Strain monitoring system and apparatus

• US 9,060,743 B2
• Filed: 01/03/2014
• Issued: 06/23/2015
• Est. Priority Date: 07/08/2004
• Status: Active Grant

• Current Assignee: Deborah Susan Munro
• Original Assignee: Deborah Munro
• Inventors: Munro, Deborah, Lee, Eunice, Ramahi, Amjad
• Primary Examiner(s): EISEMAN, ADAM JARED
• Application Number:
  US14/147,299
• Publication Number:
  US 20140163423A1
• Time in Patent Office: 536 Days
• Field of Search: 600/587, 600593-595, 738/62, 736/26, 738/626.8, 738/626.9
• US Class Current: 1/1
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2562/0261 Strain gauges
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/103 Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: A61B 5/1126 using a particular sensing technique
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/4566 Evaluating the spine A61B5/4561 takes precedence
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 90/06 Measuring instruments not otherwise provided for
• CPC Class Codes: A61B 90/98 using electromagnetic means, e.g. transponders
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2002/30668 : Means for transferring electromagnetic energy to implants
• CPC Class Codes: A61F 2250/0001 : Means for transferring electromagnetic energy to implants

Abstract

A system for monitoring strain as an indicator of biological conditions, such as spinal fusion, glucose levels, spinal loading, and heart rate. The system includes an inter-digitated capacitor sensor, and RF transmitter, and an associated antenna, all of which are microminiature or microscopic in size and can be implanted in a biological host such as a human or animal. An inductively coupled power supply is also employed to avoid the need for implantation of chemical batteries. Power is provided to the sensor and transmitter, and data is transmitted from the sensor, when an external receiving device, such as a handheld RF ID type receiver, is placed proximate the location of the implanted sensor, transmitter and inductively coupled power supply. The implanted sensor, transmitter and inductively coupled power supply can be left in place permanently or removed when desired.

Claims

1. A method of detecting strain with a strain sensor apparatus, the method comprising:

arranging an area variation motion sensor for biological implantation;

forming an area variation capacitor with at least two plates;

providing a capacitance from said capacitor;

coupling said plates to a surface;

configuring said plates to allow movement with bending of said surface;

creating a change in area between said plates with said movement;

creating a change of capacitance with said movement;

and

detecting strain as a result of said change of capacitance.

2. The method of claim 1, further comprising:

coupling a transmitter to the area variation capacitor;

coupling an antenna to said transmitter;

adapting said area variation capacitor for biological implantation;

encapsulating said area variation capacitor in a sealed housing; and

sensing strain with said area variation capacitor.

3. The method of claim 2, further comprising:

forming said sealed housing from said transmitter and said antenna; and

encapsulating said sensor with said housing.

4. The method of claim 1, whereby the change in capacitance is created by the area of overlap of said plates.

5. The method of claim 4, whereby the change in capacitance is directly related to motion of said plates.

6. The method of claim 4, whereby the change in capacitance is on the scale of 10⁻

16 F.

7. A method of detecting strain with a strain sensor apparatus, the method comprising:

arranging an area variation motion sensor for biological implantation;

forming an area variation capacitor with at least two plates, each having a plurality of free-standing, inter-digitated fingers arranged to form the area variation inter-digitated capacitor;

providing a capacitance from said capacitor;

coupling said plates to a surface;

configuring said plates to allow movement with bending of said surface;

creating a change in area between said inter-digitated fingers due to lateral movement of the inter-digitated fingers with said movement;

creating a change of capacitance with said movement; and

detecting strain as a result of said change of capacitance.

8. The method of claim 7, further comprising:

coupling a transmitter to the area variation capacitor;

coupling an antenna to said transmitter;

adapting said area variation capacitor for biological implantation;

encapsulating said area variation capacitor in a sealed housing; and

sensing strain with said area variation capacitor.

9. The method of claim 8, further comprising:

forming said sealed housing from said transmitter and said antenna; and

encapsulating said sensor with said housing.

10. The method of claim 7, whereby the change in capacitance is created by the area of overlap of said plates.

11. The method of claim 10, whereby the change in capacitance is directly related to motion of said plates.

12. The method of claim 10, whereby the change in capacitance is on the scale of 10⁻

16 F.