Pulsed Laser Vibrometer for Noninvasive Cardiac Monitoring
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Solution Overview
Problem
Existing non-invasive cardiac monitoring technologies, such as laser vibrometers, are suboptimal for accurately detecting cardiac mechanical functions and timing errors due to limitations in precision and sensitivity, especially when monitoring cardiovascular activity remotely and non-invasively.
Innovation Solution
A remote, non-invasive monitoring system using a pulsed laser vibrometer with an interferometric setup, including a photo-EMF detector and amplifier, optimized for detecting minute displacements caused by cardiac pulsations, allowing for precise monitoring of heart function without direct contact with the patient's chest, and capable of operating through clothing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional laser vibrometers are used for non-invasive cardiac monitoring, then the monitoring can be performed remotely and non-invasively, but the precision and sensitivity for detecting cardiac mechanical functions and timing errors are insufficient
Solution Approach 1:
The system segments the detection process by using multiple discrete optical components (beam splitter, reference mirror, telescope optics, photo-EMF detector) arranged in a modular interferometric configuration. Each component performs a specific function in the optical path, allowing the complex measurement task to be divided into manageable segments that collectively achieve high precision detection of cardiac vibrations.
Solution Approach 2:
The patent introduces an interferometric setup as an intermediary system between the cardiac source and the detector. This intermediary uses optical interference patterns to amplify and translate minute cardiac vibrations into measurable signal variations, thereby achieving high measurement precision without direct contact with the patient.
2Measurement precision
If existing laser vibrometers are used, then non-contact monitoring is achieved, but the signal-to-noise ratio is insufficient for detecting picometer-scale displacements
Solution Approach 1:
The system exploits mechanical vibration detection by using the interferometric setup to detect minute vibrations of the patient's skin surface caused by underlying cardiac activity. The optical interference pattern responds to these mechanical vibrations, converting them into measurable intensity variations that reveal cardiac mechanical functions with picometer-scale sensitivity.
Solution Approach 2:
The patent employs parameter changes in the optical system by varying the interferometric configuration and using a pulsed laser source with specific temporal characteristics. These parameter changes optimize the system's response to cardiac vibrations while suppressing noise, thereby improving the signal-to-noise ratio for detecting picometer-scale displacements.
3Ease of operation
If contact-based monitoring devices are used, then accurate cardiac electrical activity measurement is achieved, but direct contact with the patient's chest is required
Solution Approach 1:
The patent replaces the mechanical contact-based ECG electrode system with an optical non-contact laser vibrometer. This substitution uses light-based interferometric detection to measure cardiac-induced surface vibrations, eliminating the need for physical contact while achieving comparable or superior measurement precision for cardiac mechanical functions.
Solution Approach 2:
The system utilizes the periodic nature of cardiac vibrations to enhance detection accuracy. By synchronizing the pulsed laser operation and signal processing with the expected periodic frequency of cardiac cycles, the system accumulates signal information over multiple cycles, improving measurement precision despite the non-contact approach.
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 enhances the precision and accuracy of cardiac function monitoring, enabling early detection of heart defects and subtle changes in cardiovascular activity, even in challenging environments, with improved signal-to-noise ratio and sensitivity to picometer-scale displacements.
Implementation Method 1
A remote, non-invasive system is disclosed for monitoring the functionality of a region of interest ("ROI") using reflected laser return signals
Implementation Method 2
The present system is configured to accurately detect the minute displacements in real-time as amplified vibration signals
Implementation Method 3
A remote, non-invasive system is disclosed for monitoring the functionality of a region of interest ("ROI") using reflected laser return signals
Data Source
AI summary
A system for monitoring vibrations in a target region of interest may include a pulsed laser transmitter assembly, interferometric, telescope, and receiver optics, a photo-EMF detector assembly, signal conditioning/processing electronics, and a monitoring circuit/display. The detector assembly, which has a photo-EMF detector and amplifier circuits, generates an output signal indicative of the vibrations. A laser module outputs a source beam at a PRF of at least 2 Hz. A beam splitter device splits the source beam into separate interrogating and reference beams. The mirror directs the reference beam onto the photo-EMF detector for interference with a reflected return signal. The telescope optics generates an amplified return signal, and directs the amplified return signal to the photo-emf detector. The monitoring computer compares the output signal from the signal processor to a baseline to ascertain a difference therebetween, and generates a diagnostic signal indicative of the difference.