Abstract:
A device for levitating a disk including three bottom electrodes situated below the disk and equidistantly around a top circle and three top electrodes situated above the disk, opposite the three bottom electrodes, and situated equidistantly around a bottom circle. Two bottom reference electrodes are situated below the disk, a first bottom reference electrode forming a bottom inner circle on a bottom inner perimeter of the set of three bottom electrodes, a second bottom reference electrode forming a bottom outer circle on a bottom outer perimeter of the set of three bottom electrodes. Two top reference electrodes are situated above the disk, a first top reference electrode forming a top inner circle on a top inner perimeter of the set of three top electrodes, a second top reference electrode forming a top outer circle on a top outer perimeter of the set of three top electrodes. A drive circuit for driving the three bottom electrodes, the three top electrodes, the two bottom reference electrodes, and the two top reference electrodes. A method of levitating a disk includes applying a first plurality of voltages to three bottom electrodes situated below the disk. A second plurality of voltages is applied to three top electrodes situated above the disk and opposite the three bottom electrodes. A third plurality of voltages is applied to two bottom reference electrodes situated below the disk. A fourth plurality of voltages is applied to two top reference electrodes situated above the disk. A fifth plurality of voltages may be applied to side electrodes to rotate the disk.

Description:
FIELD OF THE INVENTION 
     The present invention generally regards the field of sensors. More particularly, the present invention regards a device and method of electrostatically levitating a disk and for using an electrostatic levitated disk as an accelerometer, an angular accelerometer, an angular velocity sensor, and/or a tilt sensor. 
     BACKGROUND INFORMATION 
     Electrostatic forces have been used to levitate objects. Shao Ju Woo, Jong Up Jeon, Toshiro Higuchi, and Andreas Stemmer discuss in their article “Hysteretic Feedback Control of Electrostatic Levitator for Objects Possessing Large Suspension Area-Airgap Ratio” the electrostatic levitation of 4-inch silicon wafers utilizing a one degree of freedom electrostatic levitator. 
     Michael Kraft, et. al., of the University of Southampton discuss in their article “System Level Simulation of an Electrostatically Levitated Disk” (hereinafter Kraft) simulating the levitation of a micromachined disk by using sigma delta feedback control. Kraft discusses using a middle electrode, which is surrounded by four additional electrodes, to control pitch and tilt. The set of electrodes is above and beneath the disk; therefore, there is the need for up to eight control circuits. Kraft measures the distance of the disk. When the disk leaves a designated position, the maximum force is switched on. This will cause the disk to return to the designated position. Since the maximum force is switched on, the disk will leave the designated position moving in the opposite direction. This will cause the opposite voltage to switch on to force the disk to return to designated position under the influence of a force opposing the first force. Therefore, the disk will always receive high force impulses and the mass of the disk is used to hold the movement of the disk low. The mass of the disk may be 1000 ug. In Kraft, if an external force is applied to the disk (acceleration) the frequencies of the force peaks will change, and this is used to measure the external force. 
     Tokimec, Inc. discusses in “Inertia Sensor Performing Measurement with Rotor Levitating in Vacuum” (hereinafter Tokimec) a sensor which is able to measure the angular rate and acceleration. The Tokimec sensor is a free-floating rotational disk made out of Pyrex glass. 
     However, there is a need for a micromechanical device for measuring acceleration, angular acceleration, angular velocity, and/or tilt using an electrostatic levitated disk, with a minimum amount of control circuitry. 
     SUMMARY OF THE INVENTION 
     A device for levitating a disk is provided including three bottom electrodes situated below the disk and situated equidistantly around a top circle. Three top electrodes are provided situated above the disk, opposite the three bottom electrodes, and equidistantly around a bottom circle. Two bottom reference electrodes are situated below the disk. A first bottom reference electrode forms a bottom inner circle on a bottom inner perimeter of the set of three bottom electrodes. A second bottom reference electrode forms a bottom outer circle on a bottom outer perimeter of the set of three bottom electrodes. Two top reference electrodes are situated above the disk. A first top reference electrode forms a top inner circle on a top inner perimeter of the set of three top electrodes. A second top reference electrode forms a top outer circle on a top outer perimeter of the set of three top electrodes. A drive circuit drives the three bottom electrodes, the three top electrodes, the two bottom reference electrodes, and the two top reference electrodes. 
     A method of levitating a disk includes applying a first plurality of voltages to three bottom electrodes situated below the disk. The three bottom electrodes are situated equidistantly around a top circle. A second plurality of voltages is applied to three top electrodes situated above the disk and opposite the three bottom electrodes. The three top electrodes are situated equidistantly around a bottom circle. A third plurality of voltages is applied to two bottom reference electrodes situated below the disk. A first bottom reference electrode forms a bottom inner circle on a bottom inner perimeter of the set of three bottom electrodes and a second bottom reference electrode forming a bottom outer circle on a bottom outer perimeter of the set of three bottom electrodes. A fourth plurality of voltages is applied to two top reference electrodes situated above the disk. A first top reference electrode forms a top inner circle on a top inner perimeter of the set of three top electrodes and a second top reference electrode forms a top outer circle on a top outer perimeter of the set of three top electrodes. 
     A system for levitating a disk is provided including a first electrode situated below the disk, a second electrode situated above the disk and opposite the first electrode, a third electrode situated below the disk, a fourth electrode situated above the disk and opposite the third electrode, a fifth electrode situated below the disk, and a sixth electrode situated above the disk and opposite the fifth electrode. A bottom outer reference electrode is situated below the disk and outside an outer perimeter formed by the first electrode, the third electrode, and the fifth electrode. A bottom inner reference electrode is situated below the disk and inside an inner perimeter formed by the first electrode, the third electrode, and the fifth electrode. A top outer reference electrode is situated above the disk and outside an outer perimeter formed by the second electrode, the fourth electrode, and the sixth electrode. A top inner reference electrode is situated above the disk and inside an inner perimeter formed by the second electrode, the fourth electrode, and the sixth electrode. At least one drive circuit is electrically coupled to the first electrode, the second electrode, the third electrode, the fourth electrode, the fifth electrode, and the sixth electrode. The at least one drive circuit applies a plurality of voltages. The disk includes at least one of a dielectric material and a semiconductor material, and is about planar and about circular. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of the top electrode configuration of an exemplary embodiment of the present invention. 
         FIG. 2  is an elevated cross section view of the exemplary embodiment shown in  FIG. 1  taken along line II—II showing the top and bottom electrode configurations and the levitating disk. 
         FIG. 3  is an edge view schematic diagram of the cross section shown in  FIG. 2  showing the field lines, force lines, and showing circuitry for the reference electrodes. 
         FIG. 4  is a schematic diagram of one half of the schematic diagram shown in FIG.  3  and showing circuitry for controlling the electrodes. 
         FIG. 5  is a schematic diagram showing a plan view of an exemplary embodiment of the present invention with side electrodes for inducing rotation and the circuitry for controlling one pair of side electrodes. 
         FIG. 6  is a schematic diagram showing a plan view of an exemplary embodiment of the present invention with side electrodes for inducing rotation and the circuitry for controlling one pair of side electrodes and showing a design for a disk component for cooperating with the side electrodes to induce disk rotation. 
         FIG. 7  is a flowchart illustrating an exemplary method for levitating and rotating a disk. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary embodiment of the invention may include several features including simplified circuitry and simplified construction. An exemplary embodiment may use a surface micromachining process which may reduce costs and may increase performance.  FIG. 1  is a plan view of top electrode configuration  9  of an exemplary embodiment of the present invention.  FIG. 1  shows outer top reference electrode  10  defining the outer perimeter of a circle. Top electrodes  12 ,  13 ,  14  collectively define a circle within the inside radius of outer top reference electrode  10 . Each of top electrodes  12 ,  13 ,  14  defines a 120 degree angle, although alternative configurations in which each electrode defines an angle greater or less than 120 degrees may be possible. The electrodes may be symmetrical in order that the levitation force is balanced. Three symmetrical electrodes each occupying 60 degrees of arc separated from each other by another 60 degrees of arc is one alternative possible configuration. 
     Inner top electrode  11  lies radially inward from top electrodes  12 ,  13 ,  14 . Top electrode configuration  9  includes all of outer top electrode  10 , inner top electrode  11 , and top electrodes  12 ,  13 ,  14 . Each of outer top electrode  10 , inner top electrode  11 , and top electrodes  12 ,  13 ,  14  is separated from the other electrodes by an airgap, a layer, and/or a film which may be composed of dielectric and/or semiconductor material. Therefore, each of outer top electrode  10 , inner top electrode  11 , and top electrodes  12 ,  13 ,  14  may be electrically isolated. 
       FIG. 2  is a slightly elevated cross section view of the exemplary embodiment shown in  FIG. 1  taken along line II—II and showing top electrode configuration  9 , bottom electrode configuration  8 , and levitating disk  19 .  FIG. 2  shows outer top electrode  10 , inner top electrode  11 , and top electrodes  12 ,  13 . Mirroring these top electrodes are outer bottom electrode  18 , inner bottom electrode  17 , and bottom electrodes  15 ,  16 . Hole  20  lies at the center of levitating disk  19 . A surface MEMS process may be used to produce levitating disk  19 . Levitating disk  19  may be made of any appropriate material. Levitating disk  19  may be produced by MEMS means, and may include Si, SiGe, SiC, a polymer, or any other material. Outer top electrode  10 , inner top electrode  11 , top electrodes  12 ,  13 , outer bottom electrode  18 , inner bottom electrode  17 , and bottom electrodes  15 ,  16  may have low resistance, and the surface may include a conductive layer, for instance a small deposit of metal or doped semiconductor material. 
       FIG. 3  is an edge view schematic diagram of the cross section shown in  FIG. 2  showing central electrostatic field  21 , fringe electrostatic field  22 , force line arrows F 1 , F 2 , F 3 , top electrode configuration  9 , bottom electrode configuration  8 , and levitating disk  19 . The sideward movement in the direction of force line arrow F 1  may be restricted by the effect of the bowing of fringe electrostatic field  22 . As is shown in  FIG. 3 , fringe electrostatic field  22  bows out from the outer edge between outer top electrode  10  and levitating disk  19 , and out from the outer edge between outer bottom electrode  18  and levitating disk  19 . The effect of the bowing of fringe electrostatic field  22  may have a stabilizing effect on the forces on levitating disk  19  in the direction of force line arrow F  1  and in a direction opposite to force line arrow F 1 . 
     The voltages applied to  12 ,  13 ,  15 , and  16  may be a high frequency alternating voltage. This high frequency alternating voltage may vary continuously, as a sinusoid function, or may vary as a rectangular step function. Both the frequency and the maximum voltage may vary to induce the levitation and counteract the external forces on levitating disk  19 . Sinusoidal high frequency generators  23  and  24  may be driven by a high frequency signal, which may have a phase shift of 180 degrees. The use of a high frequency signal to hold levitating disk  19  horizontally may allow cancellation of forces perpendicular to levitating disk  19 , making regulation of levitating disk  19  position easier. By using a high frequency signal, central electrostatic field  21  and fringe electrostatic field  22  may generate forces in the direction of force line arrows F 1 , F 2 , and F 3 . Force line arrows F 2  and F 3  may cancel each other out, whether levitating disk  19  is in a central position or not. Force line arrow F 1  may depend on the lateral position of levitating disk  19  relative to top electrode configuration  9  and bottom electrode configuration  8 . Force line arrow F 1  may act on both sides of levitating disk  19  and the resulting component may hold levitating disk  19  in a stable horizontal position. The usage of the inner electrodes  11 ,  17  could increase the horizontal stability of the levitated disk. The use of two reference electrodes and three driving electrodes on each side may reduce the number of control circuits necessary to induce stable levitation of levitating disk  19 . 
     Analog driving signals may be used, in the form of a delta sigma controller, where the driving voltages may be periodically switched on and off, applying periodically the maximum force in the opposite direction. The inertia of the mass of levitating disk  19  may be used to average the forces over time. For surface micromachined disks the mass may be so small that high frequencies may be necessary to suppress the vibration due to the alternating forces, and may require a frequency higher than about 50 MHz. 
     The electric potential between the top and bottom electrodes may be high frequency AC voltage. The voltage may vary continuously as a sinusoid signal, or may alternatively be a rectangular signal. This voltage may only change if it is necessary to counteract external forces, e.g. due to acceleration. The value of the voltage may be used to extract a measurement signal to determine if any increase or decrease in the voltage is necessary to maintain levitating disk  19  in a position of equilibrium. This may make it possible to control, and therefore measure, several degrees of freedom of levitating disk  19 . 
     Outer bottom electrode  18 , outer top electrode  10 , inner top electrode  11 , and inner bottom electrode  17  may have an HF voltage, with the voltage in each electrode phase shifted by 180 degrees with respect to each other. Since the alternating current has a 180 degree phase shift with respect to the other, a high frequency current may flow between outer bottom electrode  18  and outer top electrode  10  and/or between inner top electrode  11  and inner bottom electrode  17 . This current may establish fringe electrostatic field  22  shown in FIG.  3 . Fringe electrostatic field  22  may not influence levitating disk  19  with respect to the levitation. Two forces, F 2  and F 3 , may act on levitating disk  19 . F 2  and F 3  may depend on the voltage between levitating disk  19  and outer top electrode  10 , inner top electrode  11 , outer bottom electrode  18 , and inner bottom electrode  17 . This voltage may depend linearly on the gap between levitating disk  19  and outer top electrode  10 , inner top electrode  11 , outer bottom electrode  18 , and inner bottom electrode  17 . A bigger gap may indicate a lower electrical field which leads to a smaller electrical force. The resulting force may be approximately the inverse of the gap squared. Therefore, the forces F 2  and F 3  may null each other. Fringe electrostatic field  22  may maintain levitating disk  19  horizontally in place, since the symmetries of fringe electrostatic field  22  may be destroyed if levitating disk  19  moves out of the field (in the direction of F 1 ). Therefore, the voltages at outer bottom electrode  18 , outer top electrode  10 , inner top electrode  11 , and inner bottom electrode  17  may be HF with a 180 degree phase shift. 
       FIG. 4  illustrates the arrangement for outer top electrode  10 , inner top electrode  11 , top electrode  12 , outer bottom electrode  18 , inner bottom electrode  17 , and bottom electrode  15  in relation to levitating disk  19 .  FIG. 4  is a schematic diagram of one half of the schematic diagram shown in FIG.  3  and shows circuitry controlling the electrodes. To measure yaw rate, levitating disk  19  may need to be set rotating. By rotating levitating disk  19 , additional movement of levitating disk  19  may be induced due to the gyroscopic principle. Rotation may be accomplished by applying a rotating signal to the electrodes of the top electrode configuration (including top electrode  12 ) and the electrodes of the bottom electrode configuration (including bottom electrode  15 ). The electrodes of the top electrode configuration may be paired with the electrodes of the bottom configuration. Each top electrode may be paired with the bottom electrode which is situated opposite the top electrode. In this manner, the electrodes may be divided into 3 pairs. The input signal of the 3 pairs may be the same sinusoid signal, but with each signal shifted by 120-degree with the adjacent electrodes. One electrode may lead by 120 degrees while the other adjacent electrode may lag by 120 degrees. Referring to  FIG. 1 , top electrode  12  may lead top electrode  13  by 120 degrees, while top electrode  12  may lag top electrode  14 . The corresponding bottom electrodes may be driven by voltages having a similar phase relationship. The voltage signals may all be sinusoidal and may be of equal strength. This voltage pattern may generate a dragging force, which may initiate and/or maintain a rotation of levitating disk  19 . In this manner, the induced rotation of the system may operate on a principle similar to that of a step motor and/or a three-phase induction motors. 
     Also shown in  FIG. 4  is position sensing/controlling unit  26 , which may be connected to top electrode  12  by voltage regulator  27  and resistor unit  28 . Also connected to top electrode  12  may be feedback current measuring unit  29 , which may also be connected to position sensing/controlling unit  26 . This may function as a feedback loop, allowing position sensing/controlling unit to determine the distance between top electrode  12  and levitating disk  19  and to thereby adjust the voltage applied to voltage regulator  27 . Similarly, position sensing/controlling unit  26  may be connected to bottom electrode  15  by voltage regulator  30 , which may be an inverter, and resistor unit  28 . The inversion function of voltage regulator  30  may shift the high frequency alternating current by 180 degrees. Also connected to bottom electrode  15  may be feedback current measuring unit  32 , which may also be connected to position sensing/controlling unit  26 . This may also function as a feedback loop, allowing position sensing/controlling unit to determine the distance between top electrode  12  and levitating disk  19  and to thereby adjust the voltage applied to voltage regulator  30 . Outer top electrode  10 , inner top electrode  11 , inner bottom electrode  17 , and outer bottom electrode  18  may all be reference electrodes which may include separate ground connections or may have a common ground. In alternative exemplary embodiments, voltage regulator  27  and voltage regulator  30  may be current regulators, and feedback current measuring unit  29  and feedback current measuring unit  32  may be feedback voltage measuring units. 
     In an exemplary embodiment, each of three top electrodes  12 ,  13 ,  14  and two bottom electrodes  15 ,  16 , and a bottom electrode in the foreground may have a drive circuit similar to that described above and also connected to the same or a different position sensing/controlling unit  26 . Therefore, there may be six drive circuits connected to position sensing/controlling unit  26 . In an alternative exemplary embodiment, outer top electrode  10 , inner top electrode  11 , outer bottom electrode  18 , and/or inner bottom electrode  17  (collectively known as the reference electrodes) may each have a dedicated drive circuitry for providing the high frequency voltage or may have a common drive circuitry. Additionally, the drive circuitry for the reference electrodes may or may not be connected to position sensing/controlling unit  26 . 
     The HF may be lead through top electrode  12  and bottom electrode  15 , resulting in two HF currents (the current flowing through feedback current measuring unit  29  and the current flowing through feedback current measuring unit  32  in FIG.  4 ), where the difference of this currents will correspond to the position of levitating disk  19 . A smaller and thinner levitating disk  19  may be possible with an exemplary embodiment of the present invention. Levitating disk  19  may have a low mass. Therefore, it may be preferable to have very high frequencies to reduce vibrations on the small mass of levitating disk  19 . 
     In another exemplary embodiment, a DC voltage may be used to keep levitating disk  19  in position. The DC voltage may only change if it is necessary, for instance to counteract an external force. For this purpose, the DC voltage may have to change quickly. In another exemplary embodiment, a fixed frequency may be used and the amplitude of the voltage may be varied. In this case for example, a high frequency of about 500 MHz may be used to detect the position of levitating disk  19 . A frequency of about 1 GHz may be used to drive top electrode  12  and bottom electrode  15  using voltage regulator  27  and voltage regulator  30 . The amplitude of the voltages generated by voltage regulator  27  and voltage regulator  30  may then be responsible for the resulting force. 
     A frequency of about 1 GHz may be used to measure the position with respect to outer top electrode  10 , inner top electrode  11 , outer bottom electrode  18 , and/or inner bottom electrode  17 . A small voltage of 50 MHz may be applied to levitating disk  19  using voltage regulator  27  and/or voltage regulator  30 , with a phase shift of 180 degrees. This may cause levitating disk  19  to vibrate at a frequency of 50 MHz. This movement may modulate the currents flowing through feedback current measuring unit  29  and/or feedback current measuring unit  32 . After demodulation of the currents flowing through feedback current measuring unit  29  and/or feedback current measuring unit  32 , the difference of the currents may contain the position information. This information may be used to generate the necessary force to keep the levitating disk  19  in place by driving levitating disk  19  by: increasing the amplitude of the 1 GHz, the 50 MHz, or another frequency (possibly depending on the direction of force); superimposing another voltage at another frequency on any existing HF voltage; and/or superimposing an additional DC voltage. Alternative exemplary embodiments may use variations on the frequency and strength of the voltages and the weight and configuration of levitating disk  19  in order to enable a stable and reliable system. The voltages applied to outer top electrode  10 , inner top electrode  11 , outer bottom electrode  18 , and/or inner bottom electrode  17  may be a HF reference voltage and may generate the levitating force. 
       FIG. 5  is a schematic diagram showing a plan view of an exemplary embodiment of the present invention including side electrodes  33 ,  34 ,  35 ,  36 ,  37 , and  38  for inducing rotation in levitating disk  19  and electric circuitry for controlling the pair of side electrodes  33  and  34 . Placing side electrodes  33 ,  34 ,  35 ,  36 ,  37 , and  38  around the outside of levitating disk  19  may avoid problems associated with differences in the rotation speed of levitating disk  19  and the applied electrical field. Additionally, using side electrodes  33 ,  34 ,  35 ,  36 ,  37 , and  38  to induce rotation may avoid the problem of the variation of the field voltage leading to additional out-of-plane forces, which may lead to unstable rotation, e.g. rolling. Controlling side electrodes  33  and  34  may be circuitry including voltage regulators  40  and  41 , high frequency voltage signal generator  39 , and ground  25 . Voltage regulator  41  may function as an inverter with respect to voltage regulator  40 , causing the voltage applied to side electrode  34  to lead (or alternatively to lag) the sinusoidal voltage applied to side electrode  33  via voltage regulator  40  by 180 degrees. Alternatively, voltage regulator  41  may induce a different lead or lag in the voltage applied to side electrode  34 . Side electrode  35  may be similarly matched with side electrode  36  with a similar set of voltage regulators providing the same or a different lead/lag relationship, and may be connected to the same high frequency voltage signal generator  39 , or alternatively to a different high frequency voltage signal generator. Similarly, side electrodes  37  and  38  may be matched and driven in the same or in a different manner to provide a rotational force on levitated disk  19 . Alternative electrode configurations, including more or fewer electrodes, arranged in matching sets or singly, are possible. 
       FIG. 6  is a schematic diagram showing a plan view of an exemplary embodiment of the present invention with side electrodes  33 ,  34 ,  35 ,  36 ,  37 , and  38  for inducing rotation and electric circuitry for controlling one pair of side electrodes  33  and  34 . Also shown in  FIG. 6  is an alternative exemplary embodiment of a levitating disk  19 . Levitating disk  19  is for cooperating with side electrodes  33 ,  34 ,  35 ,  36 ,  37 , and  38  for inducing levitating disk  19  to rotate. The use of a high frequency signal to drive side electrodes  33 ,  34 ,  35 ,  36 ,  37 , and  38  may allow stable rotation and control of the rotation speed, which may result in greater control of, and/or sensitivity to, the gyroscopic effect. A rotating disk may be used for yaw rate measurements. Unwanted forces may be nulled by using high frequency driving signals with a phase shift of 180 degrees. With a specific design, the movement of levitating disk  19  may be stepped, resulting in precise control of the rotation speed of levitating disk  19 . The sensitivity of the sensor may be adjusted by changing the rotation speed. Levitating disk  19  may be free and extensions  42 ,  43 ,  44 ,  45 ,  46  may be attached directly to levitating disk  19  by beams  48 ,  49 ,  50 ,  51 ,  52 . Levitating disk  19  may include central disk region  47  as well as side interactors  42 ,  43 ,  44 ,  45 , and  46 . These side interactors may be composed of the same material as central disk region  47  or a different material. Beams  48 ,  49 ,  50 ,  51 ,  52  may enable the field for rotating the disk to avoid interference with the field for levitating the disk and the field for maintaining the horizontal position of the disk. Levitating disk  19  may be directly between outer top electrode  10 , inner top electrode  11 , outer bottom electrode  18 , and/or inner bottom electrode  17 , (shown in  FIG. 3 ) and extensions  42 ,  43 ,  44 ,  45 ,  46  may extend outward, as viewed from above, of outer top electrode  10 , inner top electrode  11 , outer bottom electrode  18 , and/or inner bottom electrode  17 . 
       FIG. 7  is a flowchart illustrating an exemplary method for levitating and rotating a disk. The exemplary method starts in Circle  71  and proceeds to Action  72  in which three pairs of electrodes are provided, each pair of electrodes having a top electrode and a bottom electrode. From Action  72 , the flow proceeds to Action  73 , where two reference electrodes are provided on an inner perimeter and an outer perimeter of the top electrodes, and two reference electrodes are provided on an inner perimeter and an outer perimeter of the bottom electrodes. From Action  73 , the flow proceeds to Action  74 , a semiconductor or dielectric disk is arranged between each pair of electrodes. From Action  74 , the flow proceeds to Action  75 , where voltages are applied to the three pairs of electrodes. From Action  75 , the flow proceeds to Action  76 , where a position of the disk is measured by measuring a voltage or a current at the electrode. From Action  76 , the flow proceeds to Action  77 , where the voltages are adjusted at the electrodes to maintain a neutral position of the disk and to counteract external forces. From Action  77 , the flow proceeds to Decision  78 , where the query is posed whether the system has rotational capabilities. If the response to the query of Decision  78 , is in the affirmative, the flow proceeds to Action  79 , where side electrodes are provided situated in the plane of the disk and around an outer perimeter of the disk. From Action  79 , the flow proceeds to Action  80 , where voltages are applied to the side electrodes in sequence to induce a rotational force on the disk. From Action  80 , the flow proceeds to Endpoint  81 . If the response to the query of Decision  78 , is in the negative, the flow proceeds to Endpoint  81 . 
     A device and method of electrostatically levitating a disk and for using an electrostatic levitated disk as an accelerometer, an angular accelerometer, an angular velocity sensor, and/or a tilt sensor is provided herein. While several embodiments have been discussed, others, within the invention&#39;s spirit and scope, are also plausible.