Magnetic-Flap Optical Sensor for Pulse Oximetry
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Solution Overview
Problem
Conventional pulse oximetry systems face errors due to venous blood movement during patient motion and fail in conditions of low perfusion, intense ambient light, and electrosurgical interference, limiting their accuracy in measuring arterial oxygen saturation and pulse rate.
Innovation Solution
A magnetic-flap optical sensor is designed to attach to a tissue site, using magnetic flaps to occlude blood flow and enhance the pulsatile signal by creating an artificial pulse, thereby improving signal quality and accuracy by blocking ambient light and retaining blood volume within the fingertip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulse oximetry is used to measure arterial oxygen saturation, then basic blood oxygen measurement is achieved, but measurement accuracy deteriorates during patient motion due to venous blood movement
Solution Approach 1:
The sensor is divided into separate functional segments: a finger clip portion that applies mechanical compression to occlude blood flow, and a sensor portion that detects optical signals. This segmentation allows independent optimization of each function - the clip can focus on flow occlusion while the sensor focuses on signal detection, improving measurement accuracy during motion
Solution Approach 2:
The system performs preliminary action by mechanically occluding blood flow in the finger tip before optical measurement occurs. The active pulser creates an artificial pulse that precedes the measurement, and the magnetic flaps pre-position themselves to block ambient light before detection begins. This preliminary preparation ensures accurate measurements even during patient motion
2Measurement precision
If conventional optical sensors are used in low perfusion conditions, then basic detection is maintained, but signal amplitude becomes too small for accurate measurement
Solution Approach 1:
The active pulser performs preliminary action by creating an artificial pulse that mechanically distends the tissue before optical detection. This pre-pulsing action generates a larger amplitude signal that can be accurately detected even in low perfusion conditions where natural pulse signals would be too weak
Solution Approach 2:
The system merges mechanical pulsing functionality with optical detection in a single integrated sensor assembly. The active pulser and optical detectors are combined in one device, allowing the mechanical pulse to directly enhance the optical signal being measured, thereby improving signal amplitude without requiring separate systems
3Measurement precision
If conventional sensors are used in intense ambient light conditions, then basic measurement capability is maintained, but measurement accuracy deteriorates due to light interference
Solution Approach 1:
The magnetic flaps extract and remove the harmful effect of ambient light by physically blocking it from reaching the optical detectors. The flaps are positioned to intercept ambient light paths and exclude this interfering radiation from the measurement zone, allowing accurate detection despite intense external lighting conditions
4Measurement precision
If magnetic flaps are added to occlude blood flow and enhance pulsatile signal, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The magnetic flaps serve multiple functions simultaneously: they occlude blood flow to enhance pulsatile signals, blocks ambient light from reaching detectors, and provide structural support for the sensor assembly. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving multiple performance improvements
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 magnetic-flap optical sensor effectively enhances the accuracy of physiological parameter measurements by accentuating the pulsatile signal, improving performance under conditions that conventional systems struggle with, such as patient movement and low perfusion, and reducing errors caused by venous blood movement.
Implementation Method 1
magnetic flaps extend from an upper one of the pads and are urged against the bottom shell, advantageously occluding blood flow out of the inserted fingertip
Implementation Method 2
The LEDs and detector are attached to a patient tissue site, such as a finger. The cable transmits drive signals from the monitor to the LEDs, and the LEDs respond to the drive signals to transmit light into the tissue site.
Implementation Method 3
The detector generates a photoplethysmograph signal responsive to the emitted light after attenuation by pulsatile blood flow within the tissue site.
Implementation Method 4
The flaps are further configured to create a second squeezing force on side portions of the fingertip. The first and second squeezing forces act to occlude blood flow from the fingertip tissue so as to accentuate the detector signal due to the artificial pulse.
Data Source
AI summary
A magnetic-flap optical sensor has an emitter activated so as to transmit light into a fingertip inserted between an emitter pad and a detector pad. The sensor has a detector responsive to the transmitted light after attenuation by pulsatile blood flow within fingertip so as to generate a detector signal. Flaps extend from the emitter pad and along the sides of a detector shell housing the detector pad. Flap magnets are disposed on the flap ends and shell magnets are disposed on the detector shell sides. A spring urges the emitter shell and detector shell together, so as to squeeze the fingertip between its fingernail and its finger pad. The flap magnets have opposite north and south orientations from the shell magnets, urging the flaps to the detector shell sides and squeezing the fingertip sides. These spring and magnet squeezing forces occlude the fingertip blood flow and accentuate a detector signal responsive to an active pulsing of the fingertip.