# US 8,751,172 B2 · Microelectromechanical viscosity measurement devices and methods thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,751,172 B2 - Document ID: US8751172B2 - Status: Granted - Kind: B2 - Application number: 12/826,156 - Filed: 2010-06-29 - Published: 2010-12-30 - Granted: 2014-06-10 - Earliest claimed: 2009-06-29 - Assignees: Rochester Institute of Technology - Applicants: Ivan Puchades; Lynn Fuller - Inventors: Ivan Puchades; Lynn Fuller - Web page: https://patentgrep.com/patent/US8751172B2 ## CPC - G01N 11/16: by measuring damping effect upon oscillatory body - G01N 9/002: {using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence)} - G01N 2011/0066: {electrical properties} - G01N 2011/0093: {thermal properties} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A viscosity measurement device includes a flexible membrane, an actuation heating element, and a displacement sensor apparatus. The actuation heating element is on and spaced in from an outer periphery of the flexible membrane. The displacement sensor apparatus is coupled to the flexible membrane and measures and outputs a displacement signal representative of a viscosity of a fluid in contact with the flexible membrane. ## Claims ### Claim 1 A viscometer system comprising: a viscosity measurement device comprising: a flexible membrane; a supporting structure which supports and fixes an entire outer periphery of a moveable portion of the flexible membrane; an actuation heating element on and spaced in from the outer periphery of the flexible membrane which provides the heat to create thermal expansion differences between the membrane and a metal plate which is in at least partial alignment with the actuation heating element; and at least one displacement sensor coupled to the flexible membrane that measures the displacement of the membrane with the metal plate and outputs a displacement signal representative of a viscosity of a fluid in contact with the flexible membrane. ### Claim 2 (depends on 1) The system as set forth in claim 1 further comprising a driving device configured to apply a driving signal at a first frequency and substantially constant power to the actuation heating element. ### Claim 3 (depends on 2) The system as set forth in claim 2 further comprising a viscosity computing device configured to determine and provide a viscosity of the fluid in contact with the flexible membrane based on the displacement signal. ### Claim 4 (depends on 3) The system as set forth in claim 3 wherein the viscosity computing device is further configured to determine from the displacement signal a resonant frequency or a quality factor in the fluid and determines and provides at least one of density or the viscosity of the fluid based on the determined resonance frequency and the quality factor. ### Claim 5 (depends on 4) The system as set forth in claim 4 wherein the viscosity computing device is further configured to determine a first duration for a pulse of the driving signal which is uninfluenced by the heat dissipation characteristics of the fluid and controls the driving device to apply the driving signal with the determined pulse. ### Claim 6 (depends on 1) The system as set forth in claim 1 wherein the at least one displacement sensor comprises a plurality of piezoresistive sensing elements on the flexible membrane. ### Claim 7 (depends on 6) The system as set forth in claim 6 wherein the plurality of piezoresistive sensing elements further comprise a piezoresistive Wheatstone bridge. ### Claim 8 (depends on 6) The system as set forth in claim 6 wherein the flexible membrane further comprises a silicon substrate, the actuation heating element further comprises a doped region in the silicon substrate, and the plurality of piezoresistive sensing elements further comprise doped polysilicon. ### Claim 9 (depends on 1) The system as set forth in claim 1 further comprising a thermal isolation layer formed over the actuation heating element and the flexible membrane. ### Claim 10 (depends on 1) The system as set forth in claim 1 further comprising a thermal isolation layer disposed between the actuation heating element and the metal plate. ### Claim 11 A method of making a viscosity measurement device, the method comprising: providing an actuation heating element on and spaced in from an outer periphery of a flexible membrane which provides the heat to create thermal expansion differences between the membrane and a metal plate which is in at least partial alignment with the actuation heating element, the entire outer periphery of a moveable portion of the flexible membrane supported and fixed by a supporting structure; coupling at least one displacement sensor to the flexible membrane that measures the displacement of the membrane with the metal plate and outputs a displacement signal representative of a viscosity of a fluid in contact with the flexible membrane. ### Claim 12 (depends on 11) The method as set forth in claim 11 further comprising a providing a driving device configured to apply a driving signal at a first frequency and substantially constant power to the actuation heating element. ### Claim 13 (depends on 12) The method as set forth in claim 12 further comprising providing a viscosity computing device configured to determine and output a viscosity of the fluid in contact with the flexible membrane based on the displacement signal. ### Claim 14 (depends on 13) The method as set forth in claim 13 wherein the providing a viscosity computing device further comprises providing a viscosity computing device further configured to determine from the displacement signal a resonant frequency and a quality factor in the fluid and determine and provide at least one of density or the viscosity of the fluid based on the determined resonance frequency and the quality factor. ### Claim 15 (depends on 14) The method as set forth in claim 14 wherein the providing a viscosity computing device further comprises providing a viscosity computing device further configured to determine a first duration for a pulse of the driving signal which is uninfluenced by the heat dissipation characteristics of the fluid and controls the driving device to apply the driving signal with the determined pulse. ### Claim 16 (depends on 11) The method as set forth in claim 11 wherein the coupling at least one displacement sensor comprises forming a plurality of piezoresistive sensing elements on the flexible membrane. ### Claim 17 (depends on 16) The method as set forth in claim 16 wherein the forming the plurality of piezoresistive sensing elements further comprise forming a piezoresistive Wheatstone bridge on the flexible membrane. ### Claim 18 (depends on 16) The method as set forth in claim 16 wherein the flexible membrane further comprises a silicon substrate, the actuation heating element further comprises a doped region in the silicon substrate, and the plurality of piezoresistive sensing elements further comprise doped polysilicon. ### Claim 19 (depends on 11) The method as set forth in claim 11 further comprising providing a thermal isolation layer formed over the actuation heating element and the flexible membrane. ### Claim 20 (depends on 11) The method as set forth in claim 11 further comprising providing a thermal isolation layer disposed between the actuation heating element and the metal plate. ### Claim 21 A viscometer system comprising: a flexible membrane; an actuation heating element on and spaced in from an outer periphery of the flexible membrane which provides the heat to create thermal expansion differences between the membrane and a metal plate which is in at least partial alignment with the actuation heating element; a driving device configured to apply a driving signal at a first frequency and substantially constant power to the actuation heating element; at least one displacement sensor coupled to the flexible membrane that measures the displacement of the membrane with the metal plate and outputs a displacement signal representative of a viscosity of a fluid in contact with the flexible membrane; and a viscosity computing device configured to determine and provide a viscosity of the fluid in contact with the flexible membrane based on the displacement signal, to determine from the displacement signal a resonant frequency and a quality factor in the fluid and determines and provides at least one of density or the viscosity of the fluid based on the determined resonance frequency and the quality factor, and to determine a first duration for a pulse of the driving signal which is uninfluenced by the heat dissipation characteristics of the fluid and controls the driving device to apply the driving signal with the determined pulse. ### Claim 22 (depends on 21) The system as set forth in claim 21 further comprising a thermal isolation layer formed over the actuation heating element and the flexible membrane. ### Claim 23 (depends on 21) The system as set forth in claim 21 further comprising a thermal isolation layer disposed between the actuation heating element and the metal plate. ### Claim 24 A method of making a viscosity measurement device, the method comprising: providing an actuation heating element on and spaced in from an outer periphery of a flexible membrane; providing at least one metal plate on the flexible membrane and at least in partial alignment with the actuation heating element; providing a driving device configured to apply a driving signal at a first frequency and substantially constant power to the actuation heating element; coupling at least one displacement sensor to the flexible membrane that measures the displacement of the membrane with the metal plate and outputs a displacement signal representative of a viscosity of a fluid in contact with the flexible membrane; providing a viscosity computing device configured to determine and output a viscosity of the fluid in contact with the flexible membrane based on the displacement signal, to determine from the displacement signal a resonant frequency and a quality factor in the fluid and determine and provide at least one of density or the viscosity of the fluid based on the determined resonance frequency and the quality factor, and to determine a first duration for a pulse of the driving signal which is uninfluenced by the heat dissipation characteristics of the fluid and controls the driving device to apply the driving signal with the determined pulse. ### Claim 25 (depends on 24) The method as set forth in claim 24 further comprising providing a thermal isolation layer formed over the actuation heating element and the flexible membrane. ### Claim 26 (depends on 24) The method as set forth in claim 24 further comprising providing a thermal isolation layer disposed between the actuation heating element and the metal plate. ### Claim 27 A viscometer system comprising: a flexible membrane; a supporting structure which supports and fixes an entire outer periphery of the flexible membrane; an actuation heating element on and spaced in from an outer periphery of the flexible membrane which provides the heat to create thermal expansion differences between the membrane and a metal plate which is in at least partial alignment with the actuation heating element; a driving device configured to apply a driving signal at a first frequency and substantially constant power to the actuation heating element; at least one displacement sensor coupled to the flexible membrane that measures the displacement of the membrane with the metal plate and outputs a displacement signal representative of a viscosity of a fluid in contact with the flexible membrane; and a viscosity computing device configured to determine and provide a viscosity of the fluid in contact with the flexible membrane based on the displacement signal, wherein the viscosity computing device is further configured to determine from the displacement signal a resonant frequency or a quality factor in the fluid and determines and provides at least one of density or the viscosity of the fluid based on the determined resonance frequency and the quality factor, and wherein the viscosity computing device is further configured to determine a first duration for a pulse of the driving signal which is uninfluenced by the heat dissipation characteristics of the fluid and controls the driving device to apply the driving signal with the determined pulse. ### Claim 28 (depends on 27) The system as set forth in claim 27 further comprising a thermal isolation layer formed over the actuation heating element and the flexible membrane. ### Claim 29 (depends on 27) The system as set forth in claim 27 further comprising a thermal isolation layer disposed between the actuation heating element and the one metal plate. ### Claim 30 A method of making a viscosity measurement device, the method comprising: providing an actuation heating element on and spaced in from an outer periphery of a flexible membrane, an entire outer periphery of the flexible membrane supported and fixed by a supporting structure; providing at least one metal plate on the flexible membrane and at least in partial alignment with the actuation heating element; providing a driving device configured to apply a driving signal at a first frequency and substantially constant power to the actuation heating element; coupling at least one displacement sensor to the flexible membrane that measures the displacement of the membrane with the metal plate and outputs a displacement signal representative of a viscosity of a fluid in contact with the flexible membrane; and providing a viscosity computing device configured to determine and output a viscosity of the fluid in contact with the flexible membrane based on the displacement signal, wherein the providing a viscosity computing device further comprises providing a viscosity computing device further configured to determine from the displacement signal a resonant frequency and a quality factor in the fluid and determine and provide at least one of density or the viscosity of the fluid based on the determined resonance frequency and the quality factor, and wherein the providing a viscosity computing device further comprises providing a viscosity computing device further configured to determine a first duration for a pulse of the driving signal which is uninfluenced by the heat dissipation characteristics of the fluid and controls the driving device to apply the driving signal with the determined pulse. ### Claim 31 (depends on 30) The method as set forth in claim 30 further comprising providing a thermal isolation layer formed over the actuation heating element and the flexible membrane. ### Claim 32 (depends on 30) The method as set forth in claim 30 further comprising providing a thermal isolation layer disposed between the actuation heating element and the metal plate.