WO2020154407A1

WO2020154407A1 - Rapid temperature control unit

Info

Publication number: WO2020154407A1
Application number: PCT/US2020/014619
Authority: WO
Inventors: Makoto Ogusu; Maxwell HENSLEY; Raymond Dawson; Ralph C. MCCANN III; Hanyoup Kim
Original assignee: Canon Virginia, Inc.
Priority date: 2019-01-23
Filing date: 2020-01-22
Publication date: 2020-07-30

Abstract

A thermal cycler comprises a flat sample container; a thin film heater, wherein the thin film heater is located on a side of the flat sample container; a thermo-electric cooler located adjacent to the thin film heater; a heat sink located adjacent to the thermo-electric cooler; and a thermal insulator, wherein the thermal insulator is located on a side of the flat sample container opposite the thin film heater, the thermo-electric cooler, and the heat sink.

Description

TITLE

RAPID TEMPERATURE CONTROL UNIT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 62/795,803, which was filed on January 23, 2019.

BACKGROUND

[0002] Technical Field: The present disclosure relates to polymerase chain reaction (PCR) for DNA amplification.

[0003] Background: PCR is a technique to amplify DNA or RNA to detect a target pattern. PCR needs to control sample temperatures at specific states of temperature. The overall duration time of the PCR process depends on how quickly thermal cycling can be performed, so a rapid thermal control system is preferable.

[0004] In general, a sample-well thermal cycler has a thermo-electric cooler (TEC) to control the temperature. A conventional sample-well-shaped aluminum block sits on the TEC. The sample well can fit closely to the aluminum block so that heat is transferred more efficiently from the aluminum block to the sample that is in each well of the well plate.

[0005] Other techniques include putting a heater underneath a micro channel to control a sample liquid temperature as quickly as possible. US9,061 ,278 discusses a glass chip with micro-fluidic channels with heaters underneath the micro channels. The short distance between the heater and the micro channel enables fast heat transfer.

But, while US9,061 ,278 provides quick PCR DNA amplification, the cost of

consumables is very high. [0006] In another technique, multiple styles of heater types are used in one unit. US2011/0081136A1 discusses an infrared (IR) heater for heating and the TEC for cooling, where each thermo controller can focus on its strengths. The first heating method maintains at least the first target temperature, and the second heating method maintains the second and the third temperatures. But each heater just focuses on each specialty, and it does not provide a functionality of the combination of heaters. And because nothing can be positioned between the IR light and a cartridge, the thermo electric heater touches only the bottom of the cartridge.

[0007] In still yet another technique, two different heating methods are used.

US2007/0113880 discusses using a thin film heater and a thermo-electric cooler to maintain sample-well-plate temperature. The thermo-electric cooler has the primary temperature control role. The thin film heater, which is put at the periphery of the sample-well-plate heater block, makes the well-plate temperature more uniform. In US2007/0113880, the thermal cycling speed depends only on the speed of the thermo electric cooler. The thermo-electric cooler is a device which is able to actively both elevate and decrease the temperature. But the thermo-electric cooler is not the fastest heating device.

SUMMARY

[0008] Some embodiments of a thermal cycler comprise a flat sample container; a thin film heater, wherein the thin film heater is located on a side of the flat sample container; a thermo-electric cooler located adjacent to the thin film heater; a heat sink located adjacent to the thermo-electric cooler; and a thermal insulator, wherein the thermal insulator is located on a side of the flat sample container opposite the thin film heater, the thermo-electric cooler, and the heat sink.

[0009] Some embodiments of a thermal cycler comprises a planar-shaped sample container; a thin film heater, wherein the thin film heater is located on a side of the planar-shaped sample container; a thermo-electric cooler located adjacent to the thin film heater; a moving mechanism that is configured to move the thermo-electric cooler; a heat sink located adjacent to the thermo-electric cooler; and a thermal insulator, wherein the thermal insulator is located on a side of the planar-shaped sample container opposite the thin film heater, the thermo-electric cooler, and the heat sink.

[0010] Some embodiments of a thermal cycler comprise a planar-shaped sample container that has a first side and a second side; a thin film heater that has a first side and a second side, wherein the second side of the thin film heater contacts the first side of the planar-shaped sample container; a thermo-electric cooler that has a first side and a second side, wherein, of the first side and the second side of the thermo-electric cooler, the second side is closest to the thin film heater; a cold sink, wherein the cold sink contacts the second side of the thermo-electric cooler; a heat sink located adjacent to the first side of the thermo-electric cooler; and a thermal insulator, wherein the thermal insulator is located on the second side of the planar-shaped sample container.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1A illustrates an example embodiment of a thermal cycler.

[0012] FIG. 1 B illustrates an exploded view of the example embodiment of a thermal cycler in FIG. 1A.

[0013] FIG. 2 shows an example embodiment of a temperature profile and a power- supply timing chart.

[0014] FIG. 3A illustrates an example embodiment of a thermal cycler.

[0015] FIG. 3B illustrates an exploded view of the example embodiment of a thermal cycler in FIG. 3A.

[0016] FIG. 4 illustrates a comparison of the temperature profiles of the thermal cycler in FIGs. 1A-B and the thermal cycler in FIGs. 3A-B.

[0017] FIG. 5A illustrates an exploded, partially sectional view of an example embodiment of a thermal cycler.

[0018] FIG. 5B illustrates an example embodiment of a thermal cycler.

[0019] FIGs. 6A-B illustrate an example embodiment of a thermal cycler.

[0020] FIG. 7A-C illustrate an example embodiment of a thermal-cycler shuttle. [0021] FIG. 8 illustrates a plot of a sample-container temperature versus time for a portion of the full PCR cycling time for one embodiment of a thermal-cycler shuttle.

[0022] FIG. 9A-B illustrate an example embodiment of a thermal-cycler shuttle.

DESCRIPTION

[0023] The following paragraphs describe certain explanatory embodiments. Other embodiments may include alternatives, equivalents, and modifications. Additionally, the explanatory embodiments may include several features, and a particular feature may not be essential to some embodiments of the devices, systems, and methods that are described herein.

[0024] Some embodiments of the present disclosure provide a cost-effective, rapid thermal cycler that includes a thermo-electric cooler (TEC) that is stacked along with a thin film heater with the sample liquid container, and a thermal insulator that is located at the opposite side.

[0025] FIG. 1A illustrates an example embodiment of a thermal cycler 100, and FIG.

1 B illustrates an exploded view of the example embodiment of a thermal cycler 100 in FIG. 1A. The thermal cycler 100 includes a heat sink 105, a TEC 110, a heater 115 (e.g., a thin film heater), a sample container 120, and a thermal insulator 125. Two power-supply lines 111 are connected to the TEC 110, and two power-supply lines are connected to the heater 115. The operation of the TEC 110 and the operation of the heater 115 can be adjusted by adjusting the power that is supplied by their respective supply lines, for example by adjusting the voltage of the power-supply lines.

[0026] When elevating the temperature, a reduction of the heat mass makes the thermal cycle quicker and more energy efficient. In the example embodiment of FIG. 1 , the heat mass (the total mass of the thermal cycler 100 that is heated during thermal cycling) is reduced by making the heater 115 and the sample container 120 the same shape and by making the heat mass flat to reduce the additional heat transfer material. Also, the rapid thermal cycling is furthered, in part, by putting the heater 115 as close as possible to the sample liquid, which is in the sample container 120. [0027] To improve the heat-consumption efficiency, thermal isolation is helpful. In some embodiments, the thermal cycler 100 maintains the heat in the heating phase and releases the heat to quickly cool down the sample container 120 in the cooling phase.

[0028] Thus, in some embodiments, the TEC 110 acts as a heat valve that is in a closed state during the heating phase and that is in an open state during the cooling phase. FIG. 2 shows an example embodiment of a temperature profile and a power- supply timing chart. The heater-side surface of the TEC 110 is heated when the heater 115 generates heat. At this phase, there is minimum heat transfer between the TEC 110 and the heater 115 because the temperature of the bottom of the TEC 110 becomes the same as the temperature of the heater 115. The heat generated by the heater 115 cannot leak well through the TEC 110 and the thermal insulator 125, so the generated heat is efficiently consumed to rapidly elevate temperature of the sample container 120.

[0029] Heat transfer between two objects (e.g., the TEC 110 and the heater 115) that are the same temperature is less than the heat transfer through the thermal insulator 125. Thus, blocking heat transfer at the side of the heater 115 opposite to the sample container 120 increases the speed at which the heater 115 can increase the

temperature of the sample container 120. And, in a two-heater system (the heater 115 and the TEC 110), blocking heat transfer at the side of the heater 115 opposite to the sample container 120 affects how efficiently the generated heat increases the

temperature of the sample container 120.

[0030] As the heater 115 is turned off, the polarity of the power to the TEC 110 is reversed, and the TEC 110 conveys the heat from the heater 115 to the heat sink 105.

In this phase, the TEC 110 is working but not the heater 115, and the TEC 110 is working to remove the heat from the sample container 120 through the heater 115. The heater 115 has less heat mass, so the heat stored in the sample container 120 is efficiently conveyed to the heat sink 105 by the TEC 110. In terms of cooling efficiency, the TEC 110 may be more efficient if the TEC 110 directly touches the sample container 120. [0031] FIG. 3A illustrates an example embodiment of a thermal cycler 100, and FIG. 3B illustrates an exploded view of the example embodiment of a thermal cycler 100 in FIG. 3A. The thermal cycler 100 has a thin film heater 115 above a sample container 120 and has thermal insulators 125 that surround the heater 115 and the sample container 120. Two power-supply lines are connected to the heater 115.

[0032] FIG. 4 illustrates a comparison of the temperature profiles the thermal cycler in FIGs. 1A-B and the thermal cycler in FIGs. 3A-B. In this comparison, the temperatures were measured at the bottom of a plastic plate that was approximately 0.2 mm thick and that mimicked a sample container. The sensor is not described in FIG. 4. According to this result, the TEC 110 does not release heat the same way the thermal insulator 125 does, and the TEC 110 can remove the heat very efficiently once the supplied voltage polarities of the TEC’s power supply lines 116 are reversed.

[0033] FIG. 5A illustrates an exploded, partially sectional view of an example embodiment of a thermal cycler 100. This embodiment has an air-type thermal insulator 126 instead of a thermal insulator material. FIG. 5A illustrates a sectional view of the air-type thermal insulator 126. The air-type thermal insulator 126 has small pockets so that the contact area between the sample container 120 and the air-type thermal insulator 126 is very small. The air-type thermal insulator 126 may further restrict the heat flux from the sample container 120 to the thermal insulator 126. And small air pockets are good thermal insulators because they can prevent or reduce air convection.

[0034] FIG. 5B illustrates an example embodiment of a thermal cycler 100. In FIG.

5B, the thermal cycler 100 includes a thermal-conductive material 117 that surrounds the heater 115 and that extends beyond the heater 115 to convey heat between the sample container 120 and the TEC 110. In some embodiments, this thermal-conductive material 117 is not located at any critical areas of PCR functionality. This thermal- conductive material 117 may make the cooling phase more efficient and minimize heat loss during the heating phase. In the cooling phase, the TEC 110 removes the heat of the sample container through both the thermal-conductive material 117 and the heater 115. Also, during the heating phase, the TEC 110 heat is conveyed through the thermal-conductive material 117 so that the temperature of the thermal-conductive material 117 increases. And the risk that heat from the heater 115 can leak through the thermal-conductive material 117 is minimized.

[0035] FIGs. 6A-B illustrate an example embodiment of a thermal cycler 100. This embodiment includes a cold sink 130. Also, in this embodiment, the TEC 110 and the heater 115 can move separately, such that the cold sink 130 can move into and out of contact with the heater 115. The cold sink 130 supports the TEC 110 and acts as a thermal sink such that a specific temperature can be easily maintained by the TEC 110. During the heating phase, which is shown in FIG. 6A, the TEC assembly 140 is moved up and does not contact either the heater 115 or the sample container 120, thus enabling the TEC assembly 140 to cool the cold sink 130 while the heater 115 performs a heating phase of the sample container 120. During the cooling phase, which is shown in FIG. 6B, the heater 115 is turned off and the TEC assembly 140 is moved down and into contact with the rest of the assembly, and the isothermal temperature of the cold sink 130 cools the sample container 120 (and the heater 115).

[0036] FIG. 7A-C illustrate an example embodiment of a thermal-cycler shuttle 200. FIG. 7A illustrates an exploded view of the thermal-cycler shuttle 200, FIG. 7B illustrates an unactuated state of the thermal-cycler shuttle 200, and FIG. 7C illustrates an actuated state of the thermal-cycler shuttle 200. In addition to a thermal cycler, the thermal-cycler shuttle 200 includes a cooling fan 210, shoulder pins or screws 220, springs 225, a TEC carriage 230, a temperature detector 240 (e.g., a resistive temperature detector), and a mounting plate 250.

[0037] The TEC 110 is mounted to its associated heat sink 105 and cold sink 130.

The TEC-heat-sink-cold-sink assembly is mounted to the carriage 230 along with the cooling fan 210, and the carriage 230 slides along the shoulder pins 220.

[0038] The springs 225 on the pins 220 apply a force that urges the carriage 230 toward the heater 115, the temperature detector 240, and the sample container 120 with even pressure. Thus, in the default state of the thermal-cycler shuttle 200, the cold sink 130 may contact the heater 115. Although FIGs. 7A-C do not illustrate a moving mechanism (e.g., actuation mechanism), the thermal-cycler shuttle 200 may include a moving mechanism that is used to move the carriage 230 upwards against the downward force of the springs 225 and disconnect the TEC-heat-sink-cold-sink assembly from the heater 115. For example, some embodiments of actuation mechanisms include solenoid or pneumatic actuators that, when energized, apply a force against the force of the springs 225 that slides the carriage 230 upward on the pins 220. The moving mechanism can be triggered via software control in conjunction with regulation of the heater 115 and the TEC 110 to regulate and maintain set point temperatures for each portion of the PCR sequence. The moving mechanism may operate as rapidly as possible to minimize any hysteresis in the heating and cooling cycles. Some embodiments of the moving mechanism actuate in less than 250 milliseconds in both the heating and cooling phases.

[0039] FIG. 8 illustrates a plot of a sample-container temperature versus time for a portion of the full PCR cycling time for one embodiment of a thermal-cycler shuttle. In FIG. 8, the shaded areas denote cooling and heating phases coinciding with the attached and detached states of the TEC-heat-sink-cold-sink assembly. During the annealing hold time (low temperature hold), the TEC-heat-sink-cold-sink assembly was detached, and the heater was powered only enough to maintain this set point temperature until the hold time passes and the heating portion of the cycle restarts.

[0040] One advantage of the above-described exemplary embodiments is their use of the TEC 110 as a heat valve. For example, in some embodiments, when driving power of a first polarity is supplied to the TEC 110, the TEC 110 conveys heat from the heat sink 105 to the heater-side surface of the TEC 110. As a result of this, there is no temperature gradient between the TEC 110 and the heater 115. Because of the even temperature, the heat generated by the heater 115 is not transferred to the TEC 110, and the generated heat goes to the object (e.g., the sample container 120). In the cooling phase, the polarity of the TEC’s driving power is reversed to a second polarity (and the heater 115 is shut off), and the TEC 110 conveys heat from the side of the TEC 110 that is closest to the sample container 120 to the side of the TEC 110 that is closest to the heat sink 105. The heater’s thermal mass is too small to affect the TEC’s removal of the heat from the object (e.g., the sample container 120) much. Also, the TEC 110 cools the object faster than natural cooling. [0041] Also, in embodiments (e.g., the embodiments in FIGs. 6A-B and 7A-C) that separate the heater 115 and the TEC 110, the two members can operate very efficiently. The heater 115 has to heat only the sample container 120, eliminating the additional thermal mass of the TEC 110. While the heater 115 heats the sample container 120, the TEC 110 can run constantly and maintain a very low temperature of the cold sink 130. This enables fast heating and cooling cycles, and it may improve the reliability of the TEC 110 due to the steady-state operating condition.

[0042] As described above, some exemplary embodiments enable a faster-heating heater 115 to more quickly increase the temperature, enable the TEC 110 to function as a thermal insulator in the heating phase, and enable the TEC 110 to decrease the temperature at the cooling phase. To rapidly increase the temperature of an object (e.g., the sample container 120), the generated heat should not leak so that the generated heat is consumed only by the increasing of the temperature of the object. However, if a thermal insulator covers the object’s entire surface, thereby preventing heat leakage, cooling the object can be challenging. With respect to controlling heat flux, the TEC 110 performs well.

[0043] FIG. 9A-B illustrate an example embodiment of a thermal-cycler shuttle 200.

In addition to the carriage 230 and the mounting plate 250, this embodiment shows a moving mechanism 260. In this embodiment, the moving mechanism 260 is an actuator (e.g., a solenoid actuator, a pneumatic actuator). In FIG. 9A, the moving mechanism 260 is activated and, accordingly, exerts a force on the carriage 230 and the mounting plate 250 that urges them away from each other. When the distance between the carriage 230 and the mounting plate 250 increases (e.g., during a heating phase), the cold sink 130 moves out of contact with the heater 115. In FIG. 9B, the moving mechanism 260 has been deactivated (e.g., during a cooling phase), and the carriage 230 has moved toward the mounting plate 250, thereby bringing the cold sink 130 into contact with the heater 115.

[0044] Also, as used herein, the conjunction“or” generally refers to an inclusive“or,” though“or” may refer to an exclusive“or” if expressly indicated or if the context indicates that the“or” must be an exclusive“or.”

Claims

1. A thermal cycler comprising:

a flat sample container;

a thin film heater, wherein the thin film heater is located on a side of the flat sample container;

a thermo-electric cooler located adjacent to the thin film heater;

a heat sink located adjacent to the thermo-electric cooler; and

a thermal insulator, wherein the thermal insulator is located on a side of the flat sample container opposite the thin film heater, the thermo-electric cooler, and the heat sink.

2. The thermal cycler of claim 1 , further comprising circuitry to drive the thermo electric cooler, wherein the circuitry controls alternating a polarity of a supplied power in conjunction with control of heat generation by the thin film heater.

3. The thermal cycler of claim 1 , wherein the thermal insulator consists of low- thermal-conductivity material.

4. The thermal cycler of claim 1 , wherein the thermal insulator is composed of a low-thermal-conductivity material and includes a plurality of small pockets.

5. The thermal cycler of claim 1 , further comprising a thermal-conductive material that surrounds a perimeter of the thin film heater.

6. A thermal cycler comprising:

a planar-shaped sample container;

a thermo-electric cooler located adjacent to the thin film heater;

a moving mechanism that is configured to move the thermo-electric cooler; a heat sink located adjacent to the thermo-electric cooler; and

7. The thermal cycler of claim 6, further comprising circuitry to drive the moving mechanism, wherein the circuitry controls a position of the thermo-electric cooler to contact and to separate from the thin film heater in conjunction with control of heat generation by the thin film heater.

8. The thermal cycler of claim 7, further comprising circuitry that supplies power having a first polarity to the thermo-electric cooler,

wherein, when the thermo-electric cooler receives the power having the first polarity, the thermo-electric cooler transfers heat from a side of the thermo-electric cooler that is closest to the thin film heater to a side of the thermo-electric cooler that is farthest from the thin film heater, and

wherein the circuitry supplies the power having the first polarity to the thermo electric cooler during heat generation by the thin film heater.

9. The thermal cycler of claim 7, further comprising circuitry that supplies power having a first polarity to the thermo-electric cooler,

wherein, when the thermo-electric cooler receives the power having the first polarity, the thermo-electric cooler transfers heat from a side of the thermo-electric cooler that is farthest from the thin film heater to a side of the thermo-electric cooler that is closest to the thin film heater, and

10. A thermal cycler comprising:

a planar-shaped sample container that has a first side and a second side; a thin film heater that has a first side and a second side, wherein the second side of the thin film heater contacts the first side of the planar-shaped sample container; a thermo-electric cooler that has a first side and a second side, wherein, of the first side and the second side of the thermo-electric cooler, the second side is closest to the thin film heater;

a cold sink, wherein the cold sink contacts the second side of the thermo-electric cooler; and

a heat sink located adjacent to the first side of the thermo-electric cooler.

11. The thermal cycler of claim 10, wherein the thermo-electric cooler, the cold sink, and the heat sink are mounted on a carriage, and

wherein the carriage is moveable relative to the thin film heater such that the carriage can move between a first position where the cold sink contacts the first side of the thin film heater and a second position where the cold sink does not contact the first side of the thin film heater.

12. The thermal cycler of claim 11 , further comprising:

a moving mechanism that is configured to move the carriage between the first position and the second position.

13. The thermal cycler of claim 10, further comprising:

a thermal insulator, wherein the thermal insulator is located adjacent to the second side of the planar-shaped sample container.

14. The thermal cycler of claim 10, further comprising a thermal-conductive material that surrounds a perimeter of the thin film heater.