Oxygen Sensor Autocorrelation for Fluctuating Pressure
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Solution Overview
Problem
Existing oxygen sensors face challenges in accurately measuring oxygen concentrations in gas mixtures under fluctuating pressure conditions, particularly in medical ventilators, due to the complexity of solving time-variant nonlinear diffusive-convective partial differential equations and the computational intensity of numerical approximation solutions.
Innovation Solution
A method and system that process sensor output signals using autocorrelation to estimate oxygen concentration in gas mixtures with fluctuating pressures, considering cyclostationary pressure variations and using a microprocessor to compute the true oxygen concentration through equations and algorithms that account for pressure fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerical approximation solutions are used to solve time-variant nonlinear diffusive-convective partial differential equations, then measurement precision of oxygen concentration is improved, but device complexity and computational requirements increase significantly
Solution Approach 1:
The patent replaces complex numerical approximation methods for solving partial differential equations with an optical-based sensor system. The amperometric oxygen sensor uses electrochemical reactions and optical detection to directly measure oxygen concentration, eliminating the need for computationally intensive mathematical models while maintaining measurement accuracy under fluctuating pressure conditions.
Solution Approach 2:
The patent changes the measurement parameters by using an amperometric sensor that directly measures oxygen concentration through electrochemical reactions. Instead of solving complex equations, the system measures current generated by oxygen reduction at the cathode, providing a direct and computationally simple method to determine oxygen concentration even when pressure fluctuates.
2Speed
If amperometric oxygen sensor is used to measure oxygen concentration under fluctuating pressure, then response speed is improved, but measurement precision deteriorates due to convective dynamic gas flux
Solution Approach 1:
The patent implements a feedback mechanism where the sensor output signal is continuously monitored and processed. The system uses the sensor's rapid response to detect pressure fluctuations and automatically compensates for their effect on measurement accuracy, maintaining both fast response and precise measurement under dynamic pressure conditions.
3Manufacturing precision
If sensor aperture is designed for diffusion mechanism under steady state, then manufacturing precision is improved, but adaptability to fluctuating pressure conditions deteriorates
Solution Approach 1:
The patent designs the sensor aperture to serve multiple functions: it enables diffusion-based measurement under steady-state conditions while also allowing the sensor to detect and respond to pressure fluctuations. The same aperture structure supports both diffusion-dominated and convection-influenced flow regimes, making the sensor universally applicable across varying pressure conditions without requiring redesign.
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 approach provides a reliable and efficient estimation of oxygen concentration, achieving accuracy within 0-3 percentage points of the actual concentration, even in non-steady pressure environments, by compensating for pressure fluctuations and stabilizing the oxygen concentration measurement.
Implementation Method 1
These sensors are based on the operation of an electrochemical cell in a pumping mode. In particular, the oxygen concentration measurement may be governed by Faraday's law, correlating an output current with the number of oxygen ions passing through an electrolyte
Implementation Method 2
Under steady state pressure conditions and a fixed gas mixture, oxygen molecules may pass through a sensor aperture under a diffusion mechanism
Implementation Method 3
when the gas pressure at the sensor's input aperture is fluctuating, an additional convective dynamic gas flux may arise, causing fluctuation in the number of oxygen molecules reaching the sensor cathode
Data Source
AI summary
A method for estimating the concentration of a particular gas in a gas mixture having a fluctuating pressure is provided. A sensor output signal indicating the concentration of a particular gas in the gas mixture is received from a gas sensor. The received sensor output signal may vary over time due to the fluctuating pressure of the gas mixture. The received sensor output signal may be processed to determine an estimate of the concentration of the particular gas in the gas mixture. The processing may include performing an autocorrelation of the signal. In some embodiments, the particular gas is oxygen and the method is used to estimate the concentration of oxygen in a gas mixture having a fluctuating pressure.