Shear sensor array

Patent metadata

Field	Value
Publication number	US-9964476-B2
Application number	US-201414522653-A
Country	US
Kind code	B2
Filing date	Oct 24, 2014
Priority date	Oct 25, 2013
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

The present disclosure relates to shear sensor arrays. In particular, the present disclosure relates to a floating element shear stress sensor array on a chip that is calibrated to high shear levels and is calibrated to determine the sensitivity to streamwise pressure gradients.

First claim

We claim:

1. A micromachined floating element array sensor, comprising:
a) a solid support comprising at least one array of a plurality of floating shear sensors wherein said shear sensors detect shear stress; and b) a controller configured to correct said shear stress for pressure gradient sensitivity by the steps of i) calibrating the pressure gradient sensitivity and shear sensitivity using two or more laminar flow cells with different slot heights at different flow rates; ii) determining the change in capacitance in each configuration; iii) performing a numerical fit of the measured data to the equation

Δ
⁢

⁢
C

=

S
2

⁢

τ

y
⁢

⁢
x

+

S
3

⁢

∂
P

∂
x

 in order to determine the sensitivity to shear, S 2 and the sensitivity to pressure gradient, S 3 , where ΔC is the change in capacitance measured by the sensor, τ yx is the shear stress, and ∂P/∂x is the pressure gradient.

2. The sensor of claim 1 , wherein each of said shear sensors comprise a movable center shuttle, a plurality of sets of variable capacitors, and a series of folded beams.

3. The sensor of claim 1 , wherein a top surface of said shear sensors comprise a plurality of surface bumps configured to increase said sensitivity of said shear sensor to pressure gradients.

4. The sensor of claim 1 , wherein said sensors are in an at least 1 4×4 array.

5. The sensor of claim 1 , wherein said sensors are in at least 2 4×4 arrays.

6. The sensor of claim 1 , wherein said sensors are in at least 4 4×4 arrays.

7. The sensor of claim 1 , wherein said array has a pitch of approximately 2 mm.

8. The sensor of claim 1 , wherein said solid support is approximately 1 cm 2 .

9. The sensor of claim 1 , wherein said array comprises a plurality of electroplated layers of metal.

10. The sensor of claim 9 , wherein said metal is one or more of copper or nickel.

11. The sensor of claim 9 , wherein said array comprises at least 2 layers of electroplating.

12. The sensor of claim 1 , wherein said shear sensors further comprise a capacitance to digital converter.

13. The device of claim 1 , wherein said controller is further configured to calculate shear stress based on said correction of shear stress.

14. A system, comprising:
a) a micromachined floating element array sensor, comprising: a solid support comprising at least one array of a plurality of floating shear sensors wherein said shear sensors detect shear stress and are calibrated to determine the sensitivity of said sensors to pressure gradients; and
b) a controller configured to measure shear stress using said sensor and report said shear stress using said user interface, wherein said controller is further configured to correct said shear stress for pressure gradient sensitivity by the steps of i) calibrating the pressure gradient sensitivity and shear sensitivity using two or more laminar flow cells with different slot heights at different flow rates; ii) determining the change in capacitance in each configuration; iii) performing a numerical fit of the measured data to the equation

Δ
⁢

⁢
C

=

S
2

⁢

τ

y
⁢

⁢
x

+

S
3

⁢

∂
P

∂
x

 in order to determine the sensitivity to shear, S 2 and the sensitivity to pressure gradient, S 3 where ΔC is the change in capacitance measured by the sensor, τ yx is the shear stress, and ∂P/∂x is the pressure gradient.

15. The system of claim 14 , wherein said controller is further configured to calculate shear stress based on said correction of shear stress.

16. A method of detecting shear stress, comprising:
a) contacting a micromachined floating element array sensor, comprising: a solid support comprising at least one array of a plurality of floating shear sensors wherein said shear sensors detect shear stress and are calibrated to determine the sensitivity of said sensors to pressure gradients with a source of shear stress, and
b) measuring said shear stress, wherein said shear stress is corrected for pressure gradient sensitivity by the steps of i) calibrating the pressure gradient sensitivity and shear sensitivity using two or more laminar flow cells with different slot heights at different flow rates; ii) determining the change in capacitance in each configuration; iii) performing a numerical fit of the measured data to the equation

Δ
⁢

⁢
C

=

S
2

⁢

τ

y
⁢

⁢
x

+

S
3

⁢

∂
P

∂
x

 in order to determine the sensitivity to shear, S 2 and the s

Assignees

• Univ Tufts

Inventors

• White Robert D
• Zhao Zhengxin

Classifications

• G01L1/146

  for measuring force distributions, e.g. using force arrays (G01L1/148 takes precedence) · CPC title

• G01L1/14

  by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators · CPC title

• G01N3/24 Primary

  by applying steady shearing forces (G01N3/26, G01N3/28 take precedence) · CPC title

• G01M9/065

  dealing with flow · CPC title

• G01L15/00 Primary

  Devices or apparatus for measuring two or more fluid pressure values simultaneously · CPC title