Simultaneous monitoring of ECG and bioimpedance via shared electrodes
Inventors
Trapero Martin, Ana • VERMEER, Michael Daniel • Asselin, Mathew • Ironstone, Joel Steven • Reykhert, Alexey
Assignees
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Publication Number
US-11154204-B2
Publication Date
2021-10-26
Expiration Date
Abstract
A system for acquiring electrocardiograph (ECG) and bioimpedance (BI) data is disclosed. The system (an ECG/BI measurement system) can use as few as one or two pairs of electrodes, permitting wearable devices employing the ECG/BI measurement system to be made into smaller, more comfortable, and more inconspicuous formats, as well as decreasing potential failure points in the measurement of electrical signals conducted between the system and the user. The system can measure both ECG and BI data using at least one shared pair of electrodes. In some cases, ECG and BI data are separately extracted from a measured signal across a shared pair of electrodes, while another pair of electrodes is being driven with a supply current. In other cases, internal switching can automatically switch a pair of electrodes between ECG-measuring circuitry and BI-measuring circuitry, such as based on a clock signal or other trigger.
Core Innovation
The invention relates to an electrocardiogram (ECG) and bioimpedance (BI) wearable device that includes first and second pair of electrodes arranged in a linear array. A control system is coupled to the electrode pairs and includes ECG processing circuitry, BI processing circuitry, and a controllable switch to selectively direct a sensed signal to the ECG processing circuitry or the BI processing circuitry. In the ECG mode, ECG measurements are determined from a sensed signal directed to the ECG processing circuitry by determining an ECG signal from the sensed signal directed to the ECG processing circuitry.
In the BI mode, the controllable switch is actuated and an injection current is provided via the first pair of electrodes at a frequency that is at or greater than a minimum injection frequency. The sensed signal acquired via the second pair of electrodes is directed to the BI processing circuitry and a BI signal is determined from the sensed signal directed to the BI processing circuitry. In certain schemes, ECG and BI are extracted from a single sensed signal while injection current is applied, and in other schemes the device alternates between ECG and BI by switching routing between ECG circuitry and BI circuitry.
The invention further provides ECG/BI signal processing concepts in which sensed signals are separated using filtering, and the BI signal is down-converted for processing. The down-converted BI signal is processed to extract BI measurements, including configurations where the BI signal is down-converted to a frequency at or below both the minimum injection frequency and 1 kHz or to a frequency at or below 1 kHz. The wearable device is implemented as a patch architecture with an electronics module and electrode pairs embedded in a patch substrate, including an adhesive layer for skin coupling and, in certain implementations, conductive hydrogel or conductive gel on exposed electrode surfaces.
Claims Coverage
The document provides three independent claims covering (i) a system with selectable routing between ECG and BI processing from linear-array electrode pairs, (ii) a method that alternates switch actuation to route the sensed signal and provide injection current for BI, and (iii) a system that derives ECG and BI from the sensed signal with BI down-conversion to constrained frequencies. Across the independent claims, the main inventive themes are shared electrode architecture in a linear array and controlled selection of ECG vs BI processing including injection-current frequency constraints and BI down-conversion.
Selectable ECG/BI processing with linear-array electrode pairs and controllable switch
A system including a first pair of electrodes and a second pair of electrodes arranged in a linear array, and a control system with ECG processing circuitry, BI processing circuitry, and a controllable switch coupled to the second pair of electrodes to selectively direct a sensed signal to the ECG processing circuitry or the BI processing circuitry, wherein the control system acquires the sensed signal via the second pair of electrodes and determines ECG measurements and BI measurements from the sensed signal based on the routing.
BI injection-current provisioning at or above a minimum injection frequency during BI routing
A system wherein determining BI measurements includes actuating the controllable switch, providing an injection current via the first pair of electrodes in response to actuating the controllable switch, with the injection current provided at a frequency at or greater than a minimum injection frequency, directing the sensed signal to the BI processing circuitry, and determining a BI signal from the sensed signal directed to the BI processing circuitry.
Alternating switch actuation to route sensed signals between BI and ECG processing
A method that actuates a controllable switch a first time to direct a sensed signal acquired by a second pair of electrodes to BI processing circuitry and, in response to the first time actuation, provides injection current via a first pair of electrodes at a frequency at or greater than a minimum injection frequency with the first pair and the second pair arranged in a linear array to determine BI measurements, then actuates the controllable switch a second time to direct the sensed signal to ECG processing circuitry and determine ECG measurements.
Down-converting the BI signal to frequencies at or below minimum injection frequency and 1 kHz
A system that provides injection current via the first pair of electrodes at or greater than a minimum injection frequency, acquires a sensed signal via the second pair of electrodes, determines an ECG signal and a BI signal from the sensed signal, down-converts the BI signal to a frequency at or below both the minimum injection frequency and 1 kHz, and processes the down-converted BI signal to extract the BI measurements.
Overall, the independent claims focus on ECG/BI sensing using first and second linear-array electrode pairs with selectable routing between ECG processing circuitry and BI processing circuitry, BI injection current provided at or above a minimum injection frequency, and BI processing that includes down-converting the BI signal to frequency constraints before extracting BI measurements.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Blood glucose monitoring using ECG features and/or BI measurements including BI spectroscopy and combining ECG- and impedance-based glucose estimates.
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