Abstract:
At least one exemplary embodiment of the present invention includes a method comprising providing an input signal from a first differential temperature sensor to a first primary coil of a transformer, and detecting a transient signal from a secondary coil of the transformer, said transient signal arising upon a halting of the input signal. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. This abstract is submitted with the understanding that it will not be used to interpret or limit the scope.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to, and incorporates by reference in its entirety, U.S. Provisional Patent Application Serial No. 60/336,590, filed Dec. 5, 2001, titled “System for Measurement of Temperature Differentials and Minute Current Flow”. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0002]    The wide variety of potential embodiments of the present invention will be more readily understood through the following detailed description, with reference to the accompanying drawings in which: 
       
    
    
       [0003]    [0003]FIG. 1 is a circuit diagram of an exemplary embodiment of a system  1000  of the present invention.  
         [0004]    [0004]FIG. 2 is a block diagram of an exemplary embodiment of an information device  2000  of the present invention.  
         [0005]    [0005]FIG. 3 is a block diagram of an exemplary embodiment of a differential thermocouple  3000  of the present invention.  
         [0006]    [0006]FIG. 4 is a flow diagram of an exemplary embodiment of a method  4000  of the present invention.  
         [0007]    [0007]FIG. 5 is a flow diagram of an exemplary embodiment of a method  5000  of the present invention.  
         [0008]    [0008]FIG. 6 is a circuit diagram of an exemplary embodiment of a system  6000  of the present invention.  
         [0009]    [0009]FIG. 7 is a circuit diagram of an exemplary embodiment of a system  7000  of the present invention.  
         [0010]    [0010]FIG. 8 is a set of inter-linked timing diagrams of an exemplary embodiment of a method  8000  of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0011]    Certain embodiments of the present invention provide a method comprising providing an input signal from a first differential temperature sensor to a first primary coil of a transformer, and detecting a transient signal from a secondary coil of the transformer, said transient signal arising upon a halting of the input signal.  
         [0012]    Certain embodiments of the present invention provide a method comprising detecting a transient signal from a secondary coil of a transformer, the transient signal arising upon an interruption of an input signal from a current-producing transducer provided to a first primary coil of the transformer; and providing a current to the second primary coil of the transformer to cause an energy present in the transient signal to equal a reference energy present in a reference transient signal produced by the secondary coil of the transformer when no temperature differential is sensed by the current-producing transducer.  
         [0013]    Certain embodiments of the present invention provide a system comprising a first differential thermocouple sensor electrically coupled to a first modulator having a duty cycle, an output of said first modulator electrically coupled to a first primary coil of a transformer, and a second differential thermocouple sensor electrically coupled to a second modulator having a duty cycle, said second modulator electrically coupled to a second primary coil of said transformer, said first primary coil balanced with said second primary coil, a secondary coil of said transformer electrically coupled to said first a processor adapted to detect a transient output of said secondary coil of said transformer and filter a steady-state output of said secondary coil of said transformer.  
         [0014]    [0014]FIG. 1 is a circuit diagram of an exemplary embodiment of a system  1000  of the present invention. System  1000  can include a first differential thermocouple  1110  that can be electrically coupled to a first primary coil  1120  of a transformer  1010 . First differential thermocouple  1110  can also be connected via a first controllable switch  1130 , such as a field effect transistor (FET), and a resistor  1140  to ground.  
         [0015]    System  1000  also can include a second differential thermocouple  1210  that can be electrically coupled to a second primary coil  1220  of transformer  1010 . Second differential thermocouple  1210  can also be connected via a second controllable switch  1230 , such as a field effect transistor (FET), and a resistor  1240  to ground. A balancing current device  1270  can provide, via a resistor  1280 , a current signal of a predetermined form, duration, amplitude, and/or direction through second differential thermocouple  1210 .  
         [0016]    The inputs of first and second primary coils can be balanced in terms of resistance, capacitance, and/or temperature coefficients. Any of resistors  1140  and/or  1240  can be of relatively low resistance, e.g. less than one ohm, and can have a very low temperature coefficient. Any resistor used in any embodiment, such as for example resistors  1140  and/or  1240 , can be fabricated from a material having a very low temperature coefficient, such as for example, Mangininand/or Even Ohm.  
         [0017]    In certain embodiments, controllable switches  1130  and/or  1230  can have a nearly infinite resistance in the “off” state and a nearly zero resistance in the “on” state. Certain FET&#39;s, such as the Phillips Semiconductor IRFZ44N and/or the International Rectifier IRL1404, which have an “on” state resistance of 22 milli-Ohms and 4 milli-Ohms, respectively. The state change time and/or slew rate can be on the order of approximately 10 to approximately 100 nanoseconds, including every value therebetween.  
         [0018]    Any resistor of any embodiment (e.g.,  1140 ,  1240 , and/or  1211  (shown in FIGS. 6 and 7), switches  1130 ,  1230 , and/or transformer  1010  can be thermally stabilized prior to and/or during use.  
         [0019]    Transformer  1010  can also include a secondary coil  1320 , which can be coupled via a grounded resistor  1330  to one or more amplifiers  1340 . An amplified output of secondary coil  1320  can be provided to a A/D converter  1350 , and then to a information device  1370 . The analog and/or digital output of secondary coil  1320  can also be provided to an oscilloscope and/or spectrum analyzer  1360 . Electrically coupled to information device  1370  can be an output device  1390 . Information device  1370  can include and/or be coupled to a timing device  1380  that can trigger the opening and closing of switches  1130  and/or  1230 . Information device  1370  can be coupled to current device  1270 .  
         [0020]    When switch  1130  opens its circuit, the magnetic field within transformer  1010  can collapse, permitting current flow and a transfer of energy from primary coil  1120  to secondary coil  1320  of transformer  1010 . Likewise, when switch  1230  opens its circuit, the magnetic field within transformer  1010  can collapse, permitting current flow and a transfer of energy from primary coil  1220  to secondary coil  1320  of transformer  1010 . The energy flow through secondary coil  1320  can comprise a transient output signal in the form of a signal pulse having a time dependent decay. The period of decay can be controlled by adjusting swamping resistor  1330  and/or other well-known circuit parameters.  
         [0021]    As a result of a temperature differential between thermocouple junctions  1114 ,  1212 , and  1214  in a uniform temperature zone  1118 , and temperature at thermocouple junction  1112 , an EMF will be generated and current will flow from the first differential thermocouple  1110  to first primary coil  1120  when switch  1130  is in a conductive state. Via current device  1150 , information device  1370  can input current to the second or balancing primary coil  1220  such that a null output is produced at the secondary coil  1220 . The amount of current necessary to produce the null output can be measured at current device  1150  and/or information device  1370  and employed to compute an output temperature differential signal which can be provided to an output device  1390 , such as a monitor, display, printer, annunciator, speaker, and/or pager.  
         [0022]    In practice, system  1000  can be first set to a null state, i.e. having no EMF or current flow through the secondary coil  1320 . In theory, no current will flow through secondary coil  1320  if all thermocouple junctions,  1112 ,  1114 ,  1212 , and  1214  are at the same temperature, i.e. there is no temperature differential.  
         [0023]    Due to Nyquist noise, Johnson noise, parasitic voltages, capacitance, thermal junction EMF and other factors, a minute current is generated even when all of the thermocouple junctions are at the same temperature.  
         [0024]    In order to set the system to a null state, all of the thermocouple junctions can be set the same temperature and thereafter, a current can be applied to the balancing coil  1220  to adjust the output signal from the secondary coil  1320  to zero. Such nulling current (I x ) can be measured at the balancing current device  1250  and can be established as the null current level for the system.  
         [0025]    The system can utilize the difference between the established null current level (I x ) (with all thermocouple junctions at the same temperature) and the current level (I y ) necessary to balance the system with a temperature differential between the junctions  1112 ,  1114  for the purpose of calculating the value of the temperature differential.  
         [0026]    The difference (I d ) between the null current level and the balancing current level necessary to obtain a zero secondary coil output at the temperature difference, i.e. I x −I y  can be proportional to the degree of temperature difference between the thermocouple junctions  1112 ,  1114 .  
         [0027]    Utilizing device  1000 , a temperature difference can be sensed to within approximately 0.005K, approximately 0.001K, approximately 0.0005K, and/or approximately 0.0001K, including every value therebetween.  
         [0028]    [0028]FIG. 2 is a block diagram of an exemplary embodiment of an information device  2000  of the present invention. Information device  2000  can represent information device  1370  of FIG. 1.  
         [0029]    Information device  2000  can be implemented as a spectrum analyzer, on a general purpose or special purpose computer, such as a personal computer, workstation, minicomputer, mainframe, supercomputer, laptop, and/or Personal Digital Assistant (PDA), etc., a programmed microprocessor or microcontroller and/or peripheral integrated circuit elements, an ASIC or other integrated circuit, a hardware electronic logic circuit such as a discrete element circuit, and/or a programmable logic device such as a PLD, PLA, FPGA, or PAL, or the like, etc. In general any device on which resides a finite state machine capable of implementing the at least a portion of a method described herein may be used.  
         [0030]    Information device  2000  can include well-known components such as one or more communication interfaces  2100 , one or more processors  2200 , one or more memories  2300  containing instructions  2400 , and/or one or more input/output (I/O) devices  2500 , etc.  
         [0031]    In one embodiment, communication interface  2100  can be a bus, a connector, a telephone line interface, a wireless network interface, a cellular network interface, a local area network interface, a broadband cable interface, a telephone, a cellular phone, a cellular modem, a telephone data modem, a fax modem, a wireless transceiver, an Ethernet card, a cable modem, a digital subscriber line interface, a bridge, a hub, a router, or other similar device.  
         [0032]    Each processor  2200  can be a commercially available general-purpose microprocessor. In certain embodiments, the processor can be an Application Specific Integrated Circuit (ASIC) or a Field Programmable Gate Array (FPGA) that has been designed to implement in its hardware and/or firmware at least a part of a method in accordance with an embodiment of the present invention.  
         [0033]    Memory  2300  can be coupled to processor  2200  and can comprise any device capable of storing analog or digital information, such as a hard disk, Random Access Memory (RAM), Read Only Memory (ROM), flash memory, a compact disk, a digital versatile disk (DVD), a magnetic tape, a floppy disk, and any combination thereof. Memory  2300  can also comprise a database, an archive, and/or any stored data and/or instructions. For example, memory  2300  can store instructions  2400  adapted to be executed by processor  2200  according to one or more activities of a method of the present invention.  
         [0034]    Instructions  2400  can be embodied in software, which can take any of numerous forms that are well known in the art. Instructions  2400  can control operation of information device  2000  and/or one or more other devices, systems, or subsystems.  
         [0035]    Input/output (I/O) device  2500  can be an audio and/or visual device, including, for example, a monitor, display, keyboard, keypad, touchpad, pointing device, microphone, speaker, video camera, camera, scanner, and/or printer, including a port to which an I/O device can be attached, connected, and/or coupled.  
         [0036]    [0036]FIG. 3 is a block diagram of an exemplary embodiment of a differential thermocouple  3000  of the present invention, which can represent differential thermocouple  1010  of FIG. 1. Differential thermocouple  3000  can comprise two dissimilar metals joined by brazing, welding, soldering or mechanical fastening, for example. Typical metals employed include copper and constantan.  
         [0037]    A first leg  3015  of copper wire, tube, rod or strip having a known resistance is joined to a wire, tube, rod or strip of constantan  3016  at a junction  3020 . To the other end of the constantan wire, tube, rod or strip  3016  is a second leg  3018 , formed of copper, identical in resistance to the leg  3015 . The second leg  3018  is joined to the constantan wire, tube, rod or strip  3016  at a junction  3022 , with the junctions  3020 ,  3022  being formed by tungsten inert gas welds, of example only. The legs  3015 ,  18  have terminal ends  3024 ,  3026 , respectively. An electromotive force is developed across the terminal ends  3024 ,  3026  of the legs  3015 ,  3018 , in accordance with the equation: EMF=S AB  (T 1 −T 2 ) where S AB  is the Seebeck coefficient for the legs  3015 ,  3018  and the constantan wire, rod or strip  3016  and T 1  and T 2  are the temperatures at the junctions  3020 ,  3022 , respectively.  
         [0038]    [0038]FIG. 4 is a flow diagram of an exemplary embodiment of a method  4000  of the present invention. An analog transient signal, synchronized with the switching of the switches  1130 ,  1230  through the timing device  1380 , can be generated as an output of amplifier  1340 . The analog transient signal can be converted to a digital transient signal at A/D converter  1350 . At activity  4100 , the digital transient signal can be received at information device  1370 .  
         [0039]    At activity  4200 , the digital transient signal then can be analyzed to generate a total energy value E sig  pursuant to the following algorithm:  
                     E   sig     =         lim     n   -&gt;   30              ∑     i   =   1     n                     (       ∫     t   1       t   2                 V                           v         )         n                   wherein                 n     =     the                 number                 of                 times                 integration                 is                   performed   .                     (     Equation                 1     )                               
 
         [0040]    Essentially, a trigger point on the digital transient signal can be obtained and counted for a fixed period of time to sum the total energy in the transient signal and generate a total energy sum. Integration of all amplitudes over the time period can produce a E sig  value representative of the energy present for the predetermine time period in the transient signal. An average of integrated readings, e.g. seven reading, can be employed to improve accuracy.  
         [0041]    At activity  4300 , the value E sig  can employed to determine a balancing current I x  necessary to be applied to the balancing primary coil  1220 , in order to reduce E sig  to a zero value. Expressed mathematically,  
           I   x   =lim   E     sig     →0   f ( E   sig )  (Equation 2)  
         [0042]    At activity  4400 , information device  1370  can output, and/or signal balancing current device  1250  to output, the balancing current I x . At activity  4500 , the balancing current I x  can be measured at information device  1370  and/or balancing current device  1250 .  
         [0043]    [0043]FIG. 5 is a flow diagram of an exemplary embodiment of a method  5000  of the present invention. Method  5000  can include method  4000 .  
         [0044]    At activity  5100 , the temperature T 1  at junction  1112  can be allowed to approach the temperature T 2  at junction  1114 . At activity  5200 , using method  4000 , a corresponding balancing current I 1  can be determined, output, and measured. At activity  5300 , the temperature T 1  at  1112  can be set to a value other than the temperature T 2  of  1114 . At activity  5400 , using method  4000 , a corresponding balancing current I 2  can be determined, output, and measured. At activity  5500 , a current differential I d =|I 1 −I 2 | can be computed.  
         [0045]    At activity  5600 , a corresponding temperature differential and/or EMF, both of which are functions of I d , can be computed. At activity  5700 , the corresponding temperature differential and/or EMF can be output from information device  1370  to output device  1390 .  
         [0046]    To reduce interference, the timing device  1380  can be triggered in phase with line current power supply, e.g. 60 cycle. For example, the timing device can be triggered as the slope of the power supply wave approaches zero. Pattern jitter does not necessarily have a significant effect on the amplitude of the signal when the slope at the trigger point is near zero, i.e. at the peak or valley of the AC sine wave.  
         [0047]    Utilization of an isothermal zone  1020  depicted in dashed lines in FIG. 1 can serve to reduce external thermal influences on the transformer, resistors, and/or switches, and/or can substantially reduce adverse effects of noise. The components within zone  1020  can be placed inside a sealed housing at or below a pressure of one millitorr. The components can be coupled thermally, but not electrically, to a temperature controlled isothermal plate.  
         [0048]    Elimination of junction thermo currents and condensation can be achieved, because the cold side of the isothermal plate can be placed within the housing.  
         [0049]    The plate can be controlled to a fixed value temperature, dependent upon system requirements. Typically the temperature can be maintained at between approximately 273° K to a theoretical value of 0° K, including every value therebetween.  
         [0050]    The housing can be fabricated of a material with high thermal conductivity, e.g. one or more metals such as aluminum or copper. The bottom surface of the housing can dissipate heat from the isothermal plate within the housing. The temperature of exterior surfaces of the housing generally should not be low enough to permit condensation and an increase in local humidity.  
         [0051]    Thermoelectric modules controlled by an independent or integrated controller can be employed to cool the isothermal plate. Heat discharged from the thermoelectric modules can be directed toward the housing to keep the exterior of the housing above the dew point.  
         [0052]    In lieu of thermoelectric modules, cryogenic fluids such as liquid nitrogen can be utilized to cool the isothermal zone within the chamber. Further, thermo piles and/or Peltier coolers can be embedded directly into the isothermal plate.  
         [0053]    Additionally, pure and/or inert dry gases can be employed within the chamber to enhance heat conduction without introducing air. Such control of the environment can reduce system instability attributed to temperature and/or humidity, e.g. can eliminate the effects of changes in magnetic permeability of the air within the transformer.  
         [0054]    [0054]FIG. 6 is a circuit diagram of an exemplary embodiment of a system  6000  of the present invention. System  6000  can resemble system  1000  of FIG. 1. The second differential thermocouple  1210  of FIG. 1 can be eliminated and a balancing grounded resistor  1240  can be added, as shown in FIG. 6.  
         [0055]    As also shown in FIG. 6, a first primary current supply device  1150  and associated resistor  1160  can be connected to the first primary thermocouple circuit.  
         [0056]    First primary current supply device  1150  can provide, via a resistor  1160 , a current signal of a predetermined form, duration, amplitude, and/or direction through first differential thermocouple  1110 . For example, first primary current supply device  1150  can provide a 200 milliamp current in a first direction through differential thermocouple  1110  for a predetermined time, followed by a 200 milliamp current in the opposite direction for the same period of time.  
         [0057]    [0057]FIG. 7 is a circuit diagram of an exemplary embodiment of a system  7000  of the present invention. System  7000  can substantially resemble system  6000  of FIG. 6. The balancing current device  1170  and associated resistor  1180  of FIG. 6 can be moved to the second primary circuit and renumbered as balancing current device  1270  and associated resistor  1280 , as shown in FIG. 7, and can provide a current signal of a predetermined form, duration, amplitude, and/or direction through the second primary coil  1220 .  
         [0058]    An implementation of system  6000  and/or system  7000  can be theoretically viewed as being governed by certain equations, some of which can be found in “Thermodynamics, An Introduction to the Physical Theories of Equilibrium Themostatics and Irreversible Thermodynamics”, by Herbert B. Callen, published by John Wiley &amp; Sons, Inc., New York, May 1961, which is incorporated herein by reference in its entirety.  
         [0059]    Other theoretical views of various embodiments are possible. For example, consider a differential thermocouple (e.g.,  1110 ) composed of two thermoelement materials, A and B, with absolute Seebeck coefficients of SA and SB, and a relative Seebeck coefficient of S. Characterization of the voltage-current characteristic of this thermocouple can show small non-linearities. The voltage across the thermocouple can be given by:  
           E=E   0   +R   e   I+QR   th   S   (Equation 3)  
         [0060]    where E 0  is the Seebeck voltage for the zero current case, Re is the electrical resistance of the thermocouple loop, I is the current, Q is the heat transferred by the Peltier effect away from the A/B junction and into the B/A junction, R th  is the thermal resistance of the junctions with their environment, and S is the Seebeck coefficient.  
         [0061]    The second term on the right side of Equation 1 can be expanded to explicitly show the effects of Joule heating:  
           R   e   I =( R   0   +αΔT ) I ≈( R   0   +αCI   2 ) I   (Equation 4)  
         [0062]    where α is the thermal coefficient of resistance of the wire, and C is a constant.  
         [0063]    The third term on the right side of equation 1) can be simplified using the relation between the Peltier coefficient Π and the Seebeck coefficient, Π=S T:  
         Q=ΠI=STI  (Equation 5)  
         [0064]    The result for the third term, divided by current is:  
           E (Peltier)/ I=R   th   S   2   T   (Equation 6)  
         [0065]    Thus, the ratio E(Peltier)/I can be proportional to absolute temperature, with a mathematical proportionality constant of R th S 2 .  
         [0066]    The R e  term can be separated from the Peltier term in a series of measurements. R 0  can be independent of the measurement speed, whereas the Joule heating and Peltier effects can require a temperature non-uniformity to develop over several milliseconds to seconds. Furthermore, the Joule heating can enter as a higher power of current compared to the Peltier effect. Thus, the three terms can be distinguished by establishing the current-voltage characteristic of the differential thermocouple, for example, at several frequencies.  
         [0067]    The thermal resistance of the junction to its environment can be dependent on the following properties: thermal conductivity of the thermocouple elements; thermal conductivity of any sheath materials surrounding the elements, and/or thermal transport properties of the environment in which the thermocouple is immersed. In general, each of these properties will be temperature dependent.  
         [0068]    The Seebeck coefficient can be temperature dependent as well. For some combinations (type B, for example), the sign of S can even change.  
         [0069]    The prefactor (R th S 2 ) consequently can depend on the choice of thermocouple type, and for any thermocouple type the value of the prefactor can depend on temperature. A measurement of E(Peltier)/I alone does not necessarily give a direct measure of absolute temperature. A measurement of the prefactor, or via a separate combination of measurements, the components of the prefactor, can provide a method for directly measuring absolute thermodynamic temperature.  
         [0070]    [0070]FIG. 8 is a set of inter-linked timing diagrams of an exemplary embodiment of a method  8000  of the present invention that can provide such a direct measure of absolute thermodynamic temperature. Timing diagram  8100  depicts a State 1, where I≠0, and timing diagram  8200  depicts a State 2, where I=0. As a general note, in certain alternative embodiments, openings and/or closings of one or more switches and/or circuits described herein can be reversed.  
         [0071]    For State 1, with the temperature differential of the thermocouple junctions, T 2 −T 1 , approximately equal to 0, using method  4000 , a balancing current I x  can be iteratively determined that drives E sig  to zero or nearly zero, as limited by the sensitivity of the measuring instruments. A State 1 EMF corresponding to I x  can then be computed.  
         [0072]    For State 2, referring to FIG. 6, the circuit between first primary coil  1120  and ground can be opened via switch  1130  so that current does not flow through coil  1120 . First primary current source  1150  can supply a “push” current I 1  through thermocouple  1110  in a first direction for a time t 1 , followed by “pull” current  12  through  1110  in a second, opposite direction for a time t 2 , where I 1 =I 2 , and t 1 =t 2 . Then, the circuit between first primary coil  1120  and ground can be completed via switch  1130  so that current does flow through and charges coil  1120  for a time t 3 =t 2 =t 1 .  
         [0073]    Next, the circuit between first primary coil  1120  and ground can be opened via switch  1130  so that a transient signal is generated from secondary coil  1320 . Using method  4000 , a balancing current I y  can be iteratively determined that drives E sig  to zero or nearly zero, as limited by the sensitivity of the measuring instruments. A State 2 EMF corresponding to I y  can then be computed, and a differential EMF==Δ EMF=|(State 1 EMF−State 2 EMF)| can be computed. Also, a time interval t 4  can be measured from the time the final I x  is determined to the time the final I y  is determined.  
         [0074]    Next, first primary current source  1150  can be set to supply no current, i.e., I 1 =I 2 =0, and the switch can be closed to allow an internal current of the thermocouple can be allowed to flow through first primary coil  1120  to ground. The switch can be opened to generate a transient signal from the secondary coil.  
         [0075]    Then, the process can return to State 1, and a time interval t 5  can be measured from the time the final I y  is determined to the time the final I x  is determined.  
         [0076]    The process can iteratively continue through State 1 and State 2 until Δ EMF converges on a constant and/or the change in Δ EMF converges on 0. The constant value to which Δ EMF converges represents the temperature change in the thermocouple due to Peltier effects. Method  8000  can be repeated as many times as needed to improve the accuracy of the A EMF determination. Time intervals t 1 , t 2 , t 3 , t 4 , and/or t 5 , and/or the work cycle employed in method  8000  can be utilized to compute absolute temperature. A theoretical basis for these computations can be found in, for example, the explanation provided by Callen (referenced supra).  
         [0077]    In addition, method  8000  can include determining a Peltier coefficient and/or Peltier effect of the differential thermocouple independently of EMF. Method  8000  also can include determining an EMF time rate of change due to the Peltier work cycle, thermophysical properties (e.g., materials of construction, specific heat, thermal conductivity, heat capacity, etc.) of the sensor and/or its surrounding environment, and/or a degree of thermal coupling between the sensor and the surrounding environment (e.g., how well the sensor is thermally connected to environment and/or how well heat is exchanged between the sensor and the environment).  
         [0078]    From measurement of the Peltier effect at various temperatures, the thermodynamic temperature scale can be realized. The resolution of the absolute temperature measurements that provide this scale can be from approximately 100 mK to approximately 10 mK to approximately 1 mK to approximately 0.1 mK, and every value therebetween.  
         [0079]    Various embodiments can allow the Peltier work cycle to be related directly to true thermodynamic temperature or absolute temperature. Because a practical temperature scale is not necessarily required, this advancement can allow improvements in many systems of measurement that depend on temperature measurements. Various embodiments present the possibility, minus losses, of measuring heat directly in terms of a work cycle.  
         [0080]    There are numerous potential applications for various embodiments of the present invention. For example:  
         [0081]    Fundamental physical constants can be improved. For example, the accuracy of Boltzman&#39;s constant (k) can possibly be improved by realizing the thermodynamic temperature term of the fundamental gas law.  
         [0082]    A sensor&#39;s thermal coupling to its environment can be assessed.  
         [0083]    The practical temperature scale can be improved. For example, the distance between the thermal energy states of the triple point of water and the triple point of Gallium, respectively, can be determined with greater accuracy and/or precision.  
         [0084]    Thermal properties of materials, such as for example, thermal conductivity, specific heat, etc. can be measured more accurately and/or precisely.  
         [0085]    A better understanding of the conversion of heat to energy, and/or energy to heat, can be obtained by measurement.  
         [0086]    Thermocouples can be used for accurate measurements without the need for recalibration as the long term EMF shifts occurring during use will not necessarily effect the work cycle measurement.  
         [0087]    The system can measure the work cycle of all thermocouple types without specifying the type.  
         [0088]    Although the invention has been described with reference to specific embodiments thereof, it will be understood that numerous variations, modifications and additional embodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the invention. Also, references specifically identified and discussed herein are incorporated by reference as if fully set forth herein. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive.