Fetal Oximetry Sensor with Deployable Wings
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Solution Overview
Problem
Fetal pulse oximetry sensors face challenges in maintaining accurate readings due to short light pathlength through the tissue, leading to poor signal-to-noise ratios and erroneous measurements, while also requiring a large sensor size for adequate pathlength, which complicates early placement during labor.
Innovation Solution
A fetal oximetry sensor with a helical needle and deployable wings that allow for subcutaneous light delivery and optimal light emitter to photodetector separation, enabling accurate photoplethysmographic measurements while minimizing sensor size for early placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor size is increased to provide adequate light pathlength through the tissue, then the signal-to-noise ratio is improved, but the difficulty of early placement during labor increases due to excessive cervical dilation requirements
Solution Approach 1:
The sensor is divided into two functional segments: a small insertion portion that passes through the cervix and a deployed portion that provides adequate light pathlength. The deployable wings are collapsed during insertion to minimize sensor profile, then deployed after placement to achieve the required emitter-detector separation distance for accurate measurements.
Solution Approach 2:
The sensor incorporates deployable wings that can transition from a collapsed state during insertion to an expanded state during operation. This dynamic transformation allows the sensor to adapt its size: compact for passing through the cervix, then expanded to provide sufficient tissue pathlength for high signal-to-noise ratio measurements.
2Volume of moving object
If the light emitter and photodetector are placed on the same surface of the tissue, then the sensor size is minimized, but light may be shunted directly from the emitter to the detector without passing through the tissue, causing erroneous readings
Solution Approach 1:
The sensor utilizes the third dimension by deploying wings outward from the sensor body after insertion. This dimensional transition allows the photodetector to be positioned at an optimal distance from the light emitter while maintaining a compact insertion profile, ensuring light passes through adequate tissue depth without direct shunting.
Solution Approach 2:
The deployable wings act as intermediaries that position the photodetector at the correct distance from the light emitter. The wings provide the necessary separation to prevent direct light shunting while maintaining proper optical alignment, ensuring accurate photoplethysmographic measurements.
3Ease of operation
If the sensor is made compact for early placement, then the ease of operation is improved, but the light pathlength through the tissue is reduced, leading to poor signal-to-noise ratio
Solution Approach 1:
The sensor separates the insertion function from the measurement function. The insertion portion remains compact for easy passage through the cervix, while the measurement portion (with deployed wings) provides adequate light pathlength for high signal-to-noise ratio photoplethysmographic measurements.
Solution Approach 2:
The sensor dynamically changes its configuration from a compact inserted state to an expanded measuring state. During insertion, the wings are collapsed to minimize size for easy placement. After positioning, the wings deploy to create the necessary light pathlength through the tissue for accurate measurements with high signal-to-noise ratio.
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 achieves high signal-to-noise ratios and accurate measurements by optimizing light pathlength through the tissue with deployable wings, allowing for early placement during labor without the need for excessive cervical dilation.
Implementation Method 1
One or more optical fibers running through the inside of the helical needle deliver light to the tip of the needle where it is emitted into the fetal tissue.
Implementation Method 2
a photodetector that measures the intensity of the light exiting the tissue-under-test at the sensor site
Data Source
AI summary
A photoplethysmographic sensor designed for use on the presenting portion of a fetus during labor and delivery. The sensor has a non-deployed state in which the sensor presents a smaller footprint, or cross sectional area, for transvaginal insertion. Once the sensor is applied to the fetal tissue it is moved into the deployed state, which has a larger footprint or cross sectional area, than the sensor does in the non-deployed state. The deployed state optimizes the physical distance between the light emitter and the photodetector to maximize the photoplethysmographic measurement accuracy from the fetal tissue.