Non-invasive Sensor Calibration Device Using Rotating Disk
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Solution Overview
Problem
Existing calibration methods for non-invasive optical sensors, such as pulse oximeters, are costly, time-consuming, and inaccurate due to manufacturing tolerances that cause variations in emitted wavelengths, affecting the accuracy of patient monitoring systems.
Innovation Solution
A calibration device that simulates a patient's pulse using a rotating disk with varying channel depths and widths to generate repeatable and reliable calibration data, utilizing blood samples or models with known parameters to compensate for wavelength variations and improve measurement accuracy across a wider range of values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods using colored films are used, then calibration can be performed, but the process is time-consuming and inaccurate
Solution Approach 1:
The patent creates a digital copy of the calibration curve by measuring absorbance values at multiple wavelengths and storing them in a lookup table. This digital representation replaces the need for physical colored films and manual calibration procedures, enabling rapid and accurate calibration through computational comparison of measured spectra against the stored reference data.
Solution Approach 2:
The patent replaces the mechanical/optical system of physical colored films with an electronic/computational system. Instead of using physical filters and visual matching, the system uses digital storage of calibration data and computational algorithms to perform calibration, eliminating the time-consuming manual processes associated with traditional methods.
2Measurement precision
If LED wavelength variations are not compensated, then device complexity is reduced, but measurement accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the measured spectrum is compared against the stored calibration curve, and calibration factors are adjusted based on the difference. This feedback loop automatically compensates for LED wavelength variations by using the measured spectral characteristics to determine the appropriate calibration offset, maintaining accuracy without requiring complex hardware adjustments.
Solution Approach 2:
The patent compensates for wavelength variations by changing the calibration parameters (absorbance values at specific wavelengths) based on the actual LED emission spectrum. Instead of fixing the wavelength parameter, the system adapts the calibration parameters to match the actual LED characteristics, allowing accurate measurement despite manufacturing tolerances in LED wavelength.
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 calibration device provides reliable and repeatable measurements, enhancing the accuracy of physiological parameter monitoring by compensating for sensor variations and simulating real-world blood conditions, thus improving the fidelity of patient monitoring systems.
Implementation Method 1
The detector is responsive to the emitted light after attenuation by pulsatile blood flowing in the tissue site
Implementation Method 2
a physiological sensor having light emitters and a detector, such as one or more LEDs and a photodetector
Data Source
AI summary
A calibration device according to embodiments of the disclosure is capable of being used with a non-invasive sensor. Certain embodiments of the calibration device simulate a human pulse by varying the volume of blood being measured by the optical sensor. Further, embodiments of the calibration device allow the generation of calibration curves or data for measured parameters over larger ranges of measured values compared to patient-based calibration.