Wearable IPG-PPG Sensing for Peripheral Vasoconstriction Detection

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Solution Overview

Problem

Existing wearable devices struggle to accurately monitor peripheral vasoconstriction and vasodilation due to factors like temperature changes, posture, hydration, and motion, making it difficult to assess cardiovascular health effectively.

Innovation Solution

A wearable computing device equipped with both impedance plethysmography (IPG) and photoplethysmography (PPG) sensors passively monitors myogenic responses by comparing IPG and PPG data to detect peripheral vasoconstriction and vasodilation, providing insights into cardiovascular health indicators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PPG sensors are used to monitor peripheral blood flow, then cardiovascular health can be monitored, but measurement accuracy deteriorates during vasoconstriction due to reduced blood flow in superficial tissues

Engineering Contradiction:

Improvecardiovascular health monitoringVSAvoidPPG signal accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent combines PPG sensors with IPG sensors to monitor both optical blood flow changes and electrical impedance changes. This merging allows the system to cross-validate measurements and compensate for PPG signal degradation during vasoconstriction, as IPG can detect vascular changes even when optical signals are weakened.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces IPG sensors as an intermediary measurement method that complements PPG sensors. IPG measures electrical impedance changes in tissues, which serves as a mediator to detect vascular changes independently of optical signal quality, thereby resolving the contradiction between PPG monitoring reliability and measurement precision during vasoconstriction.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If ECG sensors are used to monitor cardiovascular health, then electrical activity can be detected, but ease of operation deteriorates as users must actively perform measurements

Engineering Contradiction:

Improvecardiovascular health monitoringVSAvoidmeasurement activation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent implements passive monitoring where the wearable device automatically performs measurements without requiring active user participation. The system continuously monitors PPG and IPG signals during normal wear, making the device self-service oriented and eliminating the need for users to manually activate ECG-like measurements, thereby improving ease of operation while maintaining monitoring reliability.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If multiple sensors are added to improve monitoring accuracy, then measurement precision improves, but device complexity increases

Engineering Contradiction:

Improvemyogenic response detectionVSAvoidsensor configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent designs the wearable device to perform multiple functions using a unified sensor architecture. The PPG and IPG sensors serve multiple purposes: monitoring cardiovascular health, detecting myogenic responses, and providing data for various health metrics. This multi-functionality approach improves measurement precision for myogenic response detection while managing device complexity through shared processing and integrated design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system allows for passive monitoring of cardiovascular health by accurately detecting myogenic responses over time, enabling early detection of conditions like hypertension and diabetes, and providing personalized health recommendations.

Implementation Method 1

the IPG sensor has a pair of excitation electrodes and a pair of sensing electrodes configured to contact the skin of the user, with the IPG sensor being configured to generate IPG data indicative of a voltage passed between the pair of sensing electrodes due to current applied at the pair of excitation electrodes

Methodology Applied

Scientific EffectElectrical Impedance: Electrical Resistance

Implementation Method 2

the PPG sensor may include an emitter configured to emit light and a detector configured to detect the light emitted from the emitter, and where the PPG sensor may be configured to generate PPG data indicative of an amount of light detected by the detector

Methodology Applied

Scientific EffectPhotoplethysmography: Absorption (EM radiation)

Data Source

PatentUS20250375113A1Monitoring Cardiovascular Health Using Sensor Data

Publication Date: 2025.12.11 GOOGLE LLC

AI summary

A computing system, a computer implemented method, and a wearable computing device to determine a cardiovascular response based at least in part on sensor data of a wearable device. For instance, a computing system receives impedance plethysmography (IPG) data generated by an IPG sensor positioned at a lower side of a housing of a wearable device. The computing system receives photoplethysmography (PPG) data generated by a PPG sensor positioned at the lower side of the housing and proximate to the IPG sensor. Then, the computing system determines a cardiovascular response based at least in part on a comparison of the IPG data and the PPG data, such as a peripheral myogenic response.