Rheometer for simultaneous rheological and electrical measurements

Abstract

An apparatus for measuring rheological and electrical properties of a sample is described. The device comprises a first geometry comprising a first fixation element and a second fixation element, each of which is electrically conductive and has a surface disposed to face a surface of the other fixation element across the gap. The first fixing element and the second fixing element are electrically isolated from each other. The apparatus also includes a second geometry including a rotatable element disposed in the gap and configured to rotate between the first stationary element and the second stationary element. The rotatable element is electrically conductive such that, in response to the application of a voltage difference across the first and second fixed elements, a first electric field is generated between the first fixed element and the rotatable element, and a second electric field is generated between the rotatable element and the second fixed element.

Description

Related applications

[0001] This application is a non-provisional patent application claiming priority to U.S. Provisional Patent Application No. 63 / 523,858, filed June 27, 2023, entitled “Rheometer for Simultaneous Rheological and Electrical Measurements,” which is incorporated herein by reference. Technical Field

[0002] The disclosed technology generally relates to the rheological and electrical characterization of materials. More specifically, this technology relates to an apparatus for simultaneously performing electrical and rheological measurements on a test sample. Background Technology

[0003] Simultaneous measurement of the electrical and rheological properties of a material sample allows for the correlation of changes in these properties. To achieve this, an electric field is established within the sample, and the electrical properties are measured over a stress / strain gradient during the rheological measurement.

[0004] Current state-of-the-art systems achieve simultaneous electrical and rheological measurements by using the moving and fixed geometries of the rheometer as electrodes of opposite polarity, allowing current to flow from one electrode through the sample to the other. Liquid or sliding friction contacts are employed to conduct current between the continuously moving and fixed geometries. Potassium chloride solution and liquid metal alloys are examples of conductive liquids, sometimes used for electrical contact with the moving geometry. Spring brushes can be used as sliding friction contacts. Liquid or sliding friction contacts introduce unfavorable frictional torque for rheological measurements and unfavorable impedance for impedance measurements. Therefore, the resolution of both types of measurements decreases due to a reduced signal-to-noise ratio. Unfavorable friction is particularly problematic in combined motor transducer rheometers. More specifically, the torque required to rotate the moving geometry is simultaneously used to determine sample material properties, thus limiting the instrument's measurement sensitivity to an additional torque source independent of the torque applied to the sample. Summary of the Invention

[0005] In one aspect, an apparatus for measuring the rheological and electrical properties of a sample includes a fixed geometry comprising a double-walled concentric cylinder having a cylindrical axis, an outer wall, an inner wall, and a gap defined between the outer wall and the inner wall. The outer wall and the inner wall are conductive and electrically isolated from each other. The apparatus also includes a movable geometry comprising a cylindrical inner cylinder disposed in the gap and rotatable about the cylindrical axis. The cylindrical inner cylinder is conductive. An outer sample gap is defined between the cylindrical inner cylinder and the outer wall, and an inner sample gap is defined between the cylindrical inner cylinder and the inner wall.

[0006] The device may also include a motor shaft coupled to the cylindrical inner cylinder via an electrically insulating element. The device may additionally include a motor coupled to the motor shaft and a voltage source communicating with the outer wall via a first conductive path and with the inner wall via a second conductive path.

[0007] The outer and inner walls can be fixed to an electrically insulating base, and the electrically insulating base can contain a thermally conductive material. One or more electrodes can be disposed inside the electrically insulating base. A temperature controller can be in thermal communication with the electrically insulating base. Fluid channels can be included through the electrically insulating base and the inner wall to conduct the flow of heat transfer fluid. Fluid channels can be included through the fixed geometry.

[0008] In another aspect, an apparatus for measuring the rheological and electrical properties of a sample includes a movable geometry, a shaft, and a fixed geometry. The movable geometry includes a rotatable plate made of a conductive material and having an electrically insulating hub. The shaft extends from the electrically insulating hub along a rotation axis and is configured to rotate the rotatable plate about the rotation axis. The fixed geometry includes a first fixed plate and a second fixed plate, each made of a conductive material and spaced apart from each other to define a gap. The rotatable plate is disposed in this gap. The first fixed plate has a central opening through which the shaft passes, and the second fixed plate has an electrically insulating hub arranged opposite to the electrically insulating hub of the rotatable plate.

[0009] The device may also include an electrically insulating sidewall disposed circumferentially around the gap and around the outer edge of each of the first and second fixed plates. The electrically insulating sidewall is configured to rotate about the axis of rotation at a wall angular velocity substantially equal to the angular velocity of the rotatable plate.

[0010] The radius of the rotatable plate can be smaller than the radius of the first fixed plate and smaller than the radius of the second fixed plate.

[0011] In another aspect, an apparatus for measuring the rheological and electrical properties of a sample includes a first geometry having a first fixing element and a second fixing element, each of which is conductive and has a surface configured to face the other across a gap. The first fixing element and the second fixing element are electrically isolated from each other. The apparatus also includes a second geometry having a rotatable element disposed in the gap and configured to rotate between the first fixing element and the second fixing element. The rotatable element is conductive such that, in response to the application of a voltage to the first fixing element and the second fixing element, a first electric field is generated between the first fixing element and the rotatable element, and a second electric field is generated between the rotatable element and the second fixing element.

[0012] In another aspect, an apparatus for measuring the rheological and electrical properties of a sample includes a first geometry having a fixing element having a first conductive region and a first surface. The apparatus also includes a second geometry including a rotatable element having a conductive region and a second surface. The second geometry is separated from the first geometry across a gap defined between the first and second surfaces. The first and second conductive regions are arranged opposite to each other across the gap. In response to the application of a voltage to the first and second conductive regions, an electric field is generated between the first and second conductive regions across the gap. Attached Figure Description

[0013] 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.

[0014] Figure 1 This is a diagram of a known rheometer used to measure the rheological and electrical properties of a sample.

[0015] Figure 2 This is a cross-sectional side view of a rheometer with a double-walled cup-shaped measuring geometry according to an embodiment of the present invention.

[0016] Figure 3 This is a cross-sectional side view of another embodiment of a rheometer with a double-walled cup-shaped measuring geometry.

[0017] Figure 4 This is a cross-sectional side view of another embodiment of a rheometer with a double-walled cup-shaped measuring geometry.

[0018] Figure 5 This is a cross-sectional side view of another embodiment of a rheometer with a double-walled cup-shaped measuring geometry.

[0019] Figure 6 This is a cross-sectional side view of a rheometer with a parallel plate measurement geometry according to an embodiment of the present invention.

[0020] Figure 7 This is a cross-sectional side view illustration of another embodiment of a rheometer with a parallel plate measurement geometry.

[0021] Figure 8A and Figure 8B These are simplified cross-sectional side views and vertical views of another embodiment of a rheometer with a concentric cylindrical measuring geometry.

[0022] Figure 9 This is a simplified cross-sectional side view of another embodiment of a rheometer with a concentric cylindrical measurement geometry.

[0023] Figure 10 This is a simplified cross-sectional side view of another embodiment of a rheometer with a concentric cylindrical measurement geometry.

[0024] Figure 11 This is a simplified cross-sectional side view of another embodiment of a rheometer with a concentric cylindrical measurement geometry. Detailed Implementation

[0025] References to embodiments or examples in this specification indicate that a particular feature, structure, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this teaching. References to specific embodiments or examples within this specification do not necessarily refer to the same embodiment or example.

[0026] 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.

[0027] Various terms are used in the following description. As used herein, the term "geometry" refers to one or more components used to generate the desired stress or strain in a sample. For example, for a sample positioned between two horizontally arranged parallel plates, where one plate rotates relative to the other, the rotating plate may be referred to as the moving geometry, and the stationary plate as the stationary geometry. Alternatively, one plate may simply be referred to as the upper geometry, and the other as the lower geometry. Similarly, the geometry is associated with other rheometer arrangements, such as concentric cylinders, where one cylinder remains stationary while the other rotates about its axis.

[0028] As used herein, an "electrode" refers to a conductive element used to establish an electric field between an element and another conductive element. In the examples below, an electrode may guide electrical components, such as the metal plate geometry in a parallel-plate rheometer or part or all of the walls in a double-walled cup measurement geometry.

[0029] Figure 1 This is a schematic diagram of a known rheometer 10 that can be used to measure the rheological and electrical properties of a sample. The rheometer 10 includes a lower fixed geometry 12 on a larger plate or block 14. In some embodiments, thermal control of the sample temperature may be achieved via a thermal controller thermally connected to the lower geometry through the plate 14. The rheometer 10 also includes an upper geometry 16 separated from the lower geometry 12 by a sample gap occupied by the sample 18 to be measured. A shaft 20 couples the upper geometry 16 to a combined motor transducer 22, which is buffered and suspended by air. Current supplied to the motor 22 provides torque to rotate the upper geometry 16, and a displacement sensor 24 provides a means of sensing rotational displacement. For example, the displacement sensor 24 may be an optical encoder and an optical sensor. The flow of motor current is monitored to sense the torque applied to the sample 18.

[0030] To generate an electric field on sample 18, a voltage difference is applied between the lower geometry 12 and the upper geometry 16. This is achieved by electrically coupling the lower geometry 12 to one terminal of a voltage source and electrically coupling the upper moving geometry 16 to another terminal of the voltage source. For example, the contacts used to apply the voltage to the upper geometry 16 may include conductive liquid or sliding friction contacts. Such contacts have their own impedance characteristics, which increases the difficulty of measuring sample impedance and may reduce the signal-to-noise ratio of the sample measurement signal.

[0031] In the rheometer 10 shown, both the lower geometry 12 and the upper geometry 16 are disks; however, it should be understood that other measurement geometry configurations can be similarly used to generate an electric field on the sample 18. For example, the two geometries could be concentric cylindrical walls separated by a sample gap, with one of the cylindrical walls rotating relative to the other. These configurations would also suffer performance degradation due to the presence of electrical contacts on the moving geometry.

[0032] In short, the embodiments and examples disclosed herein relate to an apparatus for measuring the rheological and electrical properties of a sample. The described embodiments relate to a rheometer in which a moving geometry is electrically isolated from a fixed geometry, and a voltage is applied between two fixed components or regions of the rheometer. For example, the fixed components may be two electrically isolating elements of the fixed geometry. For a rheometer with a double-walled electric cup arrangement, the moving geometry occupies a gap between two fixed cylindrical walls, one electrode is defined on the fixed inner wall, and the other electrode is defined on the fixed outer wall. The voltage applied to the electrodes generates an electric field in the gap between the walls containing the sample and the moving geometry. For a rheometer with a parallel plate arrangement, the moving geometry may be a rotatable plate parallel to and positioned between two fixed parallel plates. In this configuration, each electrode is attached to a corresponding one of the fixed and electrically isolating plates, such that a voltage difference can be generated in the gap between the fixed parallel plates containing the sample and the rotatable geometry.

[0033] Advantageously, the measurement data obtained using this device are not adversely affected by the electrodes used to generate an electric field on the sample. The device described herein enables a more accurate determination of the dielectric properties of the sample and how these properties relate to the measured mechanical properties. Measurements can be performed in the following modes: at a single frequency of the applied voltage while varying the shear rate; at a single shear rate while varying the frequency of the applied voltage; or at both the frequency of the applied voltage and the shear rate. These measurements can be performed at a single sample temperature or over a range of temperatures.

[0034] Figure 2 This is a cross-sectional side view of a rheometer 30 with a double-walled cup-shaped measuring geometry. The rheometer 30 includes a fixed outer wall 32 coaxially disposed around a fixed inner wall 34 to define a radial gap between the walls. The two fixed walls 32, 34 are fixed in a base 35 made of an electrically insulating material. As a non-limiting example without considering temperature control, polyetheretherketone (PEEK), acetyl, and other polymeric materials can be used at lower to medium temperatures. At higher temperatures, such as for polymer melt experiments, ceramic insulators can be used. For ease of manufacture, materials such as Macor can be preferred in an oven where temperature control is provided by air convection on the side of the plate.® Ceramics. A protective coating can be applied to any wetted surface of the ceramic to protect the surface from the influence of the sample. The moving geometry is defined by a conductive cylindrical inner cylinder 36, which takes the form of a cylindrical wall disposed in the gap between fixed cylindrical walls 32, 34. The cylindrical wall 36 is electrically isolated relative to the motor shaft 37, for example, by an electrically insulating structure or coupling 38. Since the radial gap is relatively short relative to the edge 40 (bottom portion) of the cylindrical wall 36, and the surface area on the opposing cylindrical walls 32, 34 is significantly larger than the surface area of ​​the edge 40, most of the torque is generated by the sample gap, and the edge effect is generally negligible. Similarly, the conductivity and capacitance in the radial sample gap are larger than those at the edge 40 of the cylindrical wall 36, so the edge effect is generally negligible. Nevertheless, in some applications, it may be desirable to reduce the area of ​​the inner cylinder 36 in the region above the opposing walls 32, 34 to reduce the capacitance, conductivity, and shear area outside the measurement area.

[0035] Electrical wires or other forms of electrical connectors can be fixed to the fixed outer wall 32 and fixed inner wall 34 to couple to corresponding terminals of the voltage source, enabling the application of static or AC voltage across the radial gap. By using only fixed components for the electrodes, electrical measurements do not incur additional torque, thus achieving higher rheological measurement sensitivity. Electrical couplers can be provided on the corresponding fixed components to facilitate the attachment of wires or cables to the voltage source and measuring instrument. Advantageously, electrical measurement sensitivity is improved compared to rheometers where one or more electrodes are in contact with the moving geometry.

[0036] When there is a voltage difference between the outer wall 32 and the inner wall 34, the electric field lines and current flow radially through the sample 42 from the outer wall 32 to the conductive moving cylindrical wall 36 and then to the inner wall 34; or vice versa if the voltage polarities are opposite.

[0037] Rheometer measurements, by simultaneously measuring torque, rotational displacement, and velocity, and the voltage and current flow between electrodes, can directly correlate changes in conductivity and capacitance with changes in shear stress, strain, and strain rate. For example, electrical measurements can use an impedance meter (e.g., an LCR meter) to measure the impedance and / or dielectric properties of a sample by applying an AC voltage to the outer wall 32 and the inner wall 34 and measuring the current at different frequencies.

[0038] Figure 3 A cross-sectional side view of the rheometer 50 is shown, its construction being similar to... Figure 2The rheometer includes an auxiliary electrode 52. The auxiliary electrode 52 is circular and can be maintained at a voltage different from that of the outer wall 32 and the inner wall 34. As shown, the auxiliary electrode 52 is disposed inside the electrically insulating base 35. The auxiliary electrode 52 can be coupled to a reference voltage, which serves as a comparison voltage relative to the voltage used to generate an electric field across the sample gap.

[0039] In some embodiments, one or more of the electrically insulating parts are made of a material with high thermal conductivity, enabling precise control of the sample temperature. For example, a base 62 made of a thermally conductive material can facilitate heat flow between the fixed walls 32, 34 and the external temperature controller 64, such as... Figure 4 As shown. Furthermore, the electrically insulating portion 38 used for the electrically isolated moving geometry can be made of a thermally conductive material, enabling better thermal control of the moving geometry using a temperature controller 64. As a non-limiting example, the thermally conductive materials used for the base 62 and / or the electrically insulating portion 38 include aluminum nitride, alumina, silicon nitride, and other thermally conductive ceramics.

[0040] Figure 5 It shows having with Figure 4 The rheometer is configured similarly to the rheometer 70; however, a temperature controller 64 is absent, and temperature control is performed using a heat transfer fluid. Preferably, the heat transfer fluid is an electrically insulating fluid, such as air or silicone oil. The fluid is received at an inlet port 72 in the electrically insulating base 35' and flows through a fluid channel 74 (as indicated by the arrow) to an outlet port 76. The fluid channel 74 passes through the base 35' and through the inner wall 34', then returns through the base 35' to the outlet port 76. A second fluid channel 78 extending between the inlet port 80 and the outlet port 82 on the outer wall 32' can be used to allow the heat transfer fluid to pass through. It should be understood that alternative channel paths, different from the illustrated channel paths, may be provided within the corresponding components 35', 32', depending on specific heat transfer requirements and manufacturability constraints.

[0041] Figure 6A cross-sectional side view of an example rheometer 90 with a parallel-plate measurement geometry is shown. The first (moving) geometry includes a rotatable plate 92 made of a conductive material and having an electrically insulating hub 94. A shaft 96 extends from the hub 94 along a rotation axis to a motor (not shown) for rotating the plate 92. The second (fixed) geometry includes a pair of parallel plates 100 and 102 that remain fixed during measurement. Each fixed plate 100, 102 is made of a conductive material and is spaced apart from the other plate to define a gap between them. The rotatable plate 92 is disposed in the gap, with the sample occupying the volume of the gap, excluding the volume occupied by the lower ends of the rotatable plate 92 and the shaft 96. The upper fixed plate 100 has a central opening 106 for the shaft 96 to pass through, and the second fixed plate 102 has an electrically insulating hub 108 disposed opposite to the hub 94 on the rotatable plate 92.

[0042] The upper fixed plate 100 is coupled to one terminal of a voltage source, and the lower fixed plate 102 is coupled to the other terminal of a voltage source, allowing a controlled voltage to be applied across the entire sample gap. An intermediate rotatable plate 92 divides the sample gap into a first gap defined between the upper plate 100 and the rotatable plate 92, and a second gap defined between the rotatable plate 92 and the lower plate 102. The radius of the rotatable plate 92 is preferably smaller than the radii of both the upper fixed plate 100 and the lower fixed plate 102 to reduce edge effects. Similarly, the dimensions of the first and second gaps are smaller than the radial dimensions of the fixed plates 100, 102, and the rotatable plate 92 to further reduce edge effects.

[0043] Figure 7 Another example of a rheometer 110 with a parallel-plate measurement geometry is shown. In this example, the rheometer 110 includes a sidewall 112 comprising one or more wall segments circumferentially disposed around an upper fixed plate 100, a lower fixed plate 102, and a sample gap. In some embodiments, the sidewall 112 is configured to rotate about a rotation axis defined by a shaft 96. Preferably, the angular velocity of rotation is approximately the same as the angular velocity of the rotatable plate 92 to minimize any torque generated by the presence of the sidewall 112, which could reduce measurement accuracy. The sidewall 112 is made of an electrically insulating material to maintain electrical isolation between the upper fixed plate 100 and the lower fixed plate 102.

[0044] Additional implementation schemes of the rheometer based on the principles described in this article are as follows: Figures 8A to 11 As shown in the diagram. Each configuration may have unique advantages over the others and may be suitable for specific needs in measuring the rheological and electrical properties of the sample.

[0045] Figure 8A and Figure 8BSimplified cross-sectional side and vertical views are shown, respectively, of another example of a rheometer 120 with a concentric cylindrical measurement geometry. The rheometer 120 is structurally similar to... Figure 2 The rheometer 30; however, instead of applying a voltage difference between the outer and inner walls, a voltage is applied between a first conductive region 122 and a second conductive region 124 of the outer wall 126. More specifically, the first conductive region 122 and the second conductive region 124 are similar in size and arranged diametrically opposite each other. Furthermore, the sample 128 occupies the gap between the outer wall 126 and the inner wall 130 and below the bottom end of the inner wall defined by a flat circular region perpendicular to the cylindrical side surface. A pair of electrically insulating vertical portions of the outer wall 126 separate the two conductive regions 122, 124. Therefore, the circumferential extent of each of the conductive regions 122, 124 is less than 180° around the axis of rotation. When a voltage difference is applied to the two conductive regions 122, 124, the radial direction of the electric field generated between the conductive portion 122 and the inner wall 130 is opposite to the radial direction of the electric field generated between the other conductive portion 124 and the inner wall 126. In this configuration, if the circumferential range of each non-conductive region 132 is smaller than the circumferential range of each conductive region 122, 124, then most of the sample 128 in the cylindrical sample gap is exposed to an electric field region in the electric field region to improve measurement sensitivity.

[0046] Figure 9 A simplified cross-sectional side view of an example rheometer 140 with a concentric cylindrical measurement geometry is shown. The rheometer 140 shown is structurally similar to... Figure 8A and Figure 8B The rheometer 120; however, there are two independent conductive regions 142, 144 in the fixed outer wall 126, each conductive region 142, 144 extending circumferentially a full 360° and vertically separated from the other conductive region by an electrically insulating portion of the outer wall 126. In this configuration, the direction of the electric field generated between the upper conductive region 142 and the inner wall 130 is radially opposite to the direction of the electric field generated between the lower conductive region 144 and the inner wall 130.

[0047] Figure 10 It shows Figure 9A simplified cross-sectional side view of a modified version of the rheometer 140. The rheometer 150 shown includes an inner wall 152 having an electrically insulating ring 154 extending circumferentially 360°. The insulating ring 154 has approximately the same vertical height as the “middle” region of the outer wall 126 (i.e., the region separating the two conductive regions 142, 144). The insulating ring 154 is positioned on the side of the sample 128 opposite to the middle region of the outer wall 126. The portions of the inner wall 152 above and below the insulating ring 154 remain electrically coupled to each other and are therefore at the same voltage. In this arrangement, the radial electric field is better confined to be more parallel to the shear gradient of the sample.

[0048] Figure 11 A simplified cross-sectional side view of another rheometer 160 is shown, which can be considered as... Figure 9 The rheometer 140 is modified. A first conductive region 162 extends 360° around the inner wall 126. A second conductive region 164 is disposed at the bottom of the horizontal portion of the sample 128 in the sample gap. Therefore, an electric field is generated radially on the sample 128 between the first conductive region 162 and the inner wall 130, and a second electric field is generated vertically on the sample 128 at the bottom portion of the sample gap between the second conductive region 164 and the inner wall 130.

[0049] In the various examples described above, a constant shear rate within one or more sample gaps is preferred, but not required. For example, using... Figure 2 The double-walled cup-shaped measuring geometry shown is intended to have the same shear rate between the rotating upper geometry and the outer wall as the shear rate between the rotating upper geometry and the inner wall. (Reference) Figure 2 The rheometer 30 is achieved by controlling the gap size between the fixed outer wall 32 and the cylindrical wall 36, and the gap size between the cylindrical wall 36 and the fixed inner wall 34.

[0050] While various examples have been shown and described, this description is intended to be exemplary and not limiting, 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. For example, it should be understood that conductive and electrically insulating portions are not limited to single parts or portions. For instance, it may be desirable to manufacture such components from more than one part to address manufacturability and usability issues. Furthermore, although the above embodiments include electrically insulating portions, such portions may be replaced by an electrically insulating plating between conductive portions, provided that the conductivity and capacitance of the plating are sufficiently low relative to the sample to not adversely affect the measurements.

Claims

1. An apparatus for measuring the rheological and electrical properties of a sample, the apparatus comprising: A fixed geometry includes a double-walled concentric cylinder having a cylindrical axis, an outer wall, an inner wall, and a gap defined between the outer wall and the inner wall, wherein the outer wall and the inner wall are conductive and electrically isolated from each other. and A movable geometry comprising a cylindrical inner cylinder disposed in the gap and rotatable about the cylindrical axis, wherein the cylindrical inner cylinder is conductive, and wherein an outer sample gap is defined between the cylindrical inner cylinder and the outer wall, and an inner sample gap is defined between the cylindrical inner cylinder and the inner wall.

2. The apparatus according to claim 1 further includes a motor shaft coupled to the cylindrical inner cylinder via an electrically insulating element.

3. The device according to claim 1, wherein the outer wall and the inner wall are fixed to an electrically insulating base.

4. The device according to claim 3, wherein the electrically insulating base comprises a thermally conductive material.

5. The apparatus of claim 2, further comprising a motor coupled to the motor shaft and a voltage source communicating with the outer wall via a first conductive path and with the inner wall via a second conductive path.

6. The apparatus according to claim 3 further includes at least one electrode disposed inside the electrically insulating base.

7. The apparatus according to claim 4 further includes a temperature controller in thermal communication with the electrically insulating base.

8. The apparatus of claim 4 further includes a fluid channel passing through the electrically insulating base and the inner wall and configured to conduct the flow of a heat transfer fluid.

9. The apparatus of claim 4 further includes a fluid channel passing through the fixed geometry.

10. An apparatus for measuring the rheological and electrical properties of a sample, the apparatus comprising: A movable geometry comprising a rotatable plate made of a conductive material and having an electrically insulating hub; A shaft extending from the electrically insulating hub along a rotation axis and configured to allow the rotatable plate to rotate about the rotation axis; and A fixed geometry includes a first fixed plate and a second fixed plate, each made of a conductive material and spaced apart from the other to define a gap between the first fixed plate and the second fixed plate, a rotatable plate disposed in the gap, the first fixed plate having a central opening for the shaft to pass through, and the second fixed plate having an electrically insulating hub arranged opposite to the electrically insulating hub of the rotatable plate.

11. The apparatus of claim 10, further comprising an electrically insulating sidewall disposed circumferentially around the gap and around the outer edge of each of the first fixing plate and the second fixing plate.

12. The apparatus of claim 11, wherein the electrically insulating sidewall is configured to rotate about the axis of rotation at a wall angular velocity substantially equal to the angular velocity of the rotatable plate.

13. The apparatus of claim 10, wherein the radius of the rotatable plate is smaller than the radius of the first fixed plate and smaller than the radius of the second fixed plate.

14. An apparatus for measuring the rheological and electrical properties of a sample, the apparatus comprising: A first geometry includes a first fixing element and a second fixing element, each of the first fixing element and the second fixing element being conductive and having a surface configured to face the other across a gap, the first fixing element and the second fixing element being electrically isolated from each other. and A second geometry includes a rotatable element disposed in the gap and configured to rotate between a first fixed element and a second fixed element. The rotatable element is conductive, wherein a first electric field is generated between the first fixed element and the rotatable element in response to the application of a voltage applied to the first fixed element and the second fixed element, and a second electric field is generated between the rotatable element and the second fixed element.

15. 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 fixing element having a first conductive region and a first surface; and A second geometry includes a rotatable element having a conductive region and a second surface, the second geometry being separated from the first geometry across a gap defined between the first surface and the second surface, wherein the first conductive region and the second conductive region are arranged opposite to each other across the gap, and wherein an electric field is generated between the first conductive region and the second conductive region across the gap in response to the application of a voltage applied between the first conductive region and the second conductive region.

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