PCB Heating Elements for Infusion Fluid Warmers
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Solution Overview
Problem
Existing infusion fluid warmers suffer from inefficient heating due to low thermal conductivity of polymers used in their construction, leading to slow and inefficient temperature control of infusion fluids, which is critical for patient safety during medical procedures.
Innovation Solution
The design incorporates a heat exchanger with first and second printed circuit boards featuring integrally formed electrically resistive patterns that are thermally connected to the heat exchanger walls, allowing for precise control of temperature by selectively connecting a DC power supply to these patterns based on resistance measurements, enhancing thermal conductivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer materials are used in the infusion fluid warmer construction, then ease of manufacture and cost are improved, but thermal conductivity deteriorates leading to slow and inefficient heating
Solution Approach 1:
The patent employs composite material construction by integrating PCB heating elements (electrically conductive traces on insulating substrate) with polymer housing components. The PCB serves dual function as structural element and heating element, while the polymer provides insulation and structural support. This composite approach maintains ease of manufacture with standard PCB and plastic injection molding processes while achieving adequate thermal transfer through the thin PCB structure directly contacting the fluid passage.
Solution Approach 2:
The heating function is localized to specific regions where the PCB traces are positioned adjacent to the fluid passage. The insulating substrate of the PCB provides thermal isolation in areas not requiring heating, while the conductive traces provide localized heating exactly where needed. This local quality approach optimizes thermal efficiency without requiring the entire polymer structure to have high thermal conductivity.
2Measurement precision
If PCB heating elements are used, then temperature control accuracy is improved, but device complexity increases due to integration of heating and insulation functions
Solution Approach 1:
The patent merges multiple functions into the PCB component: the insulating substrate provides thermal and electrical insulation, the conductive traces provide heating function, and the overall PCB structure serves as a structural support element. This consolidation reduces part count and assembly complexity compared to separate heater elements mounted within polymer housing, while maintaining precise temperature control through direct thermal coupling with the fluid passage.
Solution Approach 2:
The PCB serves multiple functions simultaneously: structural support for the fluid passage, thermal insulation through its substrate, electrical heating through its traces, and temperature sensing integration point. This multi-functionality reduces the number of separate components needed, simplifying the overall device structure while achieving accurate temperature control through integrated sensing and heating capabilities.
3Reliability
If thicker polymer walls are used for insulation, then thermal insulation is improved, but heating response time deteriorates due to increased thermal resistance
Solution Approach 1:
The patent optimizes the thickness parameter of the PCB substrate to achieve the right balance between insulation and thermal transfer. The substrate is thick enough to provide adequate electrical and thermal insulation from surrounding components, yet thin enough to allow efficient heat transfer from the conductive traces to the fluid passage. This parameter optimization enables reliable thermal insulation while maintaining fast heating response time.
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 provides a more responsive and accurate temperature control of infusion fluids, reducing the risk of hypothermia and improving the reliability, energy efficiency, and cost-effectiveness of the infusion fluid warmer, making it suitable for field use.
Implementation Method 1
The integrally formed electrically resistive patterns are heated by supply of electrical power
Implementation Method 2
thermally coupled to a heat exchanger to warm an infusion fluid flowing through a fluid passage of the heat exchanger
Data Source
AI summary
The present invention relates to an infusion fluid warmer comprising a heat exchanger and first and second printed circuit boards comprising respective integrally formed electrically resistive patterns acting as heating elements. The integrally formed electrically resistive patterns are heated by supply of electrical power and thermally coupled to a heat exchanger to warm an infusion fluid flowing through a fluid passage of the heat exchanger.