Rheometer for rapidly measuring small quantity samples

• US 20050166667A1
• Filed: 03/25/2005
• Published: 08/04/2005
• Est. Priority Date: 08/03/2000
• Status: Active Grant

• Current Assignee: Meas France
• Original Assignee: Symyx Technologies Incorporated (Dassault Systemes SA)
• Inventors: Carlson, Eric, Srinivasan, Ravi, Hajduk, Damian
• Granted Patent: US 7,047,794 B2
• Time in Patent Office: Days
• US Class Current: 73/54.370
• CPC Class Codes: G01N 11/16 by measuring damping effect upon oscillatory body
• CPC Class Codes: G01N 2203/0051 Piezoelectric means
• CPC Class Codes: G01N 2203/0286 Miniature specimen; Testing on microregions of a specimen
• CPC Class Codes: G01N 2203/0623 using piezoelectric gauges
• CPC Class Codes: G01N 3/24 by applying steady shearing forces G01N3/26, G01N3/28 take precedence

Abstract

The present invention relates to a miniature rheometer, a parallel rheometer, and improved force sensor elements which may advantageously be used in combination with the miniature rheometer and the parallel rheometer. The miniature rheometer is adapted to determine rheological characteristics of materials which are provided in the form of small quantity samples. The miniature rheometer comprises an actuating element, a sensing element and a feedback circuit to provide rebalance of the shear force applied by the sample to the sensing element, which insures an exceptional stiffness in determining the shear strain so as to allow measurements of high accuracy. The parallel rheometer of the present invention allows simultaneous measurements of a plurality of samples so as to allow of a plurality of samples within a short time period. The force sensor element according to the present invention allows simultaneous measurement of a shear force and a normal force applied to the sensor element. Moreover, a rheometer is provided which comprises a force sensor based on stress-optic material.

Claims

1-77. -77. (canceled)

78. A method for measuring a fluid property, the method comprising

providing a sensor that includes:

a substrate having a recess formed therein,

a plate disposed within the recess,

a plurality of tethers suspendedly attaching the plate to the substrate for enabling reciprocating motion of the plate relative to the substrate, and

at least one contact pad on the substrate adapted for electrical signaling communication with a power source and processing electronics,

contacting the plate with a test fluid,

oscillating the plate relative to the substrate, and

determining at least one characteristic of the test fluid in response to contact with the plate.

79. The method of claim 78 wherein the sensor further comprises at least one electrode on the plate.

80. The method of claim 79 wherein the oscillating step comprises applying an electric field to the plate.

81. The method of claim 79 wherein the oscillating step comprises oscillating the plate within a magnetic field.

82. The method of claim 79 wherein the detecting step comprises detecting changes in rheological characteristic of the test fluid.

83. The method of claim 79 wherein the detecting step comprises detecting changes in shear or normal forces

84. A fluid sensor comprising:

a fluid sensing element, the fluid sensing element comprising

a substrate having a recess formed therein,

a plate disposed within the recess, and

a plurality of tethers suspendedly attaching the plate to the substrate for enabling oscillation of the plate relative to the substrate,

at least one contact pad on the substrate, adapted for electrical signaling communication with a power source and processing electronics; and

at least one electrode on the plate.

85. The sensor of claim 84 wherein the substrate, plate and tethers are micromachined.

86. The sensor of claim 84 wherein the substrate, plate and tethers comprise silicon.

87. The sensor of claim 84 further comprising at least one strain gauge located on one of the tethers, wherein the at least one strain gauge is connected to the at least one contact pad.

88. The sensor of claim 84 further comprising at least one strain gauge located on each of the tethers, wherein the strain gauges are connected to the at least one contact pad.