Self-regulating Flexible Heating Device with Double-sided Polymer Circuitry
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Solution Overview
Problem
Existing resistive heating devices are complex and costly due to the inclusion of control electronics with integrated circuits on rigid printed circuit boards, which increases complexity and reduces efficiency.
Innovation Solution
The development of a self-regulating flexible heating device with printed heating elements and bus bars on opposite sides of a flexible film substrate, utilizing positive temperature coefficient ink and conductive vias for efficient current transfer, reducing material costs and weight while allowing for more efficient heat distribution and fault-tolerant designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If control electronics with integrated circuits on rigid printed circuit boards are used, then heating control functionality is achieved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the control electronics from the heating device by utilizing the self-regulating properties of PTC ink. Instead of using separate control circuits and integrated circuits, the PTC material inherently provides temperature-dependent resistance control, eliminating the need for complex external control systems while maintaining heating functionality.
Solution Approach 2:
The PTC ink serves itself by automatically regulating its own heating through its inherent positive temperature coefficient property. As the ink heats up, its resistance increases naturally, reducing current flow and preventing overheating without requiring external control electronics or feedback circuits.
2Area of stationary object
If heating elements and bus bars are printed on the same side of the substrate, then manufacturing is simplified, but heating surface area is reduced due to space occupation by bus bars
Solution Approach 1:
The patent transitions from single-sided to double-sided printing by utilizing the third dimension (depth/thickness) of the flexible substrate. Heating elements are printed on one side while bus bars are printed on the opposite side, allowing both components to occupy the same planar footprint without interfering with each other's functional area.
Solution Approach 2:
The patent segments the electrical circuit functions into separate layers: the heating element layer and the bus bar layer. This spatial segmentation allows each component to be optimized for its specific function without competing for surface space, while still being electrically connected through the substrate thickness.
3Weight of moving object
If copper circuitry is used for heating elements, then electrical conductivity is high, but material cost and device weight increase
Solution Approach 1:
The patent changes the material parameter from traditional copper conductors to PTC ink formulation. The ink contains conductive particles suspended in a polymer matrix, providing sufficient electrical conductivity for heating applications while dramatically reducing material density and cost compared to solid copper traces.
Solution Approach 2:
The PTC heating element uses a composite material structure consisting of conductive particles (such as metal oxides or carbon) embedded in a polymer binder. This composite provides the necessary electrical conductivity for resistive heating while being significantly lighter and cheaper than pure copper circuitry.
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 enhances heating efficiency, reduces material costs, and allows for flexible and reliable heat distribution, enabling the creation of compact, efficient, and fault-tolerant heating devices suitable for various applications, including medical and mission-critical uses.
Implementation Method 1
The heating elements may be printed using a positive temperature coefficient (PTC) ink, which may provide a self-regulated maximum temperature based on a given input voltage.
Implementation Method 2
Resistive heating devices may include a power source connected to a resistive heating element, where the resistive heating element generates heat in response to applied power.
Data Source
AI summary
An improved resistive heating device includes multiple printed heating elements joined through a flexible film substrate to bus bars printed on an opposite side of the flexible film. The heating elements may be printed using a positive temperature coefficient ink to provide a self-regulated maximum temperature based on a given input voltage. This printing of electrical components on both sides of a flexible film, referred to herein as double-sided polymer circuitry (D/SPC®), provides various additional advantages over single-sided printing, such as an increased heat per unit surface area. This also provides a more concentrated and evenly distributed heat pattern, and will reduce or eliminate the exhibition of hot spots or varying patterns of heat throughout the heating element. This printing on both sides of the flexible film results in an improved, fault-tolerant bus bar topology, which may be used in fault-critical medical applications or other mission-critical applications.