Thermopile differential thermal analysis sensor

A heat flux differential scanning calorimetry method comprising:

• (a) providing a differential temperature sensor in an enclosure, said differential temperature sensor comprising two low electrical impedance thermopiles applied to a single substrate, each thermopile having a set of measuring junctions and a set of thermoelectric reference junctions, the measuring junctions of each thermopile being positioned in its own separate measuring zone, and the thermoelectric reference junctions of the two thermopiles being attached to the substrate in a reference zone common to the two thermopiles;
• (b) placing a reference material on one measuring zone and a sample on the other measuring zone;
• (c) controlling the temperature of the enclosure according to a predetermined heating rate program;
• (d) combining the output of the two thermopiles;
• and
• (e) recording the difference in the temperature of the sample material and the reference material as a function of the temperature of the sample.

A dual-sample heat flux differential scanning calorimetry method comprising:

• (a) providing a differential temperature sensor in an enclosure, said differential temperature sensor comprising two low electrical impedance measuring thermopiles applied to a single substrate, each thermopile having a set of measuring junctions and a set of thermoelectric reference junctions, the measuring junctions of each thermopile being positioned in its own separate measuring zone, and the thermoelectric reference junctions of the two thermopiles being attached to the substrate in a reference zone common to the two thermopiles;
• (b) placing a reference material on each measuring zone;
• (c) controlling the temperature of the enclosure according to a predetermined heating rate program;
• (d) recording the output of the two thermopiles;
• (e) placing a sample material on each measuring zone;
• (f) controlling the temperature of the enclosure according to the predetermined heating rate program;
• (g) recording the output of the two thermopiles;
• (h) separating the signals of the two reference materials;
• (i) separating the signals of the two sample materials;
• and
• (j) combining the results of each sample material measurement with the results of its respective reference material measurement to obtain heat flux data for each sample with respect to its respective reference material,
• wherein step (H) may be performed any time after step (d) and before step (j), and step (i) may be performed any time after step (g) and before step (j).

A power compensated differential scanning calorimetry method comprising:

• (a) providing a differential temperature sensor in an enclosure, said differential temperature sensor comprising two thermopiles applied to a single substrate such that each thermopile has an independent temperature controlled zone, and a heat source/sink zone which is common to both thermopiles, said differential temperature sensor including thermocouples for measuring the temperature of each of the temperature controlled zones, each thermopile having a set of temperature-controlling junctions and a set of heat source/sink junctions, the temperature-controlling junctions of each thermopile being positioned in its own separate temperature-controlling zone, and the heat source/sink junctions of the two thermopiles being attached to the substrate in a heat source/sink zone common to the two thermopiles;
• (b) placing a sample material on one of the temperature controlled zones and a reference material on the other temperature controlled zone;
• (c) controlling the temperature of the enclosure according to a predetermined heating rate program;
• (d) independently supplying direct current electrical currents to each of the thermopiles such that the thermopiles pump heat to and from the heat source/sink regions to the temperature controlled region such that the temperature difference between the sample and reference materials is suppressed;
• and
• (e) measuring and recording the direct current electrical currents supplied to each of the thermopiles.

A dual sample power compensated differential scanning calorimetry method comprising:

• (a) providing a differential temperature sensor in an enclosure, said differential temperature sensor comprising a first and a second thermopile applied to a single substrate such that the first thermopile has a first independent temperature controlled zone and the second thermopile has a second independent temperature controlled zone, and a heat source/sink zone which is common to both thermopiles, said differential temperature sensor including a first thermocouple for measuring the temperature of the first temperature controlled zone and a second thermocouple for measuring the temperature of the second temperature controlled zone, each thermopile having a set of temperature-controlling junctions and a set of heat source/sink junctions, the temperature-controlling junctions of each thermopile being positioned in its own separate temperature-controlling zone, and the heat source/sink junctions of the two thermopiles being attached to the substrate in a heat source/sink zone common to the two thermopiles;
• (b) placing a first reference material on the first temperature controlled zone and a second reference material on the second temperature controlled zone;
• (c) controlling the temperature of the enclosure according to a predetermined heating rate program;
• (d) independently supplying direct current electrical currents to the first thermopile and to the second thermopile such that the first and second thermopiles pump heat to and from the heat source/sink regions to the temperature controlled region such that the temperature difference measured by the first thermocouple and the second thermocouple is suppressed;
• (e) measuring and recording the direct current electrical current supplied to the first thermopile and the direct current electrical current supplied to the second thermopile
• (f) placing a first sample material on the first temperature controlled zone and a second sample material on the second temperature controlled zone;
• (g) controlling the temperature of the enclosure according to the predetermined heating rate program;
• (h) independently supplying direct current electrical currents to the first thermopile and to the second thermopile such that the first and second thermopiles pump heat to and from the heat source/sink regions to the temperature controlled region such that the temperature difference measured by the first thermocouple and the second thermocouple is suppressed;
• (i) measuring and recording the direct current electrical current supplied to the first thermopile and the direct current electrical current supplied to the second thermopile;
• (j) combining the results of the sample material measurement with the results of the first reference material measurement to obtain heat flux data for the first sample with respect to the first reference material;
• and
• (k) combining the results of the second sample material measurement with the results of the second reference material measurement to obtain heat flux data for the second sample with respect to the second reference material,
• wherein steps (b)-(e) may be performed either before or after steps (f)-(i), step (j) may be performed at any point after step (e), and step (k) may be performed at any point after step (i).

The differential scanning calorimeter comprising:

• (a) a temperature-controlled enclosure;
• (b) a differential thermal sensor placed within the enclosure having a first low-impedance thermopile and a second low-impedance thermopile, wherein the first low-impedance thermopile comprises a first set of measuring junctions positioned around a first measuring position and the second low-impedance thermopile comprises a second set of measuring junctions positioned around a second measuring position, wherein each thermopile also comprises a set of thermoelectric reference junctions, and wherein the thermoelectric reference junctions of the first and second thermopiles are positioned in a common reference zone, said thermoelectric reference junctions being attached to the substrate such that the reference junctions of the first and second thermopiles are coincident;
• (c) a first differential temperature amplifier and a second differential temperature amplifier, electrically connected to the differential thermal sensor such that the output of the first thermopile is fed to the first differential temperature amplifier and the output of the second thermopile is fed to the second differential temperature amplifier;
• (d) analog to digital converters connected to each of the differential temperature amplifiers for converting the outputs of the temperature amplifiers into digital data;
• and
• (e) means for combining and storing the digital data, and means for calculating the heat flow to and from the first position relative to the heat flow to and from the second position.

A power compensation differential scanning calorimeter comprising:

• (a) a temperature-controlled enclosure;
• (b) a differential thermal sensor placed within the enclosure having a first low-impedance thermopile and a second low-impedance thermopile, wherein the first low-impedance thermopile pumps heat to and from a temperature-controlling junction at a first position from and to a first heat source/sink junction and the second low-impedance thermopile pumps heat to and from a temperature-controlling junction at a second position from and to a second heat source/sink junction, the temperature-controlling junctions of each thermopile being positioned in its own separate temperature-controlling zone, and the heat source/sink junctions of the two thermopiles being attached to the substrate in a heat source/sink zone common to the two thermopiles, and wherein the heat source/sink junctions of the first and second thermopiles are coincident;
• (c) a first thermocouple measuring the temperature of the first position and a second thermocouple measuring the temperature of the second position;
• (d) means for controlling the current to the first and second thermopiles so as to suppress the difference in the temperatures measured by the first and second thermocouples;
• (e) means for recording the currents supplied to the first and second thermocouples as a function of the temperature measured by the first thermocouple;
• and
• (f) means for calculating the heat flow to and from the first position relative to the heat flow to and from the second position, as a function of the temperature measured by the first thermocouple, from the difference between the current supplied to the first thermopile and the current supplied to the second thermopile.