Thermal cycler for PCR

• US 9,776,187 B2
• Filed: 08/22/2008
• Issued: 10/03/2017
• Est. Priority Date: 03/28/1997
• Status: Expired due to Fees

• Current Assignee: Applied Biosystems LLC (Thermo Fisher Scientific Incorporated)
• Original Assignee: Applied Biosystems LLC (Thermo Fisher Scientific Incorporated)
• Inventors: Atwood, John G., Fawcett, Adrian, Ferrara, Keith S., Hetherington, Paul M., Noreiks, Richard W., Olsen, Douglas E., Widomski, John R., Wittmer, Charles M.
• Primary Examiner(s): HURST, JONATHAN M
• Application Number:
  US12/229,404
• Publication Number:
  US 20080314431A1
• Time in Patent Office: 3,329 Days
• CPC Class Codes: B01L 2300/0829 Multi-well plates; Microtitration plates
• CPC Class Codes: B01L 2300/1822 using Peltier elements
• CPC Class Codes: B01L 2300/1827 using resistive heater
• CPC Class Codes: B01L 3/50853 with covers or lids
• CPC Class Codes: B01L 7/52 with provision for submitting samples to a predetermined sequence of different temperatures, e.g. for treating nucleic acid samples amplification or hybridisation processes per se C12Q1/68; controlling sequential reactions for synthesis B01J19/0046
• CPC Class Codes: C12Q 1/686 Polymerase chain reaction [PCR]
• CPC Class Codes: F25B 21/04 reversible
• CPC Class Codes: F25B 2321/021 Control thereof
• CPC Class Codes: G01R 27/205 Measuring contact resistance of connections, e.g. of earth connections
• CPC Class Codes: G05D 23/1919 characterised by the type of controller
• CPC Class Codes: H10N 10/13 characterised by the heat-exchanging means at the junction
• CPC Class Codes: Y10T 137/1516 Thermo-electric

Abstract

An instrument for performing highly accurate PCR employing an assembly, a heated cover, and an internal computer, is provided. The assembly is made up of a sample block, a number of Peltier thermal electric devices, and a heat sink, clamped together. A control algorithm manipulates the current supplied to thermoelectric coolers such that the dynamic thermal performance of a block can be controlled so that pre-defined thermal profiles of sample temperature can be executed. The sample temperature is calculated instead of measured using a design specific model and equations. The control software includes calibration diagnostics which permit variation in the performance of thermoelectric coolers from instrument to instrument to be compensated for such that all instruments perform identically. The block/heat sink assembly can be changed to another of the same or different design. The assembly carries the necessary information required to characterize its own performance in an on-board memory device, allowing the assembly to be interchangeable among instruments while retaining its precision operating characteristics.

Claims

1. An apparatus for performing the polymerase chain reaction in a plurality of liquid reaction mixtures, said apparatus comprising:

an assembly adapted for cycling a plurality of vials through a series of temperature excursions, the assembly comprising;

a sample block for receiving a microtiter plate having the plurality of vials, wherein in a position of the microtiter plate received by the sample block, the vials are optically accessible by an optical reader without opening the vials;

a heated cover having a platen and a skirt surrounding a perimeter of and extending from the platen, the platen comprising a plurality of recesses sized to allow optical access to the vials, and the skirt being configured to engage and align to the microtiter plate in the position of the microtiter plate received by the sample block;

a plurality of thermoelectric devices,

a heatsink, and

a seal element surrounding and contacting a perimeter of the sample block and configured to seal off the plurality of thermoelectric devices, wherein the seal element is in contact with an inner surface of the heated cover surrounding the sample block; and

a computing apparatus configured for controlling said temperature excursions of said assembly.

2. The apparatus of claim 1 wherein the plurality of thermoelectric devices comprise a plurality of Peltier thermoelectric devices, and the assembly further comprises:

a clamping mechanism that applies pressure to the sample block to clamp the thermoelectric devices between the sample block and the heatsink.

3. The apparatus of claim 2 wherein said sample block comprises:

a plurality of sample wells, for receiving the vials of the microtiter plate, each well having a top and bottom; and

an upper support plate connecting the tops of said sample wells.

4. The apparatus of claim 3 wherein said upper support plate and said sample wells are electroformed as a single piece.

5. The apparatus of claim 1, further comprising a cover for applying a seating force directly to said plurality of vials and for applying a constant temperature to the upper portions of said plurality of vials.

6. The apparatus of claim 1, wherein the assembly further comprises a heater positioned loosely around the perimeter of said sample block.

7. The apparatus of claim 2, wherein said plurality of Peltier thermoelectric devices are matched to provide a temperature within 0.2 C for a given input current.

8. The apparatus of claim 2, wherein each of the plurality of Peltier thermoelectric devices comprise:

a first ceramic layer having bonded copper traces;

a second ceramic layer having bonded copper traces, said second ceramic layer comprising a plurality of ceramic elements; and

a plurality of bismuth telluride pellets positioned between said first ceramic layer and said second ceramic layer and soldered to said bonded copper traces on said first and second ceramic layers.

9. The apparatus of claim 2, wherein said heatsink comprises:

a plate having a top side and a bottom side;

a plurality of fins extending perpendicularly from said bottom side;

a trench extending around the perimeter of said top side to impede heat loss from said perimeter;

a fan placed in close proximity to said fins to control air flow through said fins; and

a recess within said plate for receiving a temperature sensor.

10. The assembly of claim 2, wherein said clamping mechanism comprises:

a spine and said spine having a plurality of openings in said spine for receiving fasteners; and

a plurality of fingers extending laterally from said spine.

11. The apparatus of claim 10, wherein said fingers have a first end protruding laterally from said spine and a protrusion extending downward from said first end.

12. The apparatus of claim 2, wherein said heater comprises an electrically resistive path embedded in a frame-shaped film carrier.

13. The apparatus of claim 12, wherein said electrically resistive path comprises a first set of sections located on opposite sides of said frame-shaped film carrier having a first power density and a second set of sections located on opposite sides of said frame-shaped film carrier having a second power density.

14. The apparatus of claim 2 further comprising an associated memory device capable of storing data related to said assembly.

15. The apparatus of claim 5, wherein

the platen is vertically and horizontally displaceable in relationship to said vials, said platen including:

an array of openings corresponding to locations of said vials, said openings having a perimeter corresponding to a perimeter of said vials;

wherein the skirt extends downward around the perimeter of said platen, said skirt having dimensions corresponding to the perimeter of a standard microtiter tray, said skirt constructed to

engage said perimeter of said tray during vertical displacement of said platen,

cause said openings in said platen to engage said perimeter of said vials, and

apply a seating force on said vials for maintaining a snug fit between walls of said sample vials and said assembly for receiving said sample vials;

a mechanism configured for forcibly lowering said platen to maintain said seating force; and

a heater positioned in close contact with said platen to maintain said platen at a constant temperature.

16. The apparatus of claim 1, wherein the skirt and platen define a volume.