Wearable Laser Doppler Blood Flowmeter Without Optical Fibers
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Solution Overview
Problem
Current blood flow measurement techniques, such as Doppler ultrasound and magnetic resonance imaging, are invasive, costly, or prone to errors, and existing wearable devices like laser Doppler flowmeters are limited by optical fiber movement and require medical supervision.
Innovation Solution
A wearable system using a laser Doppler effect with a miniaturized blood flowmeter that integrates a laser diode, photodiode, and analog front-end on a PCB, enabling continuous blood flow monitoring without optical filters or fibers, and operates in voltage or frequency modes based on current magnitude, reducing noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser Doppler flowmeters use optical fibers and aligned optical components, then measurement precision is improved, but device complexity increases and movement artifacts occur
Solution Approach 1:
The patent combines the laser source, optical components, and detection elements into an integrated probe assembly where the LED and photodetector are positioned in fixed geometric relationship. This merging eliminates the need for separate optical fibers and complex alignment mechanisms while maintaining measurement capability through the integrated structure.
Solution Approach 2:
The integrated probe serves multiple functions: the LED emits light, the photodetector collects scattered light, and the fixed geometric arrangement provides both illumination and detection pathways. This multi-functional design replaces multiple specialized optical components with a single unified structure that performs all necessary functions.
2Measurement precision
If conventional blood flow measurement devices are used, then measurement capability is achieved, but portability and ease of operation deteriorate due to hospital-only availability
Solution Approach 1:
The system is segmented into a portable measurement unit with integrated optics and electronics, separated from the need for hospital infrastructure. The probe can be independently used at the patient's location, enabling home-based monitoring without requiring centralized medical equipment.
Solution Approach 2:
The device is designed for self-service operation by patients or caregivers without requiring physician supervision. The integrated design includes all necessary components (light source, detector, signal processing) in a single portable unit that can be operated independently of hospital facilities.
3Measurement precision
If optical fibers are used in laser Doppler flowmeters, then signal-to-noise ratio is improved, but dynamic artifacts increase due to fiber movement
Solution Approach 1:
The light source and detector are merged into a single integrated probe assembly with fixed internal geometry. This eliminates optical fibers entirely, as the light path is defined by the fixed spatial relationship between the LED and photodetector within the probe, removing the source of movement-induced artifacts.
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 provides accurate, continuous blood flow monitoring capable of detecting tiny velocity variations, reducing dynamic artifacts, and is compact enough for home use, allowing early diagnosis of conditions like PAD without medical supervision.
Implementation Method 1
wearable system using a laser Doppler effect
Implementation Method 2
LDFs use optical fibers as a spatial filter to conduct the laser light to skin tissues and pass the collected reflected signal
Implementation Method 3
pass the collected reflected signal to a photo detector
Data Source
AI summary
Provided are methods and devices for blood flow measurement.