Thermal Mass Flow Sensor Bubble Detection in Infusion Pumps
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Solution Overview
Problem
Existing infusion pump systems rely on pressure-based occlusion detection methods, which are slow and inaccurate, and thermal flow rate sensing methods that are dependent on medication type, leading to potential false-negative bubble detections.
Innovation Solution
A vertically oriented in-line thermal mass flow sensor with a heater and temperature sensors is used to measure the flow rate of fluids in infusion pumps, allowing for the detection of bubbles based on derivatives or ratios of average flow rates, independent of medication type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure-based occlusion detection is used, then the system can detect blockages, but the detection is slow and inaccurate
Solution Approach 1:
The patent replaces pressure-based mechanical detection with thermal mass flow sensing. The thermal sensor measures changes in heat transfer through the fluid, which provides both faster response time and improved accuracy for bubble detection compared to pressure monitoring methods.
2Speed
If thermal flow rate sensing is used, then detection speed improves, but the system becomes dependent on medication type characterization
Solution Approach 1:
The patent changes the detection parameter from flow rate (which varies with medication type) to thermal mass flow, which measures heat transfer characteristics. This parameter change allows the system to detect bubbles based on thermal properties rather than fluid dynamics, making it independent of medication type while maintaining fast detection speed.
3Reliability
If thermal mass flow sensing is used, then bubble detection accuracy improves, but the device complexity increases
Solution Approach 1:
The thermal mass flow sensor serves multiple functions: it measures flow rate, detects bubbles, and identifies retrograde flow. By using a single sensor type for multiple detection purposes, the patent avoids the need for multiple specialized sensors, thereby limiting the increase in device complexity while maintaining high detection accuracy.
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
This solution effectively detects bubbles in infusion pumps, reduces false-negative detections, eliminates medication-type sensitivity, and can detect retrograde flow, enhancing patient safety and infusion pump accuracy.
Implementation Method 1
an in-line thermal mass flow sensor includes a heater and at least one temperature sensor
Implementation Method 2
measuring a flow rate of a fluid flowing through a medical device
Data Source
AI summary
A medical device (10) includes a device housing (12). An in-line thermal mass flow sensor (26) includes a heater (28) and at least one temperature sensor (30). The in-line thermal mass flow sensor is vertically mounted on or in the device housing. The in-line thermal mass flow sensor is configured to measure a flow rate of the fluid through the medical device. At least one electronic processor (18) is programmed to: read the flow rate of the fluid measured by the in-line thermal mass flow sensor; and detect at least one bubble in the fluid based on the measured flow rate.