Chest Patch Sensor Using Heated PPG for Cuffless Hemodynamics

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Solution Overview

Problem

Existing physiological monitoring devices are cumbersome, invasive, and require multiple machines, leading to inefficiencies and discomfort for patients, particularly when measuring vital signs and hemodynamic parameters over extended periods.

Innovation Solution

A chest-worn patch sensor that non-invasively measures HR, HRV, RR, SpO2, BP, SV, CO, and FLUIDS using ECG, IPG, and PPG waveforms, with integrated heating to enhance perfusion and reduce motion artifacts, wirelessly transmitting data to external gateways for integration with hospital systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional cuff-based blood pressure measurement and multiple separate machines are used, then measurement accuracy can be maintained, but device complexity and patient discomfort increase significantly

Engineering Contradiction:
Improvepatient comfortVSAvoidnumber of machines
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines multiple physiological measurement functions (ECG, PPG, impedance plethysmography, temperature sensing) into a single integrated patch sensor device. This consolidation eliminates the need for multiple separate machines and reduces patient discomfort by using a unified, wearable patch instead of multiple discrete devices.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patch sensor is designed to perform multiple measurement functions simultaneously - cardiac monitoring (ECG), oxygen saturation (PPG), fluid status (impedance plethysmography), and temperature monitoring - all within a single universal device that can be worn continuously on the patient's body.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If disposable electrodes with cables and leads are used, then ECG and IPG waveform measurement accuracy is maintained, but ease of operation and patient comfort deteriorate

Engineering Contradiction:
Improvewaveform measurement accuracyVSAvoidease of use
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the mechanical cable-and-lead connection system with a wireless transmission system. The patch sensor wirelessly transmits physiological data to external monitoring systems, eliminating the need for physical cables and leads that connect electrodes to monitoring equipment, thereby improving ease of use while maintaining measurement accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the cumbersome cable and lead components from the measurement system. By using wireless communication, the physical connection elements that complicate the system are completely removed, leaving only the lightweight patch sensor that can be easily applied and removed.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If optical sensors measure PPG waveforms without heating, then device simplicity is maintained, but measurement precision deteriorates due to reduced perfusion

Engineering Contradiction:
ImprovePPG signal qualityVSAvoidsensor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies localized heating to the measurement site to increase blood perfusion and improve PPG signal quality. By controlling the temperature parameter at the sensor-tissue interface, the system enhances the optical signal strength and measurement precision without fundamentally changing the overall sensor structure.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If continuous monitoring is implemented, then reliability of physiological parameter assessment improves, but use of energy increases

Engineering Contradiction:
Improvecontinuous monitoring capabilityVSAvoidbattery consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patch sensor implements periodic measurement cycles rather than truly continuous monitoring. The optical sensor and other measurement components operate in periodic bursts, collecting physiological data at intervals sufficient to assess trends and detect changes while allowing energy-consuming components to remain inactive between measurements, thereby reducing overall power consumption.

Inventive Principle:
Principle #19Periodic action

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 patch sensor provides continuous, accurate, and comfortable monitoring of vital signs and hemodynamic parameters, reducing motion artifacts and enhancing patient compliance by minimizing discomfort and obtrusiveness, while achieving high signal-to-noise ratios and reducing the need for traditional cuff-based measurements.

Implementation Method 1

A heating element on the bottom surface of the patch sensor contacts the patient's chest and gently warms the underlying skin, thereby increasing perfusion of the tissue.

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

A photodetector detects the reflected radiation in the different spectral ranges to generate analog red-PPG and infrared-PPG waveforms.

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3826533B1Patch-based physiological sensor
Publication Date: 2025.12.03 BAXTER INT INC
  • EP3826533B1 patent drawingFigure 1
  • EP3826533B1 patent drawingFigure 2A~2B
  • EP3826533B1 patent drawingFigure 3A~3B

AI summary

The invention provides a body-worn patch sensor for simultaneously measuring a blood pressure (BP), pulse oximetry (SpO2), and other vital signs and hemodynamic parameters from a patient. The patch sensor features a sensing portion having a flexible housing that is worn entirely on the patient's chest and encloses a battery, wireless transmitter, and all the sensor's sensing and electronic components. It measures electrocardiogram (ECG), impedance plethysmogram (IPG), photoplethysmogram (PPG), and phonocardiogram (PCG) waveforms, and collectively processes these to determine the vital signs and hemodynamic parameters. The sensor that measures PPG waveforms also includes a heating element to increase perfusion of tissue on the chest.