Rheological and dielectric spectral measurement system

Abstract

A device for performing electrical and rheological measurements of a material sample, the device comprising: a first plate; a second plate; a rotatable drive shaft extending from the motor to rotate the first plate relative to the second plate; and a sample gap between the first plate and the second plate. The second plate includes a first electrode and a second electrode that receive a voltage and form an electric field at the sample gap.

Description

Related applications

[0001] This application claims the benefit of the earlier filing date of U.S. Provisional Patent Application Serial No. 63 / 523,590, entitled “Rheology and Dielectric Spectroscopy Measurement Systems,” filed on June 27, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The disclosed technology generally relates to an apparatus for measuring the properties of materials. More specifically, the technology relates to an apparatus for measuring the rheological properties of a test sample and simultaneously performing impedance spectroscopy on the sample. Background Technology

[0003] Rheometers are well-known for measuring the relationship between stress and strain or strain rate by measuring displacement (more specifically, torque) over a measurement period within a finite sample volume defined by upper and lower geometries (typically plates, etc.). These measurements are typically performed at actively controlled temperatures. Dielectric spectroscopy or impedance spectroscopy (e.g., electrochemical impedance spectroscopy) is used to study the response of a sample subjected to an applied electric field by measuring the dielectric properties of a material sample as a function of frequency. It is often desirable to perform electrical measurements in situ during rheological measurements to correlate the electrical and rheological measurements, for example, to study the relationship between the rheological-dielectric effects and elasticity of viscoelastic materials.

[0004] State-of-the-art rheometers achieve parallel electrical and rheological measurements by applying a voltage to each geometry, allowing electric fields and currents to flow from one geometry (i.e., a rotating plate) through the sample to another geometry (i.e., a stationary plate). During measurements, liquid or dry friction contacts (such as spring brushes, slip rings, liquid electrolytes, etc.) are used to conduct current to or from a moving geometry that rotates continuously during the measurement. However, electrical contact adds undesirable solid or liquid contact with the motor shaft or other geometric components, resulting in unwanted frictional torque for rheological measurements and / or unwanted impedance for impedance measurements, which can limit the instrument's sensitivity. Torque measurements are more accurate if the only torque contribution comes from the sample. Therefore, the resolution of both types of measurements decreases due to a reduced signal-to-noise ratio. Summary of the Invention

[0005] In one aspect, an apparatus for performing electrical and rheological measurements on a material sample includes: a first plate having a conductive surface; a second plate; a rotatable drive shaft extending from a motor to rotate the first plate relative to the second plate; and a sample gap located between the first and second plates. The second plate includes a first electrode and a second electrode that receive a voltage and form an electric field at the sample gap between the conductive surface of the first plate and the first and second electrodes on the second plate.

[0006] Electrical measurements can include impedance spectroscopy measurements.

[0007] The second plate may include a thermally conductive insulator to isolate the first electrode from the second electrode, and may further isolate the first and second electrodes from the environment of the device. The first and second electrodes may be thermally coupled to the environment.

[0008] Thermally conductive insulators may include ceramic coatings.

[0009] The second plate can be formed of a metallic material, and a thermally conductive insulator is coupled to the metallic plate for forming the first and second electrodes from the metallic material.

[0010] The geometry of the first and second electrodes can be determined by thermally conductive insulators.

[0011] The thermally conductive insulator may have a first straight edge communicating with the first electrode and a second straight edge communicating with the second electrode and parallel to the first straight edge. The first straight edge may be separated from the second straight edge by a certain width, which allows the first electrode and the second electrode to be electrically insulated.

[0012] The rotatable drive shaft may include insulating material.

[0013] The first electrode and the second electrode can form a current path and / or electric field from the first electrode and the second electrode through the sample gap to the first plate.

[0014] The first plate may have a stainless steel surface for forming a current path and / or electric field together with the first and second electrodes.

[0015] The device may also include a processor that correlates current flow measurements and torsional force measurements at a first plate in contact with the material sample.

[0016] The device may also include a sensor that detects the current flow through the electric field of the material sample at the sample gap and generates a current flow measurement.

[0017] The device may also include a processor that determines the torsional force measurement based on the current at the motor.

[0018] The device may also include a temperature control device that exchanges heat with the second plate.

[0019] The first and second electrodes can receive voltages of different polarities to form, together with the first plate, a current path and / or electric field through the material sample in the gap.

[0020] On the other hand, an apparatus for performing electrical and rheological measurements on a material sample includes: a first plate; a second plate; a rotatable drive shaft extending from a motor to rotate the first plate relative to the second plate and induce a torsional force on the first plate; and a sample gap located between the first and second plates, the torsional force being applied to the first plate in contact with the material sample at the sample gap. The second plate includes: a first electrode; a second electrode; and a thermally conductive insulator that electrically insulates the first and second electrodes and insulates both electrodes from the environment of the apparatus. The first and second electrodes induce an electric field through the material sample at the sample gap.

[0021] Electrical measurements can include impedance spectroscopy measurements.

[0022] The thermally conductive insulator may include a ceramic coating.

[0023] The second plate can be formed of a metallic material, and a thermally conductive insulator is coupled to the metallic plate for forming the first and second electrodes from the metallic material.

[0024] The rotatable drive shaft may include insulating material.

[0025] The first and second electrodes can form an electric field that includes a current path from the first and second electrodes through the sample gap to the first plate.

[0026] The first plate may have a stainless steel surface for forming an electric field together with the first and second electrodes.

[0027] The device may also include a processor that correlates current flow measurements and torsional force measurements at a first plate in contact with the material sample.

[0028] The device may also include a sensor that detects the current flow through the electric field of the material sample at the sample gap and generates a current flow measurement.

[0029] The device may also include a processor that determines the torsional force measurement based on the current at the motor.

[0030] The device may also include a temperature control device that exchanges heat with the thermally conductive insulator of the second plate.

[0031] The first and second electrodes can receive voltages of different polarities to form an electric field through the material sample in the gap together with the first plate.

[0032] In another aspect, an apparatus for measuring the rheological and electrical properties of a sample includes: a first geometry comprising a conductive surface and a rotatable element for rotating the first geometry; a second geometry comprising a thermally insulating surface, the first geometry being configured to rotate relative to the second geometry; and a gap located between the conductive surface of the first geometry and the thermally insulating surface of the second geometry. The second geometry further includes a first electrode and a second electrode, which, in response to the application of a voltage applied across the first and second electrodes, together with the conductive surface of the first geometry, form an electric field passing through the gap. Attached Figure Description

[0033] The above and other advantages of the present invention can be better understood by referring to the following description in conjunction with the accompanying drawings, in which the same reference numerals indicate the same structural elements and features in the various drawings. For clarity, not every element is labeled in every drawing. The drawings are not necessarily drawn to scale, but rather focus on illustrating the principles of the invention.

[0034] Figure 1 This is a perspective view of a rheometer according to some embodiments of the present invention.

[0035] Figure 2 yes Figure 1 A front cross-sectional view of the rheometer, including illustrations of the current path and electric field lines, as well as the torque applied relative to the material sample being analyzed.

[0036] Figure 3A This is a perspective view of a rheometer according to other embodiments of the present invention.

[0037] Figure 3B yes Figure 3A Front view of the rheometer.

[0038] Figure 4A This is a perspective view of a rheometer according to other embodiments of the present invention.

[0039] Figure 4B yes Figure 4A Front view of the rheometer.

[0040] Figure 5 The circuit of a rheometer according to other embodiments of the present invention is depicted.

[0041] Figure 6 This is a perspective view of a rheometer according to other embodiments of the present invention.

[0042] Figure 7 It is shown in the form of a Nyquist (Cole-Cole) diagram. Figure 6 The graph shows the behavior of the rheometer.

[0043] Figure 8 and Figure 9 It is shown in the form of a Bode plot. Figure 6 The graph shows the behavior of the rheometer.

[0044] Figure 10 Results of experiments performed using a rheometer according to other embodiments of the invention are described. Detailed Implementation

[0045] In this specification, references to "implementation" or "example" indicate that a particular feature, structure, or characteristic described in connection with an implementation or example is included in at least one implementation or example of this teaching. References to specific implementations or examples within this specification do not necessarily refer to the same implementation or example.

[0046] The teachings will now be described in detail with reference to exemplary embodiments or examples as illustrated in the accompanying drawings. While the teachings have been described in conjunction with various embodiments and examples, they are not intended to be limited to such embodiments and examples. In contrast, the teachings encompass various alternatives, modifications, and equivalents, as will be understood by those skilled in the art. Furthermore, features shown or described for one embodiment or example may be combined with features of one or more other embodiments or examples. Those of ordinary skill who have the right to use the teachings herein will recognize additional specific embodiments, modifications, and implementations, as well as other areas of use, within the scope of this disclosure as described herein.

[0047] In short, the embodiments and examples disclosed herein relate to a measuring device, such as a rheometer, for performing rheological-dielectric and / or electro-rheological measurements, such as impedance spectroscopy, for example, electrochemical impedance spectroscopy (EIS). To achieve this, the device has parallel geometries separated by a gap in which a material sample is positioned. One geometry is rotated relative to the other geometry by a DC motor. During the rotation of the geometry, the device measures the torque / stress and / or displacement / strain of the material sample. The stationary geometry has two electrodes electrically insulated from each other by a thermally conductive insulator, such as a ceramic or a polymer such as a plastic, which may include a thin insulating coating with minimal thermal resistance to protect the insulator (e.g., ceramic) from the sample. The thermally conductive insulator provides thermal conduction from a temperature control device to the sample plate and from the sample plate to the temperature control device. The drive shaft extending from the motor to the rotating geometry is also insulated to ensure that the capacitance and conductance between the plate and the environment are minimized, and that the impedance is maximized. Therefore, the two electrodes on the static geometry avoid the need for any electrical contact with the moving parts of the drive motor, which could otherwise affect torque measurement.

[0048] Figure 1 This is a perspective view of a rheometer 10 according to an embodiment of the present invention. Figure 2 yes Figure 1 A front cross-sectional view of the rheometer, including a diagram of the conductive flow path and the torque applied relative to the material sample being analyzed.

[0049] In some embodiments, the rheometer 10 is a parallel geometry rheometer comprising a top plate 12 (also referred to as the first plate) and a bottom plate 14 (also referred to as the second plate), each plate having a specific predetermined geometry for performing measurements. During operation, a material sample (S) is placed between plates 12 and 14, separated by a gap 15 of known width. While the lower plate 14 is stationary relative to the top plate 12, the sample (S) is sheared by applying a force to the top plate 12. This causes deformation of the sample in the gap 15 between plates 12 and 14, which can be characterized in terms of shear stress and shear strain. Based on these quantities and the dimensions of the sample, the shear modulus can be calculated. For example, viscoelastic behavior can be measured, where the shear modulus is independent of shear strain; more specifically, stress-strain relationships can be measured to understand the flow / deformation characteristics of the material sample.

[0050] In some embodiments, the base plate 14 has a first electrode 16 and a second electrode 17 for forming an electric field in the sample. This configuration does not require electrical contact with the rotating top plate 12 via conductive elements, which could otherwise introduce additional undesirable torque into the rheological measurement. This is because the moving plate acts as a passive conductor, rather than a component requiring electrical contact as in the prior art. Figure 2 As indicated by the flow arrow, the top plate 12 operates as a passive conductor to create a path that starts from the first electrode 16, passes through the sample to the top plate 12, and then passes through the sample again from the top plate 12 to the second electrode 17. Thus, there is no electrical contact with the moving plate 12, and no unwanted impedance is added to the drive shaft 11, maintaining torque sensitivity and mechanical measurement.

[0051] In some implementations, an external instrument (such as an LCR meter) may be coupled to the first electrode 16 and the second electrode 17 to apply an oscillating voltage to the rheometer 10. The applied voltage, frequency, etc., can be controlled by the external instrument. The LCR meter may include a sensor to measure current flow from other resulting electrical signals derived from the applied voltage. A processor (not shown) may include program code for synchronizing the electrical measurements with the rheological measurements in time.

[0052] In some embodiments, the base plate 14 has a metal surface 22 that is partially or completely covered with a thermally conductive insulator 21, such as ceramic, plastic, or other materials with good heat dissipation and dielectric strength characteristics. The thermally conductive insulator provides heat conduction from the temperature control device 30 to the sample plate and from the sample plate to the temperature control device. The temperature control device 30 may include a Peltier element, a conductive or conventional element, or other well-known components for applying temperature changes to the base plate 14.

[0053] In some embodiments, the drive shaft 11 includes a coupling 13 formed of an insulating material, such as plastic. The coupling 13 connects the top plate 12 to the shaft 11 and electrically isolates the top plate 12 from the shaft 11 and the environment where current may be present. Electrodes 16, 17 in the base plate 14, having voltages of opposite polarities, are isolated from each other such that one electrode 16 forms a potential across the sample gap 15 reaching the top plate 12 and returning to the other electrode 17. Each electrode 16, 17 can be connected to a source, such as a high-potential and low-potential connector. This allows an external source to apply an oscillating voltage to the electrodes 16, 17 and measure the current, which can be used by a computer to determine the impedance in the sample gap 15. This can be performed over time to determine the conductive and capacitive components of the reactance.

[0054] In some embodiments, the rheometer 10 has at least one sensor 23, such as an optical encoder, on the motor assembly 20, which measures the displacement or torque caused by the rotation of the drive shaft 11 and the force applied to the sample (S) positioned in the gap 15 between the top plate 12 and the bottom plate 14. In other embodiments, a computer processor can calculate the torsional force measurement based on the motor current. During operation, the top plate 12 rotates, and in doing so, the motor can provide torque to the sample (S). The sensor 23 can measure the rotational rate of the top plate 12. In some embodiments, an electric current is applied to the motor assembly 20. The current establishes a magnetic field that generates an electrical torque, thereby causing the drive shaft 11 to rotate. Since the rotational rate of the top plate 12 is measured by the sensor 23, a separate torque sensor is not required. It is well known that the viscosity of the sample and the measured rotational rate can be used to calculate the stress or torque, for example, by the computer processor (not shown) of the rheometer 10.

[0055] As previously described, the rheometer 10 measures the viscosity or elastic properties of a material sample by applying torque from the motor assembly 20 to the drive shaft 11 and the top plate 12. The motor assembly 20 is preferably configured to provide little or no additional torque, such that the rheological measurement relies on most or all of the resistance provided by the material sample to reduce error. For example, the motor may include air bearings, etc., causing the drive shaft to “float” or be surrounded by air, so that no external element other than the air and the sample contacts the drive shaft 11, allowing as much torque as possible on the shaft 11 to come from the sample. When a rotational speed is applied, the material sample (S) experiences viscous resistance. As described above, in a preferred embodiment, the sensor 23 is an optical encoder for measuring the rotational rate of the top plate 12. In some embodiments, the sensor 23 is a force sensor that can continuously measure the deformation rate, shear tension, and strain rate, thereby allowing analysis of time-related behavior. The current applied to the motor forms a magnetic field that generates an electrical torque, causing rotation of the drive shaft 11. In some implementations, sensor 23 is a current sensor that measures the motor current, and the torque signal can be calculated using a computer processor (not shown) based on the motor current. Electrodes are used to create an electric field to measure the current flow, allowing for simultaneous determination of electrical measurements. In doing so, we measure stress / strain mechanical properties along with electrical properties, for example, using a computer processor to correlate the current flow measurement from the sensor with a torsional force measurement determined by the processor based on the motor current.

[0056] Figure 3A This is a perspective view of a rheometer 300 according to another embodiment of the present invention. Figure 3B yes Figure 3A A front view of the rheometer 300. The rheometer 300 has a similar design to... Figure 1and Figure 2 Electrodes 316 and 317 of electrodes 16 and 17 differ in that electrodes 316 and 317 each have a ratio Figure 1 and Figure 2 Electrodes 16 and 17 have a larger surface area, while isolation between electrodes 316 and 317 is maintained, for example, by ceramic material 321 mounted to a metal plate 322 forming a fixed base plate 314. Shaft 311 includes an insulated coupling 313 that provides conductive isolation between the shaft and the conductive top plate 312 to minimize capacitance and conductivity between the plate and the environment, since the aim is to measure such properties only on the sample. The top portion of shaft 311 is configured for coupling to a motor for rotating shaft 311 and top plate 312. Electrodes 316 and 317 are formed with radial symmetry. Conductive lines 318 and 319 may extend from a voltage generator (such as an LCR meter) to electrodes 316 and 317, respectively. Electrodes 316 and 317 are flattened by machining (e.g., grinding) the ceramic material 321 and the surfaces of electrodes 316 and 317 to form a continuous flat surface. In some embodiments, the porous ceramic material 321 may be coated with a thin layer of polymer or adhesive to create a moisture-proof seal without unduly impeding heat transfer. Other thermally conductive insulating materials may also be suitable. In some embodiments, the outer diameters of electrodes 16, 17 are aligned with and have the same diameter as the outer diameter of metal plate 322. The larger surface area of ​​electrodes 16, 17 allows for a greater signal-to-noise ratio by maximizing the capacitance of the sample (not shown) in sample gap 315, as a larger contact area with the dielectric (i.e., gap 15) is achieved. The amount of insulation 321 between electrodes 316, 317 is sufficient to minimize the capacitance between the electrodes. Due to the temperature control provided by temperature control device 330, the insulator 321 is preferably a thermally conductive material.

[0057] Figure 4A This is a perspective view of a rheometer 400 according to another embodiment of the present invention. Figure 4B yes Figure 4A Front view of the rheometer 400. The rheometer 400 is similar to... Figure 3A and Figure 3B The rheometer 300 differs in that the electrodes 416 and 417 have mirror symmetry and the straight edge on the insulating component 421 to maximize the electroactive surface area.

[0058] Figure 5 Circuit 500 of a rheometer for performing rheo-dielectric measurements is depicted according to other embodiments of the invention.

[0059] like Figure 5As shown, two electrodes 516 and 517 are attached to, for example, the aforementioned base plate 514. An impedance analyzer, such as an LCR meter 502, is provided to sense an oscillating voltage to the base plate 514 via the electrodes 516 and 517 and to measure the electrical response.

[0060] Figure 6 This is a perspective view of a rheometer 600 according to another embodiment of the present invention. The rheometer 600 includes electrodes 616 and 617 formed of the same conductive material as the top plate 612. Electrodes 616 and 617 are strip-shaped copper plates with a width of 10 mm, and a 10 mm gap is provided between the electrodes on an insulating plate 614. The top plate 612 is a copper disk with a diameter of 40 mm and is fixed to a rotatable shaft 611 including a black insulating portion. Other details of the rheometer 600 are similar to the rheometer embodiment described above and will not be repeated for the sake of brevity.

[0061] Figure 7 , Figure 8 and Figure 9 These are Nyquist (Cole-Cole) and Bode plots of EIS measurements using a rheometer 600 and a HIOKI LCR meter. These plots are the results of experiments conducted using a 0.1 mM potassium chloride aqueous solution as a sample, with a 1 mm gap between the electrodes and the top plate of the rheometer under test, an AC voltage amplitude of 0.1 V, and an AC frequency range of 4 MHz–8 MHz.

[0062] Figure 10 Data from experiments conducted using the rheometer described herein are provided. This rheometer was configured to include an upper plate with an outer diameter (OD) of 50 mm and a 50 mm square sample plate, with an 8 mm spacing between the electrodes in this setup. The conductive surfaces of the upper plate and lower electrodes are formed of stainless steel for use with Keysight. ™ An LCR meter was used to measure the capacitance across air at different gaps, since the relative permeability of air is known to be close to 1. Using the area of ​​the electrodes enclosed by the periphery of the plates as the capacitor area, and doubling the sample gap as the capacitor dielectric thickness (because the electric field passes through twice), the calculations matched the theoretical predictions for parallel-plate capacitors very well until the gap became relatively small. It can be inferred that this match will remain constant at much lower gaps in the case of more precisely machined parts.

[0063] As mentioned above, conventional rheometers require different types of contact on the moving plate, such as springs, electrolytes, liquid metals, etc., which can affect measurement sensitivity. For example, liquid contact increases measurement error, which cannot be effectively calibrated to reduce below the desired stress level, resulting in measurements that deviate significantly from measurements taken on the same plate without electrical contact. On the other hand, Figures 7 to 9It is shown that since the mechanical properties of the plate are exactly the same as those of a conventional plate, that is, there is no physical contact with the shaft, there is no influence of electrical contact on the measurement. Therefore, the "friction-corrected flow curve" will be exactly the same as the "no EGain" curve, because there is no additional friction to be corrected.

[0064] Figure 10 A summary of the calculations derived from this experiment is included; the formulas are also pasted below if you wish. The same area and distance / length should apply to formulas such as the following (not an exhaustive list):

[0065] Electrical conductance = (conductivity) * area / (conductor length)

[0066] Resistance = (Conductor length) / (Conductivity * Area) = Resistivity * (Conductor length) / (Conductor area)

[0067] Using the same capacitance formula, capacitive reactance = 1 / (2 * PI * frequency * capacitance).

[0068] While various examples have been shown and described, this description is intended to be exemplary and not restrictive, and those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. An apparatus for performing electrical and rheological measurements on a material sample, the apparatus comprising: A first plate, the first plate having a conductive surface; Second board; A rotatable drive shaft extending from a motor to rotate the first plate relative to the second plate; and The sample gap is located between the first plate and the second plate; The second plate includes a first electrode and a second electrode, the first electrode and the second electrode receiving voltage and forming a current path and / or an electric field at the sample gap between the conductive surface of the first plate and the first electrode and the second electrode at the second plate.

2. The apparatus of claim 1, wherein the electrical measurement includes impedance spectroscopy measurement.

3. The apparatus of claim 1, wherein the second plate includes a thermally conductive insulator for isolating the first electrode from the second electrode, and further isolates the first electrode and the second electrode from the environment of the apparatus, and wherein the first electrode and the second electrode are thermally coupled to the environment.

4. The apparatus of claim 3, wherein the thermally conductive insulator comprises a ceramic coating.

5. The apparatus of claim 3, wherein the second plate is formed of a metallic material, and the thermally conductive insulator is coupled to the metallic plate for forming the first electrode and the second electrode from the metallic material.

6. The apparatus of claim 3, wherein the geometry of the first electrode and the second electrode is determined by the thermally conductive insulator.

7. The apparatus of claim 3, wherein the thermally conductive insulator has a first straight edge communicating with the first electrode and a second straight edge communicating with the second electrode and parallel to the first straight edge, the first straight edge and the second straight edge being separated by a certain width, the width being such that the first electrode and the second electrode are electrically insulated.

8. The apparatus of claim 1, wherein the rotatable drive shaft comprises an insulating material.

9. The apparatus of claim 8, wherein the first electrode and the second electrode form the current path and / or electric field from the first electrode and the second electrode through the sample gap to the first plate.

10. The apparatus of claim 1, wherein the first plate has a stainless steel surface for forming the current path and / or electric field together with the first electrode and the second electrode.

11. The apparatus of claim 1, further comprising a processor that correlates current flow measurements and torsional force measurements at the first plate in contact with the material sample.

12. The apparatus of claim 11, further comprising a sensor that detects current flow in the electric field through the material sample at the sample gap and generates the current flow measurement.

13. The apparatus of claim 11, further comprising a processor that determines the torsional force measurement based on the current at the motor.

14. The apparatus according to claim 1, further comprising a temperature control device, the temperature control device exchanging heat conduction with the second plate.

15. The apparatus of claim 1, wherein the first electrode and the second electrode receive voltages of different polarities to form, together with the first plate, the current path and / or electric field through the material sample in the gap.

16. The apparatus of claim 1, wherein the first electrode and the second electrode are formed of the same conductive material as the first plate.

17. An apparatus for performing electrical and rheological measurements on a material sample, the apparatus comprising: First board; Second board; A rotatable drive shaft extends from a motor to rotate the first plate relative to the second plate and to induce a torsional force on the first plate; and A sample gap is located between the first plate and the second plate, and the torsional force is applied to the first plate that is in contact with the material sample at the sample gap. The second plate includes: First electrode; Second electrode; and A thermally conductive insulator is provided that makes the first electrode electrically insulated from the second electrode, and further makes the first electrode and the second electrode electrically insulated from the rotatable drive shaft, wherein the first electrode and the second electrode induce an electric field through the material sample at the sample gap.

18. The apparatus of claim 17, wherein the electrical measurement includes impedance spectroscopy measurement.

19. The apparatus of claim 17, wherein the thermally conductive insulator comprises a ceramic coating.

20. The apparatus of claim 17, wherein the second plate is formed of a metallic material, and the thermally conductive insulator is coupled to the metallic plate for forming the first electrode and the second electrode from the metallic material.

21. The apparatus of claim 17, wherein the rotatable drive shaft comprises an insulating material to prevent the electric field from affecting the torsional force generated by the rotatable drive shaft.

22. The apparatus of claim 17, wherein the first electrode and the second electrode form the electric field, the electric field comprising a current path from the first electrode and the second electrode through the material sample at the sample gap to the first plate.

23. The apparatus of claim 17, wherein the first plate has a stainless steel surface for forming the electric field together with the first electrode and the second electrode.

24. The apparatus of claim 17, further comprising a processor that correlates current flow measurements and torsional force measurements at the first plate in contact with the material sample.

25. The apparatus of claim 24, further comprising a sensor that detects current flow through the electric field of the material sample at the sample gap and generates the current flow measurement.

26. The apparatus of claim 24, further comprising a processor that determines the torsional force measurement based on the current at the motor.

27. The apparatus of claim 17, further comprising a temperature control device that exchanges heat with the thermally conductive insulator of the second plate.

28. The apparatus of claim 17, wherein the first electrode and the second electrode receive voltages of different polarities to form, together with the first plate, the electric field passing through the material sample in the gap.

29. An apparatus for measuring the rheological and electrical properties of a sample, the apparatus comprising: A first geometric structure, the first geometric structure including a conductive surface and a rotatable element for rotating the first geometric structure; A second geometry, the second geometry including a thermally insulating surface, the first geometry being configured to rotate relative to the second geometry; and A gap is located between the conductive surface of the first geometry and the thermally insulating surface of the second geometry, the second geometry further comprising a first electrode and a second electrode, wherein, in response to the application of a voltage applied to the ends of the first electrode and the second electrode, the first electrode and the second electrode together with the conductive surface of the first geometry form an electric field passing through the gap.

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