WEARABLE INDUCTIVE-FORCE SENSOR

• US 20150233776A1
• Filed: 02/20/2015
• Published: 08/20/2015
• Est. Priority Date: 02/20/2014
• Status: Active Grant

• Current Assignee: University of Akron
• Original Assignee: University of Akron
• Inventors: Zhe, Jiang, Du, Li
• Granted Patent: US 10,386,249 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/1038 Measuring plantar pressure during gait
• CPC Class Codes: A61B 5/6807 Footwear
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence

Abstract

A wearable inductive-force sensor, which provides high-sensitivity dynamic measurements of both normal force and shear force, utilizes three spiral planar force sensing coils. These spiral planar coils allow the measurement of shear force in the x and y directions and the measurement of a normal force in the z direction. The force sensor is configured to be mounted in various locations, such as an insole of a shoe, so as to provide real-time force sensing of forces that are applied to a patient'"'"'s feet as they move. In addition, force-measurement electronics used with the force sensor are configured to use resonance-frequency division signal multiplexing to monitor the response of the force sensing coils, which allows the sensor to have minimal complexity, while still being highly sensitive.

Claims

1. A force sensor comprising:

a substrate;

a first, second and third coil disposed on said substrate, said coils electrically coupled in series;

a capacitor coupled in parallel with each one of said plurality of coils;

a flexible section disposed on said plurality of coils; and

a rigid section disposed on said flexible section, said rigid section being formed of conductive material, such that said flexible section allows said rigid section to move relative to said coils;

wherein said flexible section has at least two edges, such that one edge passes through the center of said first coil and another edge passes through the center of said second coil, and said third coil is disposed between said flexible section and said substrate, such that said coils detect a change in impedance based on the movement of said rigid section relative to said coils.

2. The force sensor of claim 1, wherein said substrate comprises an insole of a shoe.

3. The force sensor of claim 1, wherein said substrate comprises a dielectric material.

4. The force sensor of claim 1, wherein said coils comprise spiral-wound coils.

5. The force sensor of claim 4, wherein said spiral-wound coils comprise planar coils.

6. The force sensor of claim 5, wherein said spiral-wound planar coils comprise a plurality of turns.

7. The force sensor of claim 1, wherein said flexible section is formed of rubber.

8. The force sensor of claim 1, wherein said rigid section comprises stainless steel.

9. The force sensor of claim 1, further comprising:

a force-measurement device coupled to said first, second and third coils, wherein said force-measurement device is configured to measure the amount of movement of said rigid plate relative to said substrate, so as to calculate therefrom an amount of force applied to the sensor.

10. The force sensor of claim 9, wherein said force-measurement device comprises:

a resistor coupled in series with said first, second and third coils;

an A.C. (alternating current) signal generator that is coupled in series with said resistor; and

a data acquisition unit coupled in parallel with said first, second and third coils;

wherein said A.C. signal generator generates a combined signal, which includes a plurality of signals each having a resonant frequency associated with said first, second and third coils respectively, such that said data acquisition unit monitors the response of said first, second and third coils to identify the amount of force applied to the sensor.

11. The force sensor of claim 9, wherein said force-measurement device includes a communication interface to transfer the calculated amount of force to a remote computer.

12. The force sensor of claim 9, wherein said force-measurement device calculates the amount of force in real-time.