Force-Sensor Flow Tube Detection with Dynamic AC/DC Thresholds
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Solution Overview
Problem
Existing fluid flow systems face challenges in accurately detecting air bubbles and liquid in IV tubes due to variations in ultrasonic signal detection caused by changes in surface contact, tube stiffness, and pressure, leading to inaccurate and erroneous readings.
Innovation Solution
A fluid flow system utilizing a force sensor that monitors both Alternating Current (AC) and Direct Current (DC) components of an output signal, dynamically adjusting a threshold based on factors like sensor position, flow rate, and pressure to enhance detection accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic sensors are used to detect air bubbles in IV tubes, then detection capability is provided, but measurement precision deteriorates due to signal variations caused by surface contact changes, tube stiffness, and pressure
Solution Approach 1:
The system dynamically adjusts the detection threshold based on real-time signal characteristics. The threshold is not fixed but adapts to changing conditions such as surface contact, tube stiffness, and pressure by analyzing the AC component amplitude and DC component signal level, allowing the system to maintain accurate detection despite varying operational conditions
Solution Approach 2:
The system changes the detection parameters by monitoring both AC and DC components of the ultrasonic signal. By analyzing amplitude changes in the AC component and signal level shifts in the DC component, the system transforms the detection approach from using a single fixed threshold to using multiple dynamic parameters that adapt to changing physical conditions
2Measurement precision
If the detection threshold is fixed, then device complexity is reduced, but detection accuracy deteriorates under varying operational conditions
Solution Approach 1:
The system implements feedback by continuously monitoring the AC component amplitude and DC component signal level, then using this information to dynamically adjust the detection threshold. The controller receives feedback from the sensor signals and automatically modifies the threshold to maintain optimal detection accuracy under varying conditions
Solution Approach 2:
The system performs self-adjustment by automatically modifying its own detection threshold based on the analyzed signal characteristics. The controller autonomously adapts the threshold without requiring external intervention or complex manual calibration, allowing the system to serve itself in maintaining optimal detection performance
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 system provides robust and accurate detection of air bubbles and liquid by optimizing frequency range (20 KHz to 1 MHz) and tube compression (10-40% of diameter) for improved signal propagation, reducing errors and enhancing reliability.
Implementation Method 1
one or more sensors such as pressure sensors to detect fluid line blockage and ultrasonic sensors to detect air bubbles present in the IV tube
Implementation Method 2
The controller is configured to monitor a first output signal of a force sensor for a change from the first output signal to a second output signal
Data Source
AI summary
A fluid flow system and a method for detecting air bubble and liquid are provided. The fluid flow system comprises a force sensor configured to monitor at least one of an air bubble or an occlusion in a flow tube. The fluid flow system comprises a controller to execute the method. The controller is configured to monitor an output signal of a force sensor of the fluid flow system, and the output signal comprises an Alternating Current (AC) component and a Direct Current (DC) component, and detect a change in the output signal to a new output signal based on a number of transitions to the new output signal, and a time duration of the new output signal. The controller compares the change in the output signal with one of a predefined number of transitions or a predefined time and determines a new threshold when the change in the output signal exceeds one of the predefined number of transitions or the predefined time.