Impedance measurement devices, systems, and methods

• US 9,943,241 B2
• Filed: 07/15/2014
• Issued: 04/17/2018
• 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
• Primary Examiner(s): Eiseman, Adam J
• Assistant Examiner(s): Foreman, Jonathan M
• Application Number:
  US14/332,140
• Publication Number:
  US 20150359441A1
• Time in Patent Office: 1,372 Days
• 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. An apparatus comprising:

an impedance-measurement circuit including a set of electrodes, the impedance-measurement circuit configured and arranged to obtain a plurality of impedance-measurement signals via the set of electrodes while each of the electrodes is concurrently contacting a user, the set of electrodes including a plurality of electrodes configured and arranged in a pattern to mitigate sensitivity to foot placement and for contacting one foot of the user while the user is standing and including at least one other electrode configured and arranged for contacting the user at a location that does not include the one foot, at least one of the impedance-measurement signals being characterized as obtained within the one foot and another of the impedance-measurement signals being characterized as obtained between the one foot and the location that does not include the one foot; and

a second circuit configured and arranged to determine a plurality of pulse characteristic signals based on the plurality of impedance-measurement signals, by determining one of the pulse characteristic signals from one of the impedance-measurement signals and using the one of the pulse characteristic signals as a timing reference to extract and process another of the pulse characteristic signals.

2. The apparatus of claim 1, wherein the second circuit is configured and arranged to determine the plurality of pulse characteristic signals by comparing and assessing the plurality of impedance-measurement signals as part of a signal optimization process.

3. The apparatus of claim 1, wherein:

said at least one other electrode includes at least two electrodes;

the plurality of impedance-measurement signals obtained by the impedance-measurement circuit includes a foot impedance-measurement signal within the one foot and at least two other impedance-measurement signals between the one foot and the location that does not include the one foot that are simultaneously obtained; and

the second circuit is configured and arranged to determine the plurality of pulse characteristic signals by assessing, as part of a signal optimization process, each of the foot impedance-measurement signals and the at least two other impedance-measurement signals.

4. An apparatus comprising:

a base unit including a platform area;

a set of electrodes including a plurality of electrodes configured and arranged in a pattern to mitigate sensitivity to foot placement over the platform area for contacting one foot of a user and including at least one other electrode configured and arranged for contacting the user at a location along a lower limb of the user that does not include the one foot; and

pulse-processing circuitry communicatively coupled to, and configured and arranged with, the set of electrodes to

obtain a plurality of impedance-measurement signals while each of the electrodes is concurrently contacting the user and to determine a plurality of pulse characteristic signals based on the plurality of impedance-measurement signals, at least one of the impedance-measurement signals characterized as being obtained within the one foot and another of the impedance-measurement signals characterized as being obtained between the one foot and the location along a lower limb of the user that does not include the one foot, and

extract one of the pulse characteristic signals from one of the impedance-measurement signals and use the extracted one of the pulse characteristic signals as a timing reference to extract and process another of the pulse characteristic signals.

5. The apparatus of claim 4, wherein the base unit houses the pulse-processing circuitry, the lower limb location of the user is on the other foot, and the pulse characteristic signals indicate pulse arrival times.

6. The apparatus of claim 5, wherein the set of electrodes includes at least four electrodes, and wherein the pulse-processing circuitry is configured to obtain at least four impedance-measurement signals while each of the electrodes is concurrently contacting the user, and to determine the plurality of pulse characteristic signals by comparing at least two of the plurality of impedance-measurement signals and selecting one of the compared impedance-measurement signals over another of the compared impedance-measurement signals.

7. The apparatus of claim 4, wherein the pulse-processing circuitry is further configured to obtain a signal indicative of synchronous information based on the timing reference.

8. The apparatus of claim 4, wherein the pulse-processing circuitry is further configured to obtain a signal indicative of synchronous information based on the timing reference, and wherein the signal containing or indicative of synchronous information corresponds to information in a BCG or impedance cardiogram.

9. The apparatus of claim 4, wherein the pulse-processing circuitry and the set of electrodes are further configured and arranged to introduce an injection impedance signal to the user and to sense, in response, a return impedance signal.

10. The apparatus of claim 4, wherein the plurality of electrodes are further configured and arranged with the pulse-processing circuitry to provide an IPG measurement within the one foot.

11. The apparatus of claim 4, wherein the plurality of electrodes is further configured and arranged in an inter-digitated pattern of positions over the platform, and wherein the pulse-processing circuitry is further configured and arranged to use the inter-digitated pattern of positions to provide an IPG measurement within the one foot.

12. The apparatus of claim 4,

further including current-sourcing circuitry configured and arranged for presenting a plurality of current-injection signals to respective ones of the set of electrodes, with at least one of the current-injection signals modulated for current differentiation,

wherein the plurality of current-injection signals in the set of electrodes includes two injection electrodes, each configured and arranged for imposing current to the user from the current-sourcing circuitry, and

wherein the pulse-processing circuitry is further configured and arranged to sense the plurality of current-injection signals in two distinct body segments of the user.

13. The apparatus of claim 12, wherein the two distinct body segments respectively include a foot segment of the user and a segment including the legs of the user, and wherein the pulse-processing circuitry is configured and arranged to provide leg and foot impedance measurements based on synchronous demodulation of the current-injection signals.

14. The apparatus of claim 4, wherein the set of electrodes includes an electrode pattern element characterized as having a resistivity lower than 300 ohms/square and including at least one of ITO, stainless steel, aluminum and tantalum.

15. The apparatus of claim 4, further including a weighing scale and wherein the base unit is integral with a housing configured and arranged to enclose the weighing scale and the pulse-processing circuitry, the platform area of the base unit providing a user-standing area sufficient for the user to stand with both of the feet of the user on the platform area.

16. The apparatus of claim 4, wherein the set of electrodes includes a pattern of interleaved Kelvin electrode pairs for the one foot.

17. The apparatus of claim 4, wherein the set of electrodes includes a pattern of at least two interleaved Kelvin electrode pairs for the one foot.

18. The apparatus of claim 4, further including BCG sensing circuitry and an electrode pattern element that defines the plurality of electrodes for the one foot, wherein the pulse-processing circuitry is configured and arranged with the BCG sensing circuitry and the electrode pattern element to provide data for measuring arterial pulse wave velocity (“

aPWV data”

) and, in response, to augment the aPWV data with data obtained by BCG sensing.

19. The apparatus of claim 18, wherein the base unit is integral with a housing configured and arranged to enclose a weighing scale and the pulse-processing circuitry.

20. The apparatus of claim 4, wherein the lower limb location is the other foot of the user, wherein the set of electrodes includes a pattern of at least two interleaved Kelvin electrode pairs for the one foot, and wherein the pulse-processing circuitry is configured and arranged to determine the plurality of pulse characteristic signals within 60 seconds from when the user initially stands on the platform area.

21. An apparatus comprising:

a base unit including a platform area;

a set of electrodes including a plurality of electrodes configured and arranged in a pattern to mitigate sensitivity to foot placement over the platform area for contacting a user at a limb extremity, and including at least one other electrode configured and arranged for contacting the user at a different location; and

pulse-processing circuitry communicatively coupled to, and configured and arranged with, the set of electrodes to;

obtain a plurality of impedance-measurement signals while each of the electrodes is concurrently contacting the user, at least one of the impedance-measurement signals being characterized as obtained within the limb extremity and another of the impedance-measurement signals being characterized as obtained between the limb extremity and the different-location,

determine a plurality of pulse characteristic signals based on the plurality of impedance-measurement signals, and

extract one of the pulse characteristic signals from one of the impedance-measurement signals and use the one of the pulse characteristic signals as a timing reference to extract and process another of the pulse characteristic signals.

22. The apparatus of claim 21, wherein the set of electrodes includes a pattern of interleaved Kelvin electrode pairs for the limb extremity, and the limb extremity is a foot and the different location is distal from the foot.

23. The apparatus of claim 21, wherein the set of electrodes includes a pattern of at least two interleaved Kelvin electrode pairs for the limb extremity.

24. The apparatus of claim 21, wherein the limb extremity is a foot and the different location is distal from the foot, and wherein the plurality of electrodes are configured and arranged over the platform area and in a pattern to inject current signals and sense signals in response thereto for a segment of the foot that is common to different foot-to-electrode locations, the different foot-to-electrode locations corresponding to different positions over the platform area where the foot contacts the plurality of electrodes.