Reflectance Oximetry Sensor with Light Scattering Medium
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Solution Overview
Problem
Pulse oximetry sensors face challenges in attaching to newborns due to their wet skin and tiny anatomical dimensions, making it difficult to obtain accurate and sustained oxygen saturation measurements.
Innovation Solution
A reflectance type pulse oximetry sensor with a light scattering medium, such as a hydrogel, is used to increase the effective detection and emission areas, allowing for better optical coupling and adherence to non-traditional tissue sites like the back or forehead, even when the skin is wet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional pulse oximetry sensor is placed on a newborn's skin, then oxygen saturation measurement is obtained, but the sensor cannot adhere properly due to wet skin (amniotic fluid, meconium, vernix, blood)
Solution Approach 1:
A light-scattering adhesive medium is introduced as an intermediary between the sensor and the newborn's wet skin. This medium serves dual functions: it provides adhesive bonding to hold the sensor in place despite the wet skin conditions, and it scatters light to improve the optical coupling for accurate oxygen saturation measurements. The adhesive medium effectively mediates the interaction between the sensor and the challenging skin environment.
2Measurement precision
If a sensor is placed on a newborn's tiny anatomical dimensions, then measurement is possible, but the effective detection area is insufficient for accurate measurement
Solution Approach 1:
The light-scattering adhesive medium extends the effective detection area by utilizing the dimensional space between the sensor's photodetector and the skin surface. By scattering light in multiple directions within this space, the medium allows photons that would otherwise miss the small photodetector area to be redirected into the detector, effectively increasing the detection area without increasing the physical sensor size.
3Duration of action of stationary object
If a sensor is placed on non-traditional tissue sites (back, forehead), then sustained measurement is achieved, but optical coupling is insufficient
Solution Approach 1:
The light-scattering adhesive medium changes the optical parameters of the measurement system by introducing controlled light scattering. This scattering effect increases the path length of light through the tissue and improves the interaction between light and blood, thereby enhancing the optical coupling and measurement signal even at non-traditional sites like the back or forehead where anatomical constraints prevent optimal sensor placement.
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 sensor effectively measures oxygen saturation by optimizing light transmission and adherence on wet skin, improving signal quality and reliability, especially in newborns where traditional sites are unsuitable.
Implementation Method 1
a light scattering medium configured to contact a tissue site, wherein the light scattering medium is capable of increasing the effective detection area of the one or more photo detectors
Implementation Method 2
a non-invasive sensor that transmits light through a patient's tissue and that photoelectrically senses the absorption and/or scattering of the transmitted light in such tissue
Implementation Method 3
a light emitter disposed in a light barrier, one or more photodetectors disposed outside the light barrier
Data Source
AI summary
A method and apparatus for affixing a sensor adjacent a tissue site is disclosed. In an embodiment, the spectrophotometric sensor comprises, a sensor body, one or more light emitters, one or more photodetectors, and a light scattering medium capable of increasing at least one of the effective detection area of the one or more photodetectors or the effective emission area of the one or more light emitters.