Patent Publication Number: US-11376599-B2

Title: Thermal cycler apparatus and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of and claims priority to U.S. patent application Ser. No. 13/989,344, filed Jul. 9, 2013, now U.S. Pat. No. 9,446,410, entitled “Thermal Cycler Apparatus with Elastomeric Adhesive”, which claims priority to PCT Application Serial No. PCT/US2011/063005, filed Dec. 2, 2011, entitled “Thermal Cycler Apparatus and Related Methods”, which claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61/419,680, entitled “Thermal Cycler Apparatus and Related Methods”, filed Dec. 3, 2010. All of the aforementioned applications are incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to an apparatus for thermal cycling. Certain embodiments relate more specifically to a method of manufacturing an apparatus and a method of using the apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The written disclosure herein describes illustrative embodiments that are non-limiting and non-exhaustive. Reference is made to certain of such illustrative embodiments that are depicted in the figures, in which: 
         FIG. 1  is a perspective view of a sample plate above a thermal cycler apparatus. 
         FIG. 2  is a perspective view of the sample plate on a thermal cycler apparatus with a partial cut-away view. 
         FIG. 3  is a cross-sectional view of the sample plate on the thermal cycler apparatus taken along cutting line  3 - 3  in  FIG. 2 . 
         FIG. 4  is an isolated sectional view taken along cutting line  4 - 4  in  FIG. 2  of the thermal cycler apparatus. 
         FIG. 5  is an exploded perspective of the sections shown in  FIG. 4  of the sample plate on the thermal cycler apparatus. 
         FIG. 6  is a cross-sectional side view taken along cutting line  6 - 6  in  FIG. 4  of the embodiment of the thermal cycler apparatus and sample plate that are shown in  FIGS. 1-5 . 
         FIG. 7  is a cross-sectional side view of a different embodiment of thermal cycler apparatus. 
         FIG. 8A  is a cross-sectional side view of another embodiment of a thermal cycler apparatus. 
         FIG. 8B  is a perspective view of the embodiment of a thermal cycler apparatus shown in  FIG. 8A  with a cross-sectional view to show a clamp. 
         FIG. 9  is a cross-sectional side view of an additional embodiment of a thermal cycler apparatus. 
         FIG. 10  is a cross-sectional side view of another embodiment of a thermal cycler apparatus. 
         FIG. 11  is a cross-sectional side view of yet another embodiment of a thermal cycler apparatus. 
         FIG. 12  is a cross-sectional side view of the embodiment of the thermal cycler apparatus and sample plate shown in  FIGS. 1-5  that shows the configuration of the thermal block plate. 
         FIG. 13  is a perspective view of the well block shown in  FIG. 1 . 
         FIG. 14  is a cross-sectional side view of the well block taken along cutting line  14 - 14  in  FIG. 13 . 
         FIG. 15A  is a perspective view of the well block and a base plate before they are joined together. 
         FIG. 15B  is a perspective view of the well block and a base plate after they are joined together. 
         FIG. 15C  is a perspective view, looking at the bottom of the wells, of the well block and paired sections of the base plate after removal of portions of the base plate. 
         FIG. 16  is a perspective view, looking into the wells, of the well block and paired sections of the base plate after removal of portions of the base plate. 
         FIG. 17  is a side cross-sectional view, of the well block and paired sections of the base plate after removal of portions of the base plate. 
         FIG. 18  is a plan view of the paired section of the base plate on the well block as shown in  FIGS. 15C-17 . 
         FIG. 19  is a plan view of sections of the base plate that are on a plurality of wells of a well block. 
         FIG. 20  is a perspective view of sections of the base plate that are on a plurality of wells of a well block. 
         FIG. 21  is a perspective view, looking into the wells of the well block and sections of the base plate on a plurality of wells of the well block. 
         FIG. 22  is a side cross-sectional view, of the well block and sections of the base plate on a plurality of wells of a well block. 
         FIG. 23A  is a perspective view of a peltier device receiving a temperature detector. 
         FIG. 23B  is a perspective view of a temperature detector on a peltier device. 
         FIG. 24  is a perspective view of a peltier device on an adhesive on a heat sink. 
         FIG. 25  is an exploded perspective view of peltier devices on a well block, adhesive, and base plates attached to a well block. 
         FIG. 26  is a perspective view of a series of twenty-four peltier devices on a printed circuit and the wires that connect the devices with the printed circuit. 
         FIG. 27  is a perspective view of a well block on the peltier devices shown in  FIG. 26  and their associated wires. 
         FIG. 28  is a block diagram of an automated system for nucleic acid amplification and analysis. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a sample plate  80  with sample wells  82  ready to be positioned on a well block  110  of a thermal cycler apparatus  100  such that each sample well  82  is positioned in a well  120  of well block  110 .  FIG. 2  shows the same components after sample plate  80  is positioned on thermal block plate  110 . The configuration of thermal cycler apparatus  100  can be appreciated by studying  FIGS. 3-6 .  FIG. 3  is an enlarged view of the cut-away provided in  FIG. 2 .  FIGS. 4-6  provided isolated sectional views taken along cutting line  4 - 4  in  FIG. 2  of the sample plate on the thermal block plate.  FIG. 3  and  FIG. 6  show a sample  90 , illustratively for PCR, in each sample well  82  and the components of the embodiment of the thermal cycler apparatus shown at  100  including a well block  110 , a base plate  140 , a layer of adhesive  150 , a peltier device  160 , another layer of adhesive  170  and a heat sink  180 . As shown in  FIGS. 3-6 , well block  110  extends roughly half way up side wall  84  of sample well  82 . However, this is exemplary only and it is understood that other well block heights are within the scope of this invention, such as the tall well block  110 ′ shown in  FIG. 7 . The exploded perspective of the components shown in  FIG. 5  provides the most insightful view as it can be seen that there is a pair of base plates  140  for each 4-well zone, and each pair spans between two adjacent wells. It can also be seen in  FIG. 5  that the layer of adhesive  150  provides an interface with peltier device  160 . Additionally, it can be seen that peltier device  160  is thermally coupled to the pair of base plates  140  via the layer of adhesive  150 . 
     More detail regarding the plurality of wells  120  of well block  110  can be seen in  FIG. 6 . Well  120  is shown having an upper conical sidewall  122 , a transitional sidewall  124 , a lower cylindrical sidewall  126  and a bottom  128  that is flat and extends between lower cylindrical sidewall  126 . Flat bottom  128  rests on base plate  140 , which rests on adhesive  150  to be thermally coupled to peltier plate  160 .  FIG. 6  also shows more details about the configuration of sample well  82  including sidewall  84 , rounded bottom-section  86  of well  82  and the round apex  88 . 
     The layers of adhesive  150  and  170  may be the same material. The adhesive is ductile and flexible, has relatively high thermal conductivity and low viscosity. Illustratively, the adhesive enhances the uniformity of heat transfer between peltier  160  and wells  120 . In one embodiment, the adhesive permits apparatus  100  to be assembled without the use of conventional clamps used to clamp a well block to a heat sink. When an adhesive is used in an embodiments such as apparatus  100 , the adhesive is capable of retaining the peltier device  160  adjacent to the structure contacted by the adhesive such as the wells  120  of well block  110  and/or heat sink  180  even when apparatus  100  is turned upside down without clamping well block  110  to heat sink  180 . 
     Various embodiments of a suitable adhesive are capable of cycling between a temperature at least as high as 95° C. and at least as low as 60° C. at least about 5,000 times, at least about 10,000 times, at least about 100,000 times, or at least about 200,000 times and still be capable of retaining peltier device  160 . Various embodiments of a suitable adhesive may have an elongation, as defined below in the Examples, of at least about 15%, 20%, 22%, 35%, 40%, 50%, 55%, 60%, 70%, 90%, 110%, 120%, 180%, 200%, 400% or ranges within combinations of these values such as about 15% to about 1,000%, about 35% to about 700%, about 70% to about 500%, or between 100% to about 200%. 
     Suitable adhesives may also have an unprimed adhesion lap shear of between about 1 kgf/cm 2  and about 75 kgf/cm 2 , over about 10 kgf/cm 2 , between about 10 kgf/cm 2  and about 45 kgf/cm 2 . The viscosity of the adhesive may range between about 1,000 centipoise and about 200,000 centipoise, between about 10,000 centipoise and about 150,000 centipoise, between about 20,000 centipoise and about 80,000 centipoise, or between about 30,000 centipoise and about 40,000 centipoise. 
     Various embodiments may also have a thermal conductivity, as defined below in the Examples, of at least about 0.39, 0.40, 0.74, 0.77, 0.84, 0.85, 0.9, 0.92, 0.95, 1.1, 1.4, 1.53, 1.8, 1.9, 1.97, 2.2, 2.5 or ranges within combinations of these values such as about 0.74 to about 2.5 or about 0.9 to about 1.8. In one embodiment, the adhesive has a thermal conductivity at 25° C./77° F. of between about 0.7 Watt/meter-K and about 2.5 Watt/meter-K. In another embodiment, the adhesive has a thermal conductivity at 25° C./77° F. of between about 0.8 Watt/meter-K and about 2.0 Watt/meter-K. In one embodiment, the adhesive has a thermal conductivity at 25° C./77° F. of between about 0.9 Watt/meter-K and about 1.5 Watt/meter-K. In yet another embodiment, the adhesive has a thermal conductivity at 25° C./77° F. of over about 1.0 Watt/meter-K. In a further embodiment, the polymer has a thermal conductivity at 25° C./77° F. of about 1.1 Watt/meter-K. 
     Examples of suitable adhesives include thermally conductive silicone pastes, which are non-curing. Specific trade names of suitable thermally conductive silicone pastes, which are non-curing, are provided by those listed in the Examples. 
     The embodiment depicted in  FIG. 7  of a thermal cycler apparatus at  100 ′ differs from apparatus  100  as apparatus  100 ′ does not have base plates such as base plate  140 . Also, apparatus  100 ′ features a well block  110 ′ having wells  120 ′ with taller side walls  122 ′. The embodiments of the well blocks disclosed herein may each have such taller side walls instead of side walls  122  or side walls  422 . Wells  120 ′ have flat bottoms  128  that are directly over and in contact with a layer of adhesive  150 . While the configuration of apparatus  100 ′ provides less area for layer of adhesive  150  to bond to relative to the configuration of apparatus  100 , the configuration of apparatus  100 ′ also permits faster heat transfer between peltier device  160  and wells  120 ′ as there is less mass for the heat to pass through without a base plate. 
       FIGS. 8A-8B  depicts another embodiment of a thermal cycler apparatus at  200 . Apparatus  200  features a carbon sheet or grease or other non-binding thermal interface material at  270  instead of an adhesive. Optionally, the non-binding thermal interface material  270  may also replace the layer of adhesive  150 . Because carbon sheet or grease does not retain peltier device  160  adjacent to heat sink  180  when apparatus  100 ′ is turned upside down, it is necessary to clamp well block  110  to heat sink  180  with a clamp bar  230 . Clamp bar  230  may alternatively rest on a thin compression pad or compliant layer  232  that may be formed from a suitable material such as silicone. Clamp bar  230  extends across adjacent base plates  140  and can be attached at its ends with conventional mechanisms for clamp systems to the apparatus  200 . It is also possible use clamp screws that extend through the well block and into the heat sink. Various clamp bar and clamp screw embodiments are known in the art. 
       FIG. 9  depicts another embodiment of a thermal cycler apparatus at  300 . Apparatus  300  features solder  370  between peltier device  160  and heat sink  180 . As with the embodiments shown in  FIGS. 6-7 , with this configuration, it is also not necessary for well block  110  to be clamped to heat sink  180 . 
       FIG. 10  depicts another embodiment of a thermal cycler apparatus at  400 . Apparatus  400  features a well block  410  with wells  420  that have sidewalls  422 , which transition to rounded bottoms  426  and have a rounded apex  428  instead of a flat bottom. Also, the rounded bottom of each well  420  rests in solder  440  illustratively with rounded apex  428  directly contacting peltier device  160 . Wells with flat bottoms such as wells  120  can also be soldered like wells  420  directly to a peltier device, as shown in  FIG. 7 . 
       FIG. 11  depicts another embodiment of a thermal cycler apparatus at  500 . Apparatus  500  features well block  110 , on base plate  240 , which is soldered to peltier device  160  via solder  350 . Peltier device  160  rests on non-binding thermal interface material  270  so clamp bar  230  is also used with the same configuration as described above with respect to apparatus  200 . In addition to the apparatuses discussed above and depicted at  100 ,  100 ′, 200 ,  300 ,  400  and  500 , other combinations may also be used. For example, apparatus  500  can be modified by replacing solder  350  with adhesive  150  or with non-binding thermal interface material  270  such as carbon or grease. 
       FIG. 12  corresponds with the embodiment shown in  FIGS. 1-6  and shows all of the components of a single zone. Apparatus  100  has a well block  110  that comprises a plurality of 4-well zones, wherein each 4-well zone comprises a first pair of wells  120  and a second pair of wells  120 , and wherein each first pair of wells  120  and each second pair of wells  120  are respectively over a first base plate and a second base plate such that one peltier device  160  provides for heat transfer for one 4-well zone. Each peltier device  160  heats or cools a pair of base plates  140  via adhesive  150  to heat or cool the sample in the four sample wells via each bottom  128  and side walls  122  of the four wells  120 . Heat sink  180  is thermally connected to peltier device  160  via adhesive  170 . It is understood that the 4-well zone is illustrative only, and that each zone may comprise various other numbers of wells. 
     More detailed information about the configuration of well  120  can be appreciated with reference to  FIGS. 12-14 .  FIG. 14  provides references for describing the dimensions of well  120 . The length of lower cylindrical sidewall  126  is identified as L 1 , the diameter of flat bottom  128  is identified as L 2 , and the depth of well  120  is identified as L 3 , and the angle between the upper conical sidewall  122  and a line extending from the lower cylindrical sidewall  126  is identified as α 1 . The angle, α 1 , between the upper conical sidewall  122  and the lower cylindrical sidewall  126  in one embodiment is about 16°, such as 16.3°, however other angles are within the scope of this invention and may approximately correspond to external dimensions of commercially available microtiter plates. The angle, α 2 , between the lower cylindrical sidewall  126  and flat bottom  128  is equal to or slightly greater than 90°, such as 92°, however other angles are within the scope of this invention. While a 90° angle α 2  is contemplated, angles slightly greater than 90° may be desired, illustratively to ease removal of well block  110  from the mold used in the manufacturing process. It is understood that if angles slightly greater than 90° for α 2  are used, that cylindrical sidewall  126  will define a generally cylindrical section that is, in fact, slightly conical. Illustratively, α 2  is less than 90°+α 1 , illustratively 95° degrees or less, and more illustratively, 92° or less. 
     An advantage of flat bottom  128  relative to prior art configurations is that the shape can be manufactured with greater uniformity, and provides additional surface area that enables heat to be transferred with greater uniformity and at a more rapid rate. However, it is understood that flat bottom  128  may have rounded edges near sidewall  126  or otherwise may not be completely flat from one side of cylindrical sidewall  126  to the other. Moreover, because lower cylindrical sidewall  126  does not interfere with insertion of the sample well  82  into well  120 , the shape of the well  120  allows sample well  82  to have maximal contact with the sidewall  122  of the wells in each well block. 
     An average well  120 ′ of well block  110 ′, as shown in  FIG. 7 , is close to the height of sample well  82  and illustratively has a depth of about 0.5 inches-0.6 inches for a 96-well plate. Such a well block allows sample well  82  to be filled with a large sample volume and also mitigates against the effects of a heated lid that may be at a static temperature. Most embodiments illustrated in this disclosure, including in  FIGS. 1-6, 8-17, 20-22, and 25 , have a depth of well  120 , L 3 , that is shorter, illustratively only about 0.3 inches for a 96-well plate. An advantage of this configuration is a decrease in the incidence of sidewall condensation, particularly during cooling. Due to reduced well height relative to a convention well, another advantage of this configuration is a decrease in well block mass relative to prior art configuration, which increases the thermal cycling rate. It is understood that the choice of height of the wells of the well block depends on the specific application and that either configuration may be used with the various embodiments disclosed herein. 
       FIGS. 15A-15C  depict an illustrative method of manufacturing a well block assembly  149  to yield pairs of base plates on the bottoms of wells. First a precursor base plate sheet  142  is obtained as shown in  FIG. 15A  and then is attached to flat bottom  128  illustratively by soldering, as illustrated in  FIG. 15B . Then, portions of the precursor base plate sheet are removed to yield pairs of base plates  144   a ,  144   b  that span adjacent wells, as shown in  FIG. 15C . The portions of the base plate sheet may be removed by any conventional method such as machining, punching, stamping, or dicing. Alternatively, the base sheet could be cut first and the base plates added thereto. By removing portions of precursor sheet  142 , channels  141  are formed that may be used as space for wiring, illustratively to wire the peltiers  160  or temperature detectors  167 , as shown in  FIGS. 26-27 .  FIG. 16  shows another view of well block  110  with paired sections of the base plate.  FIG. 17  provides the identification of the length of base plate  140 , which is L 4 . 
       FIGS. 18 and 19  provide the same view of different embodiments.  FIG. 18  corresponds with apparatus  100 .  FIG. 19  shows base plates  240  that connects more than four wells. Such an embodiment may result in increased uniformity, albeit with a reduction in control. Base plates  240  are also more easily used with a clamp bar such as clamp bar  230  shown in  FIGS. 8A-8B  and  FIG. 11 . A solid base plate may be acceptable in some embodiments, illustratively with recessed temperature sensors. 
       FIGS. 20-22  show the same embodiment depicted in  FIG. 19  but from a different views.  FIG. 22  provides the identification of the length of base plate  140 ′, which is L 5  when it spans wells that are at the perimeter and is L 6  when it spans wells not at the perimeter. 
       FIGS. 23A-23B  provide more detailed views of peltier device  160 . Between plates  162  and  164 , heat directing element  163  is connected to printed circuit  166 , which is connected, illustratively by solder or adhesive, to a temperature detector  167 , illustratively a resistance temperature detector. 
       FIGS. 24-25  depict a method of manufacturing apparatus  100 .  FIG. 24  shows peltier device  160  being placed on adhesive  170 .  FIG. 25  shows the subsequent steps of placing adhesive  150  on peltiers  160  followed by placement of base plates  140  on adhesive  150 . An advantage of this configuration is that clamps or screws such as those described above are not necessary. However, use of such clamps or screws is not precluded with apparatus  100 . 
     As shown in  FIGS. 24-25  twenty-four peltiers  160  are used, although it is understood that more or fewer peltiers  160  may be used, depending on the desired application. Illustratively, for a 96-well plate, between 4 and 96 peltiers may be used, with zones of 24 wells if 4 peltiers are used, down to zones of one well, with each peltier controlling an individual well. In one illustrative embodiment, each peltier device  160  is individually driven. Illustratively, the peltiers  160  are not in series nor parallel. Such may be used to provide greater well-to-well uniformity, for example by heating the exterior peltiers to a slightly higher temperature, thus reducing the issue of cooler maximum temperatures in the exterior wells, particularly in the corner wells. Individually driven peltiers  160  also may be used to provide for a temperature gradient across the plate. 
       FIG. 26  is a perspective view of a series of twenty-four peltier devices  160  on heat sink  180  and their wires that connect peltier devices  160  to a printed circuit. The printed circuit is connected to the temperature detectors  167 . 
       FIG. 27  shows well block  110  on peltier devices shown in  FIG. 26  and their associated wires  181 . As seen in  FIG. 15C , there is a channel  141 , which is a space, between each pair of base plates  140 , so when well block  110  and base plates  140  are placed on peltier devices  160 , the wires extending from peltier devices  160  may extend through this space. 
       FIG. 28  shows an automated system containing thermal cycler apparatus  100 . Thermal cycler apparatus  100 , is mounted within a housing  101 . Well block  110  is positioned to receive sample plate  80  once sample plate  80  is inserted into opening  102 . Opening  102 , as shown in  FIG. 28  is a movable lid, but it is understood that opening  102  can be any type of opening as are known in the art, including a slot, a door, etc. Optionally, the lid mechanism may close down onto sample plate  80  to seal the sample within sample wells  82  or to force wells  82  of sample plate  80  into better contact with wells  120  of well block  110 . If real-time data acquisition or post-PCR melting is desired, an optics block  109  may be provided for sample excitation and detection. Optics block  109  may provide single-color or multi-color detection, as is known in the art. 
     The system includes a computing device  104 , which may comprise one or more processors, memories, computer-readable media, one or more HMI devices  103  (e.g., input-output devices, displays, printers, and the like), one or more communications interfaces (e.g., network interfaces, Universal Serial Bus (USB) interfaces, etc.), and the like. Computing device  104  may be provided within housing  101 , or may be provided separately, such as a laptop or desktop computer, or portions of computing device  104  may be resident within housing  101 , while other portions are located separately and may be coupled through wiring or wirelessly. Computing device  104  may be configured to load computer-readable program code for controlling thermal cycler apparatus  100  and optics block  109 . In one illustrative embodiment, thermal cycler apparatus  100  in housing  101  may be provided in an automated system with a robotics unit  105 . The robotics unit  105  may be programmed to load the samples into sample wells  82  and then load sample plate  80  into housing  101  through opening  102 . Optionally, robotics unit  105  may also prepare the samples prior to loading into sample wells  82 . Teach points may be used by robotics unit  105  for orienting plate  80  into well block  110 . Teach points  134   a - c  are best seen in  FIG. 16 , where three teach points are used. In this illustrative arrangement, teach point  134   a  is located near a first edge  177 , while teach points  134   b  and  134   c  are located near a second edge  178  of well block  110 . With three teach points, the robotics unit  105  can easily identify the orientation of well block  110 . However, it is understood that three teach points is illustrative and any number of teach points can be used. Control of robotics unit  105  may be through computing device  104 , or robotics unit  105  may be controlled by a separate processor. Optionally, robotics unit  105  may be configured to load samples into multiple thermal cycler devices. 
     Examples of an Adhesive 
     An exemplary method for determining the tensile strength and elongation of elastomeric materials is described below. This method is not ASTM D412 but is based closely thereon. For this exemplary method, the apparatus may be the following, although similar equipment may be used provided it is capable of the accuracy and precision required. The dies used may be the ASTM D412 die C or others as specified, from any suitable source. The marker used may be a bench marker with two parallel lines 1+/−0.003 in. (2.54+/−0.0076 cm) apart for dies C and D and 2+/−0.003 in. (5.08+/−0.0076 cm) for A, B, E and F, from any suitable source of commercial rubber stamp pads. The micrometer used should be capable to +/−0.001 in. (0.02 mm) and exert a total force of no more than 1.5 psi (10 kpa), from any suitable source. The molds used may be aluminum and may prepare samples at least 4 in.×4 in. (10.2 cm×10.2 cm) and between 0.06 in and 0.12 in. (0.15 cm and 0.30 cm) thick, as specified, from any suitable source. The press may be any small hand operated press suitable for cutting the test bars. Examples of such presses include tensile testers from Monsanto Instruments, Akron, Ohio; Instron Corp., Canton, Mass.; or United Testing Systems, Auburn Heights, Mich. 
     It is noted, and a skilled artisan would be aware, that the results may be adversely affected by improper care of the dies. The edges should be sharp and protected at all times from nicks. 
     A standard test slab (0.080+/−0.008 inches thick, 2.0+/−0.2 mm) of the material to be tested was molded and cured as specified. The slab was allowed to rest at room temperature on a flat surface for at least 3 h. The room in which the testing was performed was maintained at 23+/−2° C. Using the ASTM D412 Disc or other specified die and a press, three bars (or the specified number of test bars) were cut parallel with the grain, if any, of the material. 
     It is noted that straight samples may be pulled if enough material is not available to cut the normal test bars; however, the width must be measured. In these instances, A=W/[(D) (L)] where A is the area in cm 2 ; W is the weight in air in g; D is the density in g/cm 3 ; and L is the length in cm. Similarly, pieces of tubing too small to cut suitable bars from may be pulled, if the area is calculated. For tubing with OD ⅜ in. (0.95 cm) or less, this may be approximated. In other instances, A=(CSA,1)−(CSA,2); where CSA,1 is the area using outside diameter and CSA,2 is the area using inside diameter. 
     The thickness {to 0.001 in. (0.02 mm)} of each test bar was measured in three places from end to end of the reduced section. The median of the three measurements was recorded as “Th”. If the measurements varied by more than 0.003 in. (0.07 mm), the bar was discarded. For instances where tension set is required, each of the test bars was marked with a 1 in. (2.54 cm), “L,o” bench mark that was equidistant from the center line of the reduced section and perpendicular to its longitudinal axis. It is noted that whenever samples were heat aged or stored prior to testing, they are marked for identification by notching the ends rather than with an ink mark if there is the possibility of the ink affecting the samples. 
     The test bar was placed in the grips of the tester and adjusted so the tension was uniformly distributed over the cross section of the bar during the test. The machine was started, the bar was stretched to the breaking point and the necessary data to complete the calculations as specified was recorded. It is noted that the instrument may be equipped with a mechanical or electrical measuring system and may have a manual or automatic recording system. The calculations may be performed by a computer attached to the test instrument. 
     In this exemplary method, the rupture points of the bars should be observed as an indication of problem with the dies. Thus, if all samples break in the same area, a die problem may exist. If this occurred, the test was repeated with the remaining test bars. The required result was calculated and the median values were reported unless another reporting mode is specified. If specified, other reporting modes or values may be reported, e.g. average, weighted average, lowest value, highest value. 
     The median value of three bars was used unless either one or more of the values did not meet the specified requirements when testing for compliance with a specification, or the sample was a referee or round robin material. In these instances, a total of five bars were pulled and the median value reported. 
     If there was any indication that the results were invalid, the total test was repeated. Examples of such indications are minimum and maximum values+/−15% from the median; constant rupture point on all bars (i.e. a damaged die); nicks in the edges of the bars due to poor cutting techniques or damaged dies; and air bubbles, flow marks, etc., which might indicate poor sample preparation. 
     If tension set is required, the two pieces were allowed to rest 10 min, then carefully fit together to give full contact at the point of the break. The distance between the bench marks was measured and recorded as “L,2”. 
     In this exemplary method, the tensile tester, bench marker, and micrometer were on a routine calibration schedule. 
     The following definitions are applied to terms used in this method. 
     Elongation is the extension of a test bar to rupture expressed as a percentage of the original length and measured by the bench marks. It is also known as ultimate elongation or elongation at break. The term may also be used to describe a specific percentage extension when used with modulus or tension set (i.e. modulus at 200% elongation). Elongation, % is calculated as [{(L,1)−(L,o)} (100)]/(L,o) where L,1 is the length at break between bench marks and l,o is the original length between bench marks. With an elongation gage and a 1 in. (2.54 cm) bench mark spacing, the percentage elongation may be read directly as E, %. 
     Modulus is the applied force per unit of original cross sectional area of a test bar at a specific percentage elongation (i.e. tensile stress at a given elongation). This term is normally accompanied with a specified percentage elongation and is generally written “Modulus, 200.” Modulus is calculated as [(F) (Factor)]/[(W) (Th)]=psi #, where F is the force applied or the dial reading at E; Factor is instrumental factors required to convert the dial reading into pounds of force; W is width of the reduced section before pulling {0.250 in. (0.635 cm) for die C}; “Th” median thickness of the reduced section before pulling, E is specified percentage elongation, and #KPa is psi×6.8948. 
     Tensile strength is the maximum tensile stress applied during the rupture of a test bar. Tensile strength is calculated as [(F) (Factor)]/[(W) (Th)]=psi #, where all symbols are as defined as above except F; F is the maximum force applied to break the sample. 
     Tensile stress is the applied force per unit of original cross sectional area of a test bar. 
     Tension set after break is the set (extension) remaining after a test bar has been stretched to rupture and allowed to retract for 10 min, expressed as a percentage of the original length of the bench mark. This is not to be confused with tension set. Tension set after break is calculated as Set, %=[{(L,2)−(L,o)} (100)]/(L,o), where L,o is the original length between bench mark and L,2 is the length between bench marks after 10 min rest after break. 
     Tension set is the set (extension) remaining after a test bar has been stretched to a given percentage elongation and allowed to retract, expressed as a percentage of the original length of the bench mark. The value is obtained as follows: the bar is placed in the grips. The grips are spread at 20 in./min (50.8+/−2.5 cm/min) to the specified percentage elongation. The machine is secured and the sample is allowed to remain under tension for a specified time. The sample is released quickly but without snap and the bar is removed. The bar is allowed to rest flat for a specified time and the distance between the bench marks to 1% of the original length is measured. Calculate as for tension set after break. The result is generally reported with the percentage elongation, such as “tension set, 200.” 
     The precision of the various results should be within +/−15% to ensure repeatability, reproducibility, and accuracy. 
     Example 1 
     The thermally conductive compounds listed in Table 1, below, are available from DOW CORNING, and were all tested using the exemplary method described previously. Relevant data is shown. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Thermal conductivity at 25° C./77° F., Watt/meter-K; Elongation, %; 
               
               
                 Viscosity, centipoise; and Unprimed Adhesion Lap Shear, kgf/cm 2 . 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 unprimed  
               
               
                   
                 thermal 
                   
                   
                 adhesion 
               
               
                 product 
                 conductivity 
                 elongation 
                 viscosity 
                 lap shear 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 SE4420 
                 0.9 
                 90 
                 108,000 
                 35 
               
               
                 SE4422 
                 0.9 
                 120 
                 200,000 
                 16 
               
               
                 SE4486 
                 1.53 
                 50 
                 19,000 
                 14 
               
               
                 SE9184 
                 0.84 
                 70 
                 nonflow 
                 21 
               
               
                 SE4400 
                 0.92 
                 90 
                 76,000 
                 30.9 
               
               
                 SE4402 
                 0.92 
                 120 
                 34,000 
                 34 
               
               
                 SE4450 
                 1.97 
                 40 
                 61,000 
                 37 
               
               
                 1-4173 
                 1.9 
                 20 
                 58,000 
                 45 
               
               
                 1-4174 
                 1.9 
                 22 
                 58,000 
                 41 
               
               
                 Q1-9226 
                 0.74 
                 110 
                 50,000 
                 NA 
               
               
                 3-1818 
                 1.8 
                 20 
                 68,700 
                 35.9 
               
               
                 Q3-3600 
                 0.77 
                 55 
                 4,700 
                 NA 
               
               
                 3-6605 
                 0.85 
                 90 
                 47,000 
                 24.6 
               
               
                 3-6751 
                 1.1 
                 35 
                 10,000 
                 39 
               
               
                 3-6752 
                 1.8 
                 15 
                 81,000 
                 37.9 
               
               
                 3-6753 
                 1.4 
                 35 
                 11,000 
                 37.9 
               
               
                 SE4410 
                 0.92 
                 60 
                 3,500 
                 26 
               
               
                 SE4447 
                 2.5 
                 20 
                 140,000 
                 NA 
               
               
                 SE4448 
                 2.2 
                 NA 
                 102,000 
                 NA 
               
               
                 3-6651 
                 1.1 
                 180 
                 32,000 
                 NA 
               
               
                 3-6652 
                 1.9 
                 70 
                 34,000 
                 NA 
               
               
                 3-6655 
                 1.8 
                 90 
                 33,000 
                 NA 
               
               
                   
               
            
           
         
       
     
     Example 2 
     The compound AS1808, available from ACC SILICONES (Somerset, UK), was tested using a method comparable to the exemplary method described previously. Its thermal conductivity at 25° C./77° F. (Watt/meter-K), Elongation (%), and Overlap Shear Strength Aluminum (kg/cm 2 ) are 1.79, 91, and 12.31, respectively. 
     It will be understood that reference to PCR is illustrative only and the devices of this disclosure may be compatible with other methods of amplification. Such suitable procedures include strand displacement amplification (SDA); nucleic acid sequence-based amplification (NASBA); cascade rolling circle amplification (CRCA), Q beta replicase mediated amplification; isothermal and chimeric primer-initiated amplification of nucleic acids (ICAN); transcription-mediated amplification (TMA), and the like. Asymmetric PCR may also be used. Therefore, when the term PCR is used herein, it should be understood to include variations on PCR as well as other alternative amplification methods, as well as post-PCR processing, such as melt curve analysis. Illustrative examples of suitable melt curve analysis can be found in U.S. Pat. No. 7,387,887, which is incorporated herein by reference. Furthermore, the devices of this disclosure may be suitable for a variety of other biological and non-biological reactions that require temperature control. 
     It will be understood by those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles presented herein. For example, any suitable combination of various embodiments, or the features thereof, is contemplated. 
     Any methods disclosed herein comprise one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified. 
     Throughout this specification, any reference to “one embodiment,” “an embodiment,” or “the embodiment” means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment. 
     Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than those expressly recited in that claim. Rather, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles set forth herein. 
     The claims following this Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims. Recitation in the claims of the term “first” with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. Embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.