OMNIDIRECTIONAL ACCELEROMETER DEVICE AND MEDICAL DEVICE INCORPORATING SAME

• US 20110105955A1
• Filed: 11/03/2009
• Published: 05/05/2011
• Est. Priority Date: 11/03/2009
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: YUDOVSKY, Dmitry, HANSON, Ian B., MOBERG, Sheldon B.
• Granted Patent: US 8,386,042 B2
• Time in Patent Office: Days
• US Class Current: 600/595
• CPC Class Codes: A61M 2205/0294 Piezoelectric materials
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2230/63 Motion, e.g. physical activity
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/09 by piezoelectric pick-up
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass

Abstract

A portable medical device is provided with an internal accelerometer device. The medical device includes a circuit board, the accelerometer device, and a response module coupled to the accelerometer device. The accelerometer device is mechanically and electrically coupled to the circuit board, and it includes a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, piezoelectric material for the mass-supporting arm, and a proof mass supported by the mass-supporting arms. Each of the mass-supporting arms has one of the sensor electrodes located thereon. Acceleration of the proof mass causes deflection of the piezoelectric material, which generates respective sensor signals at one or more of the sensor electrodes. The response module is configured to initiate an acceleration-dependent operation of the portable medical device in response to generated sensor signals present at the sensor electrodes.

Claims

1. An omnidirectional accelerometer device comprising:

a piezoelectric sensor element comprising an electrically conductive support substrate, a layer of piezoelectric material overlying the support substrate, and a plurality of electrically conductive sensor electrodes overlying the piezoelectric material, the piezoelectric sensor element further comprising a mass-supporting platform and a plurality of mass-supporting arms, each of the sensor electrodes being located on a corresponding one of the mass-supporting arms; and

a proof mass coupled to the mass-supporting platform.

2. The omnidirectional accelerometer device of claim 1, wherein each of the sensor electrodes represents a separate and distinct electrical sensing node.

3. The omnidirectional accelerometer device of claim 1, further comprising an electromechanical mounting arrangement configured to mechanically and electrically couple the piezoelectric sensor element to a circuit board.

4. The omnidirectional accelerometer device of claim 3, the electromechanical mounting arrangement comprising:

a plurality of electrically conductive mounting bases; and

a plurality of electrically conductive mounting tabs, wherein each of the mass-supporting arms is mechanically and electrically coupled to the circuit board with one of the mounting bases and one of the mounting tabs, the mounting bases are electrically coupled to the support substrate, and each of the mounting tabs is electrically coupled to a respective one of the sensor electrodes.

5. The omnidirectional accelerometer device of claim 1, further comprising a signal processing module coupled to the sensor electrodes, the signal processing module being configured to process sensor signals generated in response to deflection of the piezoelectric sensor element caused by the proof mass.

6. The omnidirectional accelerometer device of claim 5, the signal processing module comprising:

a first signal processing sub-module configured to process the sensor signals for human activity monitoring; and

a second signal processing sub-module configured to process the sensor signals for impact detection.

7. The omnidirectional accelerometer device of claim 6, wherein the first signal processing sub-module and the second signal processing sub-module are coupled in parallel to the sensor electrodes to enable concurrent processing of the sensor signals.

8. The omnidirectional accelerometer device of claim 1, wherein the proof mass is centrally located relative to the mass-supporting arms, and the mass-supporting arms are symmetrically positioned relative to the proof mass.

9. A portable medical device comprising:

a circuit board;

an accelerometer device mechanically and electrically coupled to the circuit board, the accelerometer device comprising;

a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, each of the mass-supporting arms having one of the sensor electrodes located thereon;

piezoelectric material for the mass-supporting arms; and

a proof mass supported by the mass-supporting arms, wherein acceleration of the proof mass causes deflection of the piezoelectric material, which generates respective sensor signals at one or more of the sensor electrodes; and

a response module coupled to the accelerometer device, the response module being configured to initiate an acceleration-dependent operation of the portable medical device in response to generated sensor signals present at the sensor electrodes.

10. The portable medical device of claim 9, further comprising a signal processing module coupled to the sensor electrodes and to the response module, the signal processing module being configured to process the generated sensor signals and provide associated control signals to the response module.

11. The portable medical device of claim 10, the signal processing module comprising:

a first signal processing sub-module configured to process the generated sensor signals for human activity monitoring; and

a second signal processing sub-module configured to process the generated sensor signals for impact detection.

12. The portable medical device of claim 11, wherein the response module initiates an alert operation when the second signal processing sub-module determines that the accelerometer device has been subjected to an impact that exceeds an impact threshold.

13. The portable medical device of claim 11, wherein:

the first signal processing sub-module is configured to generate an estimated human activity metric based upon the generated sensor signals; and

the response module initiates a function that is influenced by the estimated human activity metric.

14. The portable medical device of claim 9, wherein the proof mass is centrally located relative to the mass-supporting arms, and the mass-supporting arms are symmetrically positioned about the proof mass.

15. An omnidirectional accelerometer device comprising:

a piezoelectric sensor element comprising a mass-supporting platform and a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, each of the mass-supporting arms extending from the mass-supporting platform, and each of the mass-supporting arms having one of the sensor electrodes formed thereon;

a connecting rod having a mounting end, a mass end, and a longitudinal length defined between the mounting end and the mass end, the mounting end being coupled to the mass-supporting platform; and

a proof mass coupled to the mass end of the connecting rod, wherein acceleration of the proof mass causes deflection of the mass-supporting arms, which generates distinct sensor signals at the sensor electrodes;

wherein;

the longitudinal length of the connecting rod is tuned in accordance with a predetermined parallel acceleration sensitivity for the omnidirectional accelerometer device;

each of the sensor electrodes has a longitudinal sensor length along its respective mass-supporting arm; and

the longitudinal sensor length is tuned in accordance with a predetermined perpendicular acceleration sensitivity for the omnidirectional accelerometer device.

16. The omnidirectional accelerometer device of claim 15, wherein the piezoelectric sensor element comprises:

an electrically conductive support substrate;

a layer of piezoelectric material overlying the support substrate; and

the sensor electrodes overlying the piezoelectric material, the sensor electrodes being formed from an electrically conductive material.

17. The omnidirectional accelerometer device of claim 16, wherein:

the electrically conductive support substrate corresponds to a reference voltage; and

each of the sensor electrodes corresponds to a respective sensor signal voltage.

18. The omnidirectional accelerometer device of claim 15, wherein:

the mounting end of the connecting rod is coupled to a center location of the mass-supporting platform; and

the mass-supporting arms are symmetrically positioned relative to the center location.

19. The omnidirectional accelerometer device of claim 15, wherein adjacent mass-supporting arms are orthogonal.

20. The omnidirectional accelerometer device of claim 15, wherein adjacent mass-supporting arms define a separation angle for the piezoelectric sensor element.