapted to engage with a reaction vessel for thermal cycling of the reaction vessel on a single side thereof to allow optical detection of a target analyte from an opposing side of the reaction vessel.
16. A thermal management system comprising:
two or more thermal control devices, each as in claim 1 ; and
a fixture adapted to alternatingly position the two or more thermal control devices at an active location for effecting heating and/or cooling cycling with the respective control device and to selectively alternate among the two or more thermal control devices.