iRhythm Technologies, Inc.

The present invention relates to a non-invasive cardiac monitoring device that records cardiac data to infer physiological characteristics of a human, such as cardiac arrhythmias or other vital signs. Some examples of the invention allow for long-term monitoring of physiological signals. Further examples allow for processing of ECG and PPG data to calculate pulse arrival time. Some examples include a wearable cardiac monitor device on a chest that includes both the ECG and PPG sensor for long-term adhesion to a mammal for prolonged detection of cardiovascular signals.

The present disclosure relates to a wearable monitor device and methods and systems for using such a device. In certain embodiments, the wearable monitor records cardiac data from a mammal and extracts particular features of interest. These features are then transmitted and used to provide health-related information about the mammal.

Activity level and fall detection using accelerometer data is described. In one or more implementations, measurements of a user generated by a wearable monitoring device during an observation period are obtained, the measurements including accelerometer data. Physical steps taken by the user are detected based on peaks in the accelerometer data above a threshold, and a step count is generated based on the detected physical steps within predetermined time epochs. Activity level classifications of the user for the predetermined time epochs are generated based on the step count. The step count and the activity level classification for the predetermined time epochs may then be output, such as a notification or in a user interface. Fall predictions may be generated and output by processing the accelerometer data using machine learning models trained to correlate patterns in accelerometer data to fall events.

Techniques for conduction-based contact detection for physiological sensors are described. In an example, a wearable device includes a contact-based sensor configured to collect physiological data of a user and at least one electrode positioned proximate to the contact-based sensor, such that a contact status of the electrode corresponds to a contact status of the sensor. The wearable device includes a contact detection circuit that is configured to determine a contact condition of the contact-based sensor that indicates whether the sensor is in sufficient contact with the skin surface based on an electrical characteristic of a conduction path between the at least one electrode and a skin surface of the user. In this way, the techniques described herein support reliable detection of sensor contact quality through conduction-based measurements, which enables wearable devices to ensure accurate physiological data collection while optimizing power consumption and improving an overall user experience.

Techniques for conduction-based contact detection for physiological sensors are described. In an example, a wearable device includes a contact-based sensor configured to collect physiological data of a user and at least one electrode positioned proximate to the contact-based sensor, such that a contact status of the electrode corresponds to a contact status of the sensor. The wearable device includes a contact detection circuit that is configured to determine a contact condition of the contact-based sensor that indicates whether the sensor is in sufficient contact with the skin surface based on an electrical characteristic of a conduction path between the at least one electrode and a skin surface of the user. In this way, the techniques described herein support reliable detection of sensor contact quality through conduction-based measurements, which enables wearable devices to ensure accurate physiological data collection while optimizing power consumption and improving an overall user experience.

A replaceable overpatch with embedded sensors is described to attach a main body of a wearable device to a skin surface of a user. For example, the main body houses a processing circuit to process physiological data collected by the embedded sensors of the overpatch. A bottom surface of the main body is configured to face the skin surface during wear and a top surface opposite the bottom surface includes a body connection interface. The overpatch is dimensioned to be placed over the main body to secure the main body to the skin surface and includes an overpatch connection interface that is dimensioned to mate with the body connection interface to form an electrical connection between the overpatch and the main body. In this way, physiological data collected by the embedded sensors can be communicated to the processing circuit without interference caused by proximity to the skin surface.

Techniques for physiological monitoring using low sample rate accelerometer data are described and are implementable to generate insights related to user states during extended wear periods. In an example, low sample rate accelerometer data having a sample rate that is below a sample rate threshold is received from a wearable device mounted on a skin surface of a chest region of a user during a wear period. The low sample rate accelerometer data is processed to extract one or more motion-derived parameters that characterize temporal movement patterns of the user during the wear period. An insight for presentation related to a user state during the wear period is generated based on the one or more motion-derived parameters. The insights can include but are not limited to predictions of sleep states, active states, and inactive states, body angle and position determinations, and detection of device inversion events.

Techniques for cuffless blood pressure monitoring with multiparameter correction are described and are implementable to reduce measurement inaccuracies in wearable cuffless blood pressure devices. In an example, a wearable device includes a sensor arrangement to collect physiological timing data indicative of a pulse propagation time along a cardiovascular pathway and a correction sensor that is configured to measure a correction parameter that impacts the pulse propagation time independent of a corresponding change to blood pressure, such as body temperature, skin temperature, perfusion index, hydration level, or muscle activation.  A processor of the wearable device is configured to process the physiological timing data to determine the pulse propagation time and generate a blood pressure measurement based on the pulse propagation time and measurements of the correction parameter.  Accordingly, the techniques described herein generate blood pressure measurements that account for physiological variables that have an independent impact on pulse propagation characteristics.

A cardiac monitoring system with sleep and activity correlation is described. In one or more implementations, measurements of a user generated by a wearable monitoring device during an observation period are obtained, the measurements including accelerometer data and electrical potential measurements. Sleep periods and wake periods are detected based on the accelerometer data. Sleep stage classifications and activity level classification are generated based on the accelerometer data during the detected sleep periods. The electrical potential measurements are processed using a machine learning model trained to correlate patterns in the electrical potential measurements to cardiac rhythm classifications. Arrhythmia correlations may be generated and output based on the sleep stage classifications and the activity level classifications and concurrent cardiac rhythm classifications. The arrhythmia correlations may describe temporal relationships between detected cardiac arrhythmias and specific sleep stages of the sleep stage classifications and may be output in a health report.

The present disclosure relates to a device configured to be adhered to the surface of a mammal for recording physiological signals. The device may include a housing enclosing a circuit board and a flexible wing extending from the housing. The device may include an electrode coupled to the flexible wing and an electrical trace for transmitting an electrical signal between the electrode and the circuit board. The electrical trace may have an insulator with a conductive material and resistors printed on the surface of the insulator. The trace layer may include conductive vias for transmitting the signal from a bottom of the trace layer to a top of the trace layer. The housing may include a battery having a battery terminal connector configured to provide electrical access to both terminals on a single side of the battery. The housing may include a floating trigger button.