Shielded capacitor sensor system for medical applications and method

• US 9,358,136 B2
• Filed: 03/24/2014
• Issued: 06/07/2016
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: OrthoSensor, Inc (Stryker Corporation)
• Inventors: Stein, Marc, Chase, Andrew
• Primary Examiner(s): Thompson, Jewel V
• Application Number:
  US14/223,943
• Publication Number:
  US 20140200584A1
• Time in Patent Office: 806 Days
• Field of Search: 733/790.1, 606/87, 606/130, 606/102, 600/587
• US Class Current: 1/1
• CPC Class Codes: A61B 17/1615 Drill bits, i.e. rotating tools extending from a handpiece to contact the worked material
• CPC Class Codes: A61B 17/1666 for the acetabulum
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 2562/0252 Load cells
• CPC Class Codes: A61B 2562/182 Electrical shielding, e.g. using a Faraday cage
• 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 5/4509 Bone density determination
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take 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 5/6847 mounted on an invasive device
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06

Abstract

A measurement system for measuring a parameter of the muscular-skeletal system is disclosed. The measurement system comprises a capacitor, a signal generator, a digital counter, counter register, a digital clock, a digital timer, and a data register. The sensor of the measurement system is the capacitor. The measurement system generates a repeating signal having a measurement cycle that corresponds to the capacitance of the capacitor. The capacitor comprises more than one capacitor mechanically in series. Electrically, the capacitor comprises more than one capacitor in parallel. In one embodiment, the capacitor includes a dielectric layer comprising polyimide. A force, pressure, or load is applied to the capacitor that elastically compresses the device. The capacitor is shielded from parasitic coupling and parasitic capacitance.

Claims

1. An orthopedic surgical system comprising:

a bone-cutting tool comprising;

a sensor configured to measure position and trajectory of the bone-cutting tool;

electronic circuitry coupled to the sensor where the electronic circuitry includes a transmitter and where the transmitter is configured to transmit data from the sensor; and

a housing where the electronic circuitry is within the housing of the bone-cutting tool.

2. The system of claim 1 further including a remote system having a processor where the remote system receives and processes data from the bone-cutting tool and where the remote system is configured to display position and trajectory data of the bone-cutting tool in real-time.

3. The system of claim 2 where the remote system is configured to use the position and trajectory data collected from the bone-cutting tool to direct a position and trajectory of another tool.

4. The system of claim 1 where the sensor is a 3-axis accelerometer.

5. The system of claim 1 further including a force sensor coupled to the electronic circuitry where the force sensor is configured to measure a force applied by the bone-cutting tool.

6. The system of claim 5 where the force sensor conforms to a non-planar surface.

7. The system of claim 5 where the force sensor is an elastically compressible capacitor.

8. The system of claim 5 where the bone-cutting tool is a reamer.

9. The system of claim 5 where the force sensor is coupled to a compliant surface configured to transfer a force to the force sensor.

10. The system of claim 5 further including a plurality of force sensors coupled to the electronic circuitry where the plurality of force sensors are configured to measure a force magnitude and a position of applied force by the bone cutting tool.

11. An orthopedic surgical system comprising:

a bone-cutting tool comprising;

a three-axis accelerometer configured to measure position and trajectory of the bone cutting tool;

electronic circuitry coupled to the sensor where the electronic circuitry includes a transmitter and where the transmitter is configured to transmit data from the three-axis accelerometer;

a housing where the electronic circuitry is within the housing of the bone-cutting tool; and

a remote system having a processor where the remote system is configured to receive and process data from the bone-cutting tool and where the remote system is configured to display position and trajectory data from the bone cutting tool in real-time.

12. The system of claim 11 where the remote system is configured to use the position and trajectory data from the bone cutting tool to direct a position and trajectory of another tool.

13. The system of claim 12 further including a plurality of force sensors coupled to the electronic circuitry where the plurality of force sensors are configured to measure a force magnitude and position of force.

14. The system of claim 13 where the plurality of force sensors conform to a non-planar surface.

15. The system of claim 13 where the plurality of force sensors are elastically compressible capacitors.

16. The system of claim 13 where the bone-cutting tool has a non-planar cutting head.

17. The system of claim 13 where the plurality of force sensors are coupled to a compliant surface configured to transfer a force to the plurality of force sensors.

18. An orthopedic surgical system comprising:

a bone-cutting tool comprising;

a three-axis accelerometer configured to measure position and trajectory of the bone cutting tool;

electronic circuitry coupled to the sensor where the electronic circuitry includes a transmitter and where the transmitter is configured to transmit data from the three-axis accelerometer;

a housing where the electronic circuitry is within the housing of the bone-cutting tool; and

a cutting head;

a force sensor coupled to the electronic circuitry where the force sensor couples to the cutting head and where the force sensor is configured to measure a force applied to the cutting head.

19. The system of claim 18 further including a remote system having a processor where the remote system is configured to receive and process data from the bone-cutting tool and where the remote system is configured to display position and trajectory data from the bone cutting tool in real-time and where the remote system is configured to display a force applied by the cutting head to a bone.

20. The system of claim 18 where the force sensor is an elastically compressible capacitor.