MEMS-based sensor for lubricant analysis

• US 20060105467A1
• Filed: 11/12/2004
• Published: 05/18/2006
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Predict, Inc.
• Original Assignee: Predict, Inc.
• Inventors: Niksa, Andrew J., Fousek, James D.
• Granted Patent: US 7,541,004 B2
• Time in Patent Office: Days
• US Class Current: 436/150
• CPC Class Codes: G01N 27/126 comprising organic polymers

Abstract

A fluid contamination analyzer employs one or more MEMS-based sensors. The sensors are incorporated into probes or alternatively may be employed in an in-line analyzer residing in the fluid. The sensors, which can be selective to detect a distinct contaminant within the fluid, sense an impedance of the fluid, which is a function of its contamination and communicates the impedance to analysis circuitry.

Claims

1. A fluid contamination analyzer, comprising:

at least one sensor, wherein the at least one sensor includes;

a substrate;

a plurality of electrodes formed over the substrate; and

a contaminant selective layer disposed adjacent at least one of (i) the electrodes or (ii) the substrate, said layer being selective to attract a predetermined contaminant within the fluid;

wherein when a fluid contacts the sensor an impedance of the fluid may be determined using the electrodes of the sensor, thereby providing an indication of fluid contamination.

2. The fluid contamination analyzer according to claim 1, wherein the contaminant selective layer comprises an intermediate layer disposed between the electrodes and the substrate.

3. The fluid contamination analyzer according to claim 2, wherein the contaminant selective layer is a low-K dielectric material.

4. The fluid contamination analyzer according to claim 3, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

5. The fluid contamination analyzer according to claim 1, wherein the contaminant selective layer comprises a top layer disposed over the electrodes.

6. The fluid contamination analyzer according to claim 5, wherein the contaminant selective layer is a low-K dielectric material.

7. The fluid contamination analyzer according to claim 6, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

8. The fluid contamination analyzer according to claim 1, wherein the contaminant selective layer is selected from the group consisting of silicon nitride, silicon dioxide, cerium dioxide, glass, quartz, aluminum oxide, aluminum nitride, boron nitride, titanium nitride, gallium nitride, diamond, diamond like carbon, silicon carbide, parylene, epoxy, polyimide, polycarbonate, polyester, and polyphenylene sulfide.

9. The fluid contamination analyzer according to claim 1, wherein the electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel, copper and silver.

10. The fluid contamination analyzer according to claim 1, wherein the plurality of electrodes are interdigitated.

11. The fluid contamination analyzer according to claim 10, wherein a spacing between adjacent electrodes is between about 1 micron to about 250 microns.

12. The fluid contamination analyzer according to claim 10, wherein a spacing between adjacent electrodes is less than 1 micron.

13. The fluid contamination analyzer according to claim 1, further comprising a temperature sensor for measuring a temperature of the fluid in contact with the sensor.

14. The fluid contamination analyzer according to claim 13, wherein the temperature of the fluid is used to compensate the impedance measurement of the fluid.

15. The fluid contamination analyzer according to claim 13, wherein the temperature sensor is selected from the group consisting of a thermocouple, a thermistor and a resistance temperature detector (RTD).

16. The fluid contamination analyzer according to claim 13, wherein data is communicated to a remote monitoring device through a communications link.

17. The fluid contamination analyzer according to claim 16, wherein the communications link is a wireless communications link.

18. The fluid contamination analyzer according to claim 1, further comprising a non-volatile memory module for storing data.

19. The fluid contamination analyzer of according to claim 18, wherein the data stored in the non-volatile memory module is at least one of a customer name, a serial number of the sensor, a manufacture date of the sensor, a calibration factor of the sensor, a temperature of the fluid, a sensor type, a location of sensor, a maintenance date of sensor, a selected reference oil, or an impedance of the fluid.

20. The fluid contamination analyzer according to claim 18, wherein the non-volatile memory module is an electrically erasable programmable read only memory module (EEPROM).

21. The fluid contamination analyzer according to claim 1, further comprising a temperature sensor for measuring a temperature of the fluid in contact with the sensor and a non-volatile memory module for storing data.

22. The fluid contamination analyzer according to claim 1, further comprising a plate electrode disposed over the at least one MEMS based sensor, wherein when a fluid is disposed between the plate electrode and the at least one MEMS based sensor an impedance of the fluid is determined using the plate electrode and at least one electrode of the at least one MEMS based sensor or the plurality of electrodes of the MEMS based sensor, thereby providing an indication of fluid contamination.

23. The fluid contamination analyzer according to claim 22, further comprising an electrostatic field control circuit electrically coupled to the plate electrode, wherein the electrostatic field control circuit develops an electrostatic field between the plate electrode and the plurality of electrodes, thereby dislodging with an electrostatic force any particulates that may have become stuck within the sensor due to static charge on the particulates.

24. The fluid contamination analyzer according to claim 22, further comprising:

a plurality of switches, including

a first switch operatively coupled to a first electrode of the plurality of electrodes;

a second switch operatively coupled to a second electrode of the plurality of electrodes;

a third switch operatively coupled to the plate electrode; and

a fourth switch operatively coupled to the first electrode and the second electrode.

25. The fluid contamination analyzer according to claim 24, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance between the plate electrode and at least one electrode of the at least one MEMS based sensor.

26. The fluid contamination analyzer according to claim 24, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance of the fluid between and adjacent to the electrodes of the MEMS based sensor.

27. The fluid contamination analyzer according to claim 24, wherein the plurality of switches are MEMS switches.

28. The fluid contamination analyzer according to claim 24, wherein the plurality of switches are formed on the substrate of the MEMS based sensor.

29. The fluid contamination analyzer according to claim 22, wherein the plate electrode and the plurality of electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel, copper and silver.

30. The fluid contamination analyzer according to claim 22, wherein the plate electrode is about 1 micron to about 10,000 microns thick.

31. The fluid contamination analyzer according to claim 22, wherein the plate electrode is substantially parallel to a top surface of the at least one MEMS based sensor.

32. The fluid contamination analyzer according to claim 1, wherein the substrate is the contaminant selective layer.

33. The fluid contamination analyzer of claim 1, wherein the sensor is a MEMS based sensor.

34. The fluid contamination analyzer of claim 1, wherein the substrate is at least one of a glass substrate or a quartz substrate.

35. The fluid contamination analyzer of claim 1, wherein the plurality of electrodes have a width between about 1 micron to about 50 microns.

36. The fluid contamination analyzer of claim 1, further comprising a selectively activatable electromagnet in proximity to the at least one sensor, wherein the magnet may be activated and deactivated in response to control signals and provides a magnet gradient across the at least one sensor, wherein the magnet gradient provides a contaminant distribution across the at least one sensor.

37. The fluid contamination analyzer according to claim 1, wherein the contaminated selective layer is an insulator.

38. An in-line fluid contamination analyzer, comprising:

an array of MEMS-based sensors located within a fluid, wherein each sensor includes a substrate, a plurality of electrodes formed over the substrate, and a contaminant-selective layer disposed adjacent the electrodes, said array including;

a first MEMS-based sensor having a first contaminant-selective layer which is selective to attract a first contaminant within the fluid;

a second MEMS-based sensor having a second contaminant-selective layer which is selective to attract a second contaminant within the fluid; and

a third MEMS-based sensor having a third contaminant-selective layer which is selective to attract a third contaminant within the fluid;

wherein each sensor is operative to determine an impedance of the fluid contacting each sensor, thereby providing an indication of fluid contamination.

39. The fluid contamination analyzer according to claim 38, wherein the contaminant selective layer comprises an intermediate layer disposed between the electrodes and the substrate.

40. The fluid contamination analyzer according to claim 39, wherein the contaminant selective layer is a low-K dielectric material.

41. The fluid contamination analyzer according to claim 40, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

42. The fluid contamination analyzer according to claim 38, wherein the contaminant selective layer comprises a top layer disposed over the electrodes.

43. The fluid contamination analyzer according to claim 42, wherein the contaminant selective layer is a low-K dielectric material.

44. The fluid contamination analyzer according to claim 43, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

45. The fluid contamination analyzer according to claim 38, wherein the contaminant selective layer is selected from the group consisting of silicon nitride, silicon dioxide, cerium dioxide, glass, quartz, aluminum oxide, aluminum nitride, boron nitride, titanium nitride, gallium nitride, diamond, diamond like carbon, silicon carbide, parylene, epoxy, polyimide, polycarbonate, polyester, and polyphenylene sulfide.

46. The fluid contamination analyzer according to claim 38, wherein the electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel and silver.

47. The fluid contamination analyzer according to claim 38, wherein the plurality of electrodes are interdigitated.

48. The fluid contamination analyzer according to claim 47, wherein a spacing between adjacent electrodes is between about 1 micron to about 250 microns.

49. The fluid contamination analyzer according to claim 47, wherein a spacing between adjacent electrodes is less than 1 micron.

50. The fluid contamination analyzer according to claim 38 further comprising a temperature sensor for measuring a temperature of the fluid in contact with the sensor.

51. The fluid contamination analyzer according to claim 50, wherein the temperature of the fluid is used to compensate the impedance measurement of the fluid.

52. The fluid contamination analyzer according to claim 50, wherein the temperature sensor is selected from the group consisting of a thermocouple, a thermistor and a resistance temperature detector (RTD).

53. The fluid contamination analyzer according to claim 50, wherein temperature data and/or sensor data is communicated to a remote monitoring device through a communications link.

54. The fluid contamination analyzer according to claim 53, wherein the communications link is a wireless communications link.

55. The fluid contamination analyzer according to claim 38, further comprising a non-volatile memory module for storing data.

56. The fluid contamination analyzer of according to claim 55, where the data stored to the non-volatile memory module is at least one of a customer name, a serial number of the sensor, a manufacture date of the sensor, a calibration factor of the sensor, a temperature of the fluid, a sensor type, a location of sensor, a maintenance date of the sensor, a selected reference oil, or an impedance of the fluid.

57. The fluid contamination analyzer according to claim 55, wherein the non-volatile memory module is an electrically erasable programmable read only memory module (EEPROM).

58. The fluid contamination analyzer according to claim 38, further comprising a temperature sensor for measuring a temperature of the fluid in contact with the sensor and a non-volatile memory module for storing data.

59. The fluid contamination analyzer according to claim 38, further comprising a plate electrode disposed over at least one MEMS based sensor, wherein when a fluid is disposed between the plate electrode and the at least one MEMS based sensor an impedance of the fluid is determined using the plate electrode and at least one electrode of the at least one MEMS based sensor or the plurality of electrodes of the MEMS based sensor, thereby providing an indication of fluid contamination.

60. The fluid contamination analyzer according to claim 59, further comprising:

a plurality of switches, including

a first switch operatively coupled to a first electrode of the plurality of electrodes;

a second switch operatively coupled to a second electrode of the plurality of electrodes;

a third switch operatively coupled to the plate electrode; and

a fourth switch operatively coupled to the first electrode and the second electrode.

61. The fluid contamination analyzer according to claim 60, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance between the plate electrode and at least one electrode of the at least one MEMS based sensor.

62. The fluid contamination analyzer according to claim 60, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance of the fluid between and adjacent to the electrodes of the MEMS based sensor.

63. The fluid contamination analyzer according to claim 60, wherein the plurality of switches are MEMS switches.

64. The fluid contamination analyzer according to claim 60, wherein the plurality of switches are formed on the substrate of the MEMS based sensor.

65. The fluid contamination analyzer according to claim 59, wherein the plate electrode and the plurality of electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel, copper and silver.

66. The fluid contamination analyzer according to claim 59, wherein the plate electrode is about 1 micron to about 10,000 microns thick.

67. The fluid contamination analyzer according to claim 59, wherein the plate electrode is substantially parallel to a top surface of the at least one MEMS based sensor.

68. The fluid contamination analyzer of claim 38, wherein the substrate is at least one of a glass substrate or a quartz substrate.

69. The fluid contamination analyzer of claim 38, wherein the plurality of electrodes have a width between about 1 micron to about 50 microns.

70. The fluid contamination analyzer of claim 38, further comprising a selectively activatable electromagnet in proximity to the array of MEMS-based sensors, wherein the magnet may be activated and deactivated in response to control signals and provides a magnet gradient across the array of MEMS-based sensors, wherein the magnet gradient provides a contaminant distribution across the array of MEMS based sensors.

71. A fluid contamination analyzer, comprising:

a reference MEMS-based sensor disposed within a reference housing, said reference housing containing a substantially contaminant-free volume of the fluid being analyzed; and

a plurality of sample MEMS-based sensors disposed adjacent the reference housing within a fluid.

72. The fluid contamination analyzer according to claim 71, wherein the reference sensor and the sample sensor further comprise:

a substrate;

a plurality of electrodes formed over the substrate; and

a contaminant selective layer disposed adjacent at least one of (i) the electrodes or (ii) the substrate, said layer being selective to attract a predetermined contaminant within the fluid;

wherein when a fluid contacts the sensor an impedance of the fluid may be determined using the electrodes of the sensor, thereby providing an indication of fluid contamination.

73. The fluid contamination analyzer according to claim 72, wherein the contaminant selective layer comprises an intermediate layer disposed between the electrodes and the substrate.

74. The fluid contamination analyzer according to claim 73, wherein the contaminant selective layer is a low-K dielectric material.

75. The fluid contamination analyzer according to claim 74, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

76. The fluid contamination analyzer according to claim 72, wherein the contaminant selective layer comprises a top layer disposed over the electrodes.

77. The fluid contamination analyzer according to claim 76, wherein the contaminant selective layer is a low-K dielectric material.

78. The fluid contamination analyzer according to claim 77, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

79. The fluid contamination analyzer according to claim 72, wherein the contaminant selective layer is selected from the group consisting of silicon nitride, silicon dioxide, cerium dioxide, glass, quartz, aluminum oxide, aluminum nitride, boron nitride, titanium nitride, gallium nitride, diamond, diamond like carbon, silicon carbide, parylene, epoxy, polyimide, polycarbonate, polyester, and polyphenylene sulfide.

80. The fluid contamination analyzer according to claim 72, wherein the electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel, copper and silver.

81. The fluid contamination analyzer according to claim 72, wherein the plurality of electrodes are interdigitated.

82. The fluid contamination analyzer according to claim 81, wherein a spacing between adjacent electrodes is between about 1 micron to about 250 microns.

83. The fluid contamination analyzer according to claim 81, wherein a spacing between adjacent electrodes is less than 1 micron.

84. The fluid contamination analyzer according to claim 71, further comprising at least one temperature sensor for measuring a temperature of the fluid in contact with the reference sensor and/or sample sensors.

85. The fluid contamination analyzer according to claim 84, wherein the temperature of the fluid is used to compensate the impedance measurement of the fluid.

86. The fluid contamination analyzer according to claim 84, wherein the temperature sensor is selected from the group consisting of a thermocouple, a thermistor and a resistance temperature detector (RTD).

87. The fluid contamination analyzer according to claim 84, wherein temperature data and/or sensor data is communicated to a remote monitoring device through a communications link.

88. The fluid contamination analyzer according to claim 87, wherein the communications link is a wireless communications link.

89. The fluid contamination analyzer according to claim 71, further comprising a non-volatile memory module for storing data.

90. The fluid contamination analyzer of according to claim 89, wherein the data stored in the non-volatile memory module is at least one of a customer name, a serial number of the sensor, a manufacture date of the sensor, a calibration factor of the sensor, a temperature of the fluid, a sensor type, a location of sensor, a maintenance date of the sensor, a selected reference oil, or an impedance of the fluid.

91. The fluid contamination analyzer according to claim 89, wherein the non-volatile memory module is an electrically erasable programmable read only memory module (EEPROM).

92. The fluid contamination analyzer according to claim 71, further comprising a temperature sensor for measuring a temperature of the fluid in contact with the sensor and a non-volatile memory module for storing data.

93. The fluid contamination analyzer according to claim 71, further comprising a plate electrode disposed over the reference sensor and/or at least one sample sensor of the plurality of sample sensors, wherein when a fluid is disposed between the plate electrode and the MEMS based sensors an impedance of the fluid is determined using the plate electrode and at least one electrode of the MEMS based sensors or a plurality of electrodes of the MEMS based sensor, thereby providing an indication of fluid contamination.

94. The fluid contamination analyzer according to claim 93, further comprising:

a plurality of switches, including

a first switch operatively coupled to a first electrode of the plurality of electrodes;

a second switch operatively coupled to a second electrode of the plurality of electrodes;

a third switch operatively coupled to the plate electrode; and

a fourth switch operatively coupled to the first electrode and the second electrode.

95. The fluid contamination analyzer according to claim 94, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance between the plate electrode and at least one electrode of the at least one MEMS based sensor.

96. The fluid contamination analyzer according to claim 94, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance of the fluid between and adjacent to the electrodes of the MEMS based sensor.

97. The fluid contamination analyzer according to claim 94, wherein the plurality of switches are MEMS switches.

98. The fluid contamination analyzer according to claim 94, wherein the plurality of switches are formed on the substrate of the MEMS based sensor.

99. The fluid contamination analyzer according to claim 94, wherein the plate electrode and the plurality of electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel, copper and silver.

100. The fluid contamination analyzer according to claim 93, wherein the plate electrode is about 1 micron to about 10,000 microns thick.

101. The fluid contamination analyzer according to claim 93, wherein the plate electrode is substantially parallel to a top surface of the at least one MEMS based sensor.

102. The fluid contamination analyzer of claim 72, wherein the substrate is at least one of a glass substrate or a quartz substrate.

103. The fluid contamination analyzer of claim 72, wherein the plurality of electrodes have a width between about 1 micron to about 50 microns.

104. The fluid contamination analyzer of claim 71, further comprising a selectively activatable electromagnet in proximity to the sample sensors, wherein the magnet may be activated and deactivated in response to control signals and provides a magnet gradient across the sample sensors, wherein the magnet gradient provides a contaminant distribution across the sample sensors.

105. A fluid contamination analyzer, comprising:

at least one MEMS-based sensor, said at least one sensor including;

a substrate;

a plurality of conductors formed over the substrate; and

a local heater disposed adjacent the at least one MEMS-based sensor, said local heater providing a temperature gradient through which the fluid is run;

wherein the conductors form electrodes of the sensor and when a fluid contacts the sensor an impedance of the fluid may be determined as a function of temperature, thereby providing an indication of fluid contamination.

106. The fluid contamination analyzer according to claim 105, wherein the sensors further comprise a contaminant selective layer disposed adjacent at least one of (i) the electrodes or (ii) the substrate, said layer being selective to attract a predetermined contaminant within the fluid.

107. The fluid contamination analyzer according to claim 106, wherein the contaminant selective layer comprises an intermediate layer disposed between the electrodes and the substrate.

108. The fluid contamination analyzer according to claim 107, wherein the contaminant selective layer is a low-K dielectric material.

109. The fluid contamination analyzer according to claim 108, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

110. The fluid contamination analyzer according to claim 106, wherein the contaminant selective layer comprises a top layer disposed over the electrodes.

111. The fluid contamination analyzer according to claim 110, wherein the contaminant selective layer is a low-K dielectric material.

112. The fluid contamination analyzer according to claim 111, wherein the low-K dielectric material is chosen from the group consisting of nanopourous silica, hydrogensilsesquioxanes, teflon-AF (Polytetrafluoethylene) and Silicon Oxyflouride.

113. The fluid contamination analyzer according to claim 106, wherein the contaminant selective layer is selected from the group consisting of silicon nitride, silicon dioxide, cerium dioxide, glass, quartz, aluminum oxide, aluminum nitride, boron nitride, titanium nitride, gallium nitride, diamond, diamond like carbon, silicon carbide, parylene, epoxy, polyimide, polycarbonate, polyester, and polyphenylene sulfide.

114. The fluid contamination analyzer according to claim 106, wherein the electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel, copper and silver.

115. The fluid contamination analyzer according to claim 106, wherein the plurality of electrodes are interdigitated.

116. The fluid contamination analyzer according to claim 115, wherein a spacing between adjacent electrodes is between about 1 micron to about 250 microns.

117. The fluid contamination analyzer according to claim 115, wherein a spacing between adjacent electrodes is less than 1 micron.

118. The fluid contamination analyzer according to claim 106, further comprising a temperature sensor for measuring a temperature of the fluid in contact with the sensor.

119. The fluid contamination analyzer according to claim 118, wherein the temperature of the fluid is used to compensate the impedance measurement of the fluid.

120. The fluid contamination analyzer according to claim 118, wherein the temperature sensor is selected from the group consisting of a thermocouple, a thermistor and a resistance temperature detector (RTD).

121. The fluid contamination analyzer according to claim 118, wherein temperature data and/or sensor data is communicated to a remote monitoring device through a communications link.

122. The fluid contamination analyzer according to claim 121, wherein the communications link is a wireless communications link.

123. The fluid contamination analyzer according to claim 106, further comprising a non-volatile memory module for storing data.

124. The fluid contamination analyzer of according to claim 123, wherein the data stored in the non-volatile memory module is at least one of a customer name, a serial number of the sensor, a manufacture date of the sensor, a calibration factor of the sensor, a temperature of the fluid, a sensor type, a location of sensor, a maintenance of the sensor, a selected reference oil, or an impedance of the fluid.

125. The fluid contamination analyzer according to claim 123, wherein the non-volatile memory module is an electrically erasable programmable read only memory module (EEPROM).

126. The fluid contamination analyzer according to claim 106, further comprising a temperature sensor for measuring a temperature of the fluid in contact with the sensor and a non-volatile memory module for storing data.

127. The fluid contamination analyzer according to claim 106, further comprising a plate electrode disposed over the at least one MEMS based sensor, wherein when a fluid is disposed between the plate electrode and the at least one MEMS based sensor an impedance of the fluid is determined using the plate electrode and at least one electrode of the at least one MEMS based sensor or the plurality of electrodes of the MEMS based sensor, thereby providing an indication of fluid contamination.

128. The fluid contamination analyzer according to claim 127, further comprising an electrostatic field control circuit electrically coupled to the plate electrode, wherein the electrostatic field control circuit develops an electrostatic field between the plate electrode and the plurality of electrodes, thereby dislodging with an electrostatic force any particulates that may have become stuck within the sensor due to static charge on the particulates.

129. The fluid contamination analyzer according to claim 127, further comprising:

a plurality of switches, including

a first switch operatively coupled to a first electrode of the plurality of electrodes;

a second switch operatively coupled to a second electrode of the plurality of electrodes;

a third switch operatively coupled to the plate electrode; and

a fourth switch operatively coupled to the first electrode and the second electrode.

130. The fluid contamination analyzer according to claim 129, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance between the plate electrode and at least one electrode of the at least one MEMS based sensor.

131. The fluid contamination analyzer according to claim 129, wherein the plurality of switches selectively configure the fluid contamination analyzer to measure an impedance of the fluid between and adjacent to the electrodes of the MEMS based sensor.

132. The fluid contamination analyzer according to claim 129, wherein the plurality of switches are MEMS switches.

133. The fluid contamination analyzer according to claim 129, wherein the plurality of switches are formed on the substrate of the MEMS based sensor.

134. The fluid contamination analyzer according to claim 128, wherein the plate electrode and the plurality of electrodes are formed from the group consisting of tungsten, platinum, gold, chrome, aluminum, polysilicon, titanium, nickel, copper and silver.

135. The fluid contamination analyzer according to claim 128, wherein the plate electrode is about 1 microns to about 10,000 microns thick.

136. The fluid contamination analyzer according to claim 128, wherein the plate electrode is substantially parallel to a top surface of the at least one MEMS based sensor.

137. The fluid contamination analyzer according to claim 106, wherein the substrate is the contaminant selective layer.

138. The fluid contamination analyzer of claim 105, wherein the substrate is at least one of a glass substrate or a quartz substrate.

139. The fluid contamination analyzer of claim 105, wherein the plurality of electrodes have a width between about 1 micron to about 50 microns.

140. A method of analyzing the quality of a fluid, comprising the steps of:

immersing a sensor into the fluid, wherein the fluid acts as a dielectric for the sensor;

obtaining a complex impedance of the fluid;

measuring a temperature of the fluid in contact with the sensor;

applying a correction factor to the complex impedance based on the measured temperature of the fluid;

estimating the quality of the fluid based on a comparison of known fluids producing substantially the same complex impedance values.

141. The method of claim 140, further comprising the step of obtaining a dissipation factor (DF) of the fluid;

and

further estimating the quality of the fluid based on a comparison of known fluids producing substantially the same DF.

142. The method of claim 140, wherein the step of obtaining the complex impedance of the fluid includes the steps of:

measuring an impedance of the fluid at a first oscillation frequency; and

measuring the impedance of the fluid at a second oscillation frequency.

143. The method of claim 142, wherein the step of measuring an impedance at a first and second oscillation frequency includes the step of using oscillation frequencies between the range of about 0.1 Hz to about 10 MHz.

144. The method of claim 142, wherein the step of measuring an impedance at a first and second oscillation frequency includes the step of using a second oscillation frequency that is about 10 times the first oscillation frequency.

145. The method of claim 142, wherein the step of measuring an impedance at a first and second oscillation frequency includes the step of using a first oscillation frequency between about 100 Hz to about 20 KHz.

146. The method of claim 140, wherein the step of measuring the impedance includes measuring the impedance of the fluid adjacent and above a plurality of electrodes of a MEMS based sensor.

147. The method of claim 146, wherein the step of measuring the impedance of the fluid above the plurality of electrodes includes the step of measuring the impedance of the fluid within a depth that is substantially equal to a separation between adjacent electrodes.

148. The method of claim 140, wherein the step of measuring the impedance includes measuring the impedance of the fluid between a plate electrode and at least one electrode of a MEMS based sensor.

149. The method of claim 140, further comprising the step of applying a contaminant selective layer to the sensor, wherein the contaminant selective layer increases a selectivity of the sensor to at least one type of contaminant.

150. A method of analyzing the quality of a fluid, comprising the steps of:

immersing a sensor into the fluid, wherein the fluid acts as a dielectric for the sensor;

measuring an impedance of the fluid over a temperature gradient; and

estimating the quality of the fluid based on a change in slope of the measured impedance over the temperature gradient.

151. The method of claim 150, wherein the step of measuring the impedance over a temperature gradient includes applying a heat source to the fluid to alter the temperature of the fluid.

152. The method of claim 150 wherein the step of measuring an impedance includes the step of measuring at least one of capacitance, resistance, reactance, dissipation factor, phase angle, admittance, susceptance or conductance.

153. A method of analyzing the quality of a fluid in which a sensor has been immersed, wherein the fluid acts as a dielectric on the sensor, comprising the steps of:

using a contaminant selective layer on the sensor to selectively attract contaminants within the fluid near a surface of the sensor;

measuring an impedance of the fluid near the surface of the sensor; and

correlating the quality of the fluid to the measured impedance of the fluid.

154. The method of claim 153, further comprising the step of using an array of MEMS-based sensors immersed within the fluid, wherein at least one sensor of the array of sensors includes a contaminant selective layer different from a contaminant selective layer of other sensors of the array of sensors.

155. The method of claim 153, wherein the step of measuring an impedance includes the step of measuring at least one of capacitance, resistance, reactance, dissipation factor, phase angle, admittance, susceptance or conductance.

156. A method of analyzing the quality of a sample fluid, wherein the fluid acts as a dielectric on the sensor, comprising the steps of:

immersing a sample sensor in the sample fluid;

immersing a reference sensor in a substantially contaminant-free reference fluid, wherein the reference fluid and the sample fluid are the same type of fluid;

measuring an impedance of the fluid near the surface of the sample sensor and the reference sensor; and

correlating the quality of the sample fluid to the measured impedance of the sample fluid and the reference fluid.

157. The method of claim 156, wherein the step of measuring an impedance includes the step of measuring at least one of capacitance, resistance, reactance, dissipation factor, phase angle, admittance, susceptance or conductance.