Variable Orifice Flow Sensor for Anesthesia Gas Monitoring
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Solution Overview
Problem
Existing flow sensors, particularly those with fixed orifices, face challenges in accurately measuring gas flow rates across a wide range, leading to issues with measurement range and sensitivity, and can be affected by moisture, resulting in false readings and the need for separate sensors for different patient types and conditions.
Innovation Solution
A system that includes a processor to obtain usage information from flow sensors, determining the number of breathing cycles and generating alerts for sensor replacement, and detecting condensation, ensuring accurate measurements and preventing sensor malfunction by tracking usage and environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed orifice is used in the flow sensor, then the construction is simple and inexpensive, but the measurement range is limited and cannot accurately measure both low and high gas flow rates
Solution Approach 1:
The patent applies a variable orifice design where the orifice size can dynamically adjust based on flow conditions. The orifice includes a movable component that changes its opening size to optimize measurements across different flow ranges, transforming a static fixed-orifice design into a dynamic system that adapts to varying gas flow rates.
Solution Approach 2:
The patent changes the orifice parameter from fixed to variable by incorporating a movable orifice plate or adjustable aperture mechanism. This allows the system to modify the orifice size parameter in response to detected flow conditions, enabling accurate measurements across both low and high flow rates with a single sensor.
2Measurement precision
If the orifice size is optimized for low flow sensitivity, then adequate obstruction is created for detectable differential pressures, but the measurement range at high gas flows is limited
Solution Approach 1:
The variable orifice mechanism dynamically adjusts the opening size based on detected flow conditions. During low flow conditions, the orifice maintains a smaller opening to provide adequate obstruction and sensitivity. During high flow conditions, the orifice opens wider to accommodate the increased flow rate, thus adapting to different measurement requirements.
Solution Approach 2:
The system performs preliminary detection of flow conditions and adjusts the orifice size in advance to optimize measurements. The control system monitors differential pressure and flow rate indicators, then proactively adjusts the orifice position before measurement errors occur, ensuring optimal sensitivity across the full measurement range.
3Adaptability or versatility
If the orifice size is optimized for high gas flow range, then adequate measurement range is achieved, but sensitivity at low flow rates is insufficient
Solution Approach 1:
The variable orifice system dynamically adjusts its opening size based on the detected flow regime. When high gas flow is detected, the orifice maintains a larger opening to accommodate the flow range. When low flow conditions are detected, the orifice automatically reduces its opening size to increase differential pressure and improve measurement sensitivity.
Solution Approach 2:
The system incorporates feedback mechanisms that continuously monitor differential pressure and flow rate indicators. Based on this feedback, the control system adjusts the orifice position to maintain optimal measurement conditions. The feedback loop ensures that the orifice size is continuously optimized for the current flow conditions, preventing both saturation at high flows and insufficient sensitivity at low flows.
4Device complexity
If a single flow sensor is used for both adult and pediatric patients, then device complexity is reduced, but measurement accuracy varies across different patient types
Solution Approach 1:
The variable orifice flow sensor is designed as a universal device that can accurately measure gas flows for both pediatric and adult patients. The sensor incorporates an adjustable orifice mechanism that can be configured or automatically adjusted to optimize measurements for different patient sizes and flow rates, replacing the need for separate dedicated sensors for different patient populations.
Solution Approach 2:
The system changes the orifice parameter dynamically or through manual configuration to suit different patient types. For pediatric patients with lower flow rates, the orifice is set to a smaller opening to maximize sensitivity. For adult patients with higher flow rates, the orifice is adjusted to a larger opening to accommodate the broader measurement range, all within a single sensor unit.
5Duration of action of moving object
If the flow sensor is used for an extended period of time, then continuous monitoring capability is maintained, but usage information indicates potential accuracy degradation
Solution Approach 1:
The system incorporates feedback mechanisms that continuously monitor usage information including the number of diaphragm movements, total breathing cycles monitored, and accumulated operating hours. When usage thresholds are approached, the system provides feedback alerts to notify users that the sensor may need replacement or recalibration, allowing continuous monitoring while maintaining awareness of potential accuracy degradation.
Solution Approach 2:
The system performs preliminary tracking of usage information and provides advance warning before sensor degradation significantly impacts measurement accuracy. By monitoring diaphragm movement counts and operating duration, the system alerts users in advance to schedule maintenance or replacement, preventing compromised measurements while maximizing the useful service life of the sensor.
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
Enables continuous monitoring of gas flows, provides accurate volume measurements, and prevents sensor malfunctions by proactively replacing or repairing sensors, ensuring reliable patient care across varying patient types and conditions.
Implementation Method 1
uses a restrictor in the gas flow passage to create a pressure drop that can be sensed by a differential pressure transducer
Implementation Method 2
The usage information can include a number of movements of a diaphragm of the first flow sensor
Data Source
AI summary
Techniques described herein can identify usage information for sensors. In one example, an anesthesia device can include a processor to obtain usage information from a first flow sensor coupled to the anesthesia device. The processor can also determine the usage information exceeds a predetermined limit and generate an alert indicating the first flow sensor is to be replaced.