IMPEDANCE MEASUREMENT DEVICES, SYSTEMS, AND METHODS

• US 20150359452A1
• Filed: 07/22/2014
• Published: 12/17/2015
• Est. Priority Date: 06/12/2014
• Status: Active Grant

• Current Assignee: Physiowave, Inc. (Omron Corporation)
• Original Assignee: Physiowave, Inc. (Omron Corporation)
• Inventors: Giovangrandi, Laurent B., Kovacs, Gregory T., Darling, Robert Bruce
• Granted Patent: US 9,549,680 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02444 Details of sensor A61B5/02427 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/1102 Ballistocardiography
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/4023 Evaluating sense of balance
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: G01G 19/50 having additional measuring devices, e.g. for height

Abstract

Aspects of the present disclosure are directed toward obtaining a plurality of impedance-measurement signals while a set of at least three electrodes are concurrently contacting a user. Additionally, various aspects of the present disclosure include determining a plurality of pulse characteristic signals based on the plurality of impedance-measurement signals. One of the pulse characteristic signals is extracted from one of the impedance-measurement signals and is used as a timing reference to extract and process another of the pulse characteristic signals.

Claims

1. A method comprising:

for a plurality of interleaved electrodes in contact with a user'"'"'s foot, sensing electrical signals between different ones of the electrodes;

selecting a set of the electrodes based on the sensed electrical signals, the set including two selected electrodes for obtaining impedance measurements from the user'"'"'s foot; and

using the two selected electrodes and while the two selected electrodes and at least one additional electrode are concurrently contacting the user, obtaining impedance measurements that characterize a physiological aspect of the user'"'"'s body, the additional electrode being in contact with a location of the user that does not include the foot.

2. The method of claim 1, wherein selecting the set of electrodes includes determining a foot placement characteristic of the foot relative to the electrodes and selecting the two selected electrodes based on the foot placement characteristic.

3. The method of claim 1, wherein sensing the electrical signals includes injecting current into the foot and sensing signals that are responsive to the injected current, and selecting the set of electrodes includes identifying a location of the foot relative to the electrodes based on the injected current.

4. The method of claim 1, wherein sensing electrical signals between different ones of the electrodes includes sensing capacitance.

5. The method of claim 1, wherein selecting the set of the electrodes includes selecting the two selected electrodes as two electrodes that provide a high signal-to-noise ratio (SNR), relative to a SNR of the respective electrical signals sensed from other pairs of the electrodes.

6. The method of claim 1, wherein sensing the electrical signals includes sensing the electrical signals using at least two Kelvin electrode pairs.

7. The method of claim 1, wherein selecting the set of electrodes includes selecting the two selected electrodes by comparing the respective electrical signals as part of a signal optimization process and selecting the two selected electrodes based on the comparing.

8. The method of claim 1, further including determining a physiological characteristic of the user by extracting a first signal from the impedance measurements, and extracting a second signal from the impedance measurements using the first signal as a timing reference.

9. The method of claim 1, wherein obtaining the impedance measurements includes obtaining a plurality of impedance measurement signals via the two selected electrodes, further including:

determining a plurality of pulse characteristic signals based on the impedance measurements,

extracting one of the pulse characteristic signals from one of the impedance measurements, and

using the extracted pulse characteristic signals as a timing reference to extract and process another of the pulse characteristic signals.

10. An apparatus comprising:

a plurality of interleaved electrodes configured and arranged to contact a user'"'"'s foot;

a first circuit configured and arranged to sense electrical signals between different ones of the electrodes, and to select a set of the electrodes based on the sensed electrical signals, the set including two selected electrodes for obtaining impedance measurements from the user'"'"'s foot; and

a second circuit configured and arranged to obtain impedance measurements that characterize a physiological aspect of the user'"'"'s body, using the two selected electrodes while the two selected electrodes and at least one additional electrode are concurrently contacting the user, the additional electrode being in contact with a location of the user that does not include the foot.

11. The apparatus of claim 10, wherein the first circuit is configured and arranged to determine a foot placement characteristic of the foot relative to the electrodes, and to select the two selected electrodes based on the foot placement characteristic.

12. The apparatus of claim 10, wherein the first circuit is configured and arranged to inject current into the foot, sense signals that are responsive to the injected current, and select the set of electrodes by identifying a location of the foot relative to the electrodes based on the injected current.

13. The apparatus of claim 10, wherein the first circuit is configured and arranged to select the two selected electrodes by selecting the two electrodes that provide a high signal-to-noise ratio (SNR), relative to a SNR of the respective electrical signals sensed from other pairs of the electrodes.

14. The apparatus of claim 10, wherein the second circuit is configured and arranged to determine a physiological characteristic of the user by extracting a first signal from the impedance measurements, and extracting a second signal from the impedance measurements using the first signal as a timing reference.