Blood Flow Meter Circumferential Sensor Accuracy
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Solution Overview
Problem
Existing blood flow meters are unable to accurately measure the mass flow rate of blood flow in a blood vessel due to the temperature sensing member being positioned on the outer surface of a stainless steel tube, which only detects information near the inner wall and at specific positions, potentially leading to incorrect measurements.
Innovation Solution
A blood flow meter with a hollow shaft and a flow rate sensor having a heating resistor spirally wound in a coil shape, accommodated in an element holding body with a thermal conductive insulating member, allowing temperature changes to be detected over the entire circumference, enabling accurate measurement of mass flow rate changes across the blood vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature sensing member is provided on the outer peripheral surface side of the stainless steel outer tube, then the structure is simple and easy to manufacture, but the measurement precision of mass flow rate is insufficient because only local information near the inner wall can be acquired
Solution Approach 1:
The temperature sensing member is divided into multiple independent temperature sensing elements arranged around the circumference of the inner cavity. Each element detects temperature at a specific angular position, and the combined data from all segments provides comprehensive circumferential temperature distribution information, enabling accurate mass flow rate measurement throughout the blood vessel cross-section.
Solution Approach 2:
The sensing arrangement transitions from a single-point measurement on the outer surface to a multi-dimensional array of temperature sensing elements distributed around the inner cavity circumference. This spatial distribution in the radial and angular dimensions allows capture of temperature variations across the entire blood vessel cross-section, resolving the limitation of local-only measurement.
2Measurement precision
If the temperature sensing member is positioned at a predetermined position in the circumferential direction, then the device structure is simplified, but the measurement accuracy is reduced because only blood flow information at that specific position can be acquired
Solution Approach 1:
The temperature sensing member consists of multiple discrete temperature sensing elements positioned at different angular positions around the inner cavity. Each element independently measures temperature at its specific location, and the aggregation of these segmented measurements provides comprehensive blood flow information across the entire circumferential direction, eliminating position-specific measurement limitations.
Solution Approach 2:
The array of temperature sensing elements collectively performs the function of measuring blood flow characteristics at multiple circumferential positions simultaneously. This multi-functional arrangement allows the single sensor assembly to capture comprehensive blood flow data across the entire vessel cross-section, making the device universally applicable for accurate mass flow rate measurement regardless of blood flow distribution patterns.
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 solution allows for high-accuracy measurement of the mass flow rate of blood flow along the entire circumference and length of the blood vessel, improving the accuracy of coronary flow reserve calculations and overall coronary circulation assessment.
Implementation Method 1
a flow rate sensor which has a measurement element containing a heating resistor having a temperature-resistance characteristic
Implementation Method 2
a thermal conductive insulating member disposed between the flow rate sensor and the element holding body in the element holding body
Implementation Method 3
the measurement element can detect the temperature changes in the peripheral wall of the element holding body over the entire circumference
Data Source
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AI summary
[Problem] To provide a blood flow meter capable of measuring the flow rate of the blood flow with high accuracy in a blood vessel of a living body. [Solution] An element holding body 14 having a tubular shape and having an outer diameter smaller than or equal to the outer diameter of a hollow shaft 12, which has flexibility and is insertable into a blood vessel, is provided on the distal side of the shaft 12 so as to be coaxial with the shaft 12. A flow rate sensor 21 is accommodated in the element holding body 14. The flow rate sensor 21 has a measurement element 22 in which a nickel wire is spirally wound to be formed into a coil shape so that adjacent nickel wires are not in contact with each other and are insulated. A thermal conductive insulating member 25 is provided between the flow rate sensor 21 and the element holding body 14 in the element holding body 14 and the flow rate sensor 21 is fixed in the element holding body 14 by the insulating member 25.