Carbon Nanotube Joule Heating Elements Low Voltage Operation
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Solution Overview
Problem
Existing joule heating devices rely on high voltage potentials, which are not always available, especially in applications like battery-powered electronics and textiles, where efficient heating at lower voltages is needed.
Innovation Solution
Development of conformable, flexible, low mass carbon nanotube-based joule heating elements, including aligned thin film, dispersed composite, and stitched carbon nanotube forms, which can operate effectively under 25 V, leveraging the high electrical and thermal conductivity of carbon nanotubes for efficient heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metal alloy heaters like Kanthal, Nichrome, and Cupronickel are used, then high temperature resistance without oxidation is achieved, but higher voltage operation is required which is not available in portable devices
Solution Approach 1:
The patent changes the material parameters by using carbon nanotubes with specific electrical conductivity (10^3 to 10^5 S/cm) and resistivity (10^-6 to 10^-4 ohm-cm) to enable operation at lower voltages (1-24V) while maintaining high temperature resistance up to 400°C. This parameter change in material properties resolves the contradiction between temperature resistance and voltage requirement.
Solution Approach 2:
The patent employs composite material structures including carbon nanotube-polymer composites and carbon nanotube-ceramic composites. These composites combine the high temperature stability of carbon nanotubes with the electrical conductivity needed for low-voltage operation, resolving the contradiction between temperature resistance and voltage requirement.
2Power
If traditional metal-based resistive heaters are used, then sufficient heating capability is achieved, but they are not suitable for battery-powered electronics and textiles due to high voltage requirements
Solution Approach 1:
The patent changes the electrical parameters of the heating element by using carbon nanotubes with tunable resistivity (10^-6 to 10^-4 ohm-cm) to optimize power delivery at low voltages (1-24V), enabling battery-powered operation while maintaining heating capability. This expands the application range to portable electronics and textiles.
Solution Approach 2:
The patent uses flexible carbon nanotube thin films and conformable composite structures that can be integrated into textiles and wearable devices. This structural adaptation expands the application range from traditional rigid heaters to flexible applications in clothing and portable electronics.
3Use of energy by moving object
If carbon nanotube-based heating elements are used, then low voltage operation and low mass are achieved, but manufacturing complexity increases with multiple forms (aligned, dispersed, stitched)
Solution Approach 1:
The patent segments the carbon nanotube heating element manufacturing into three distinct approaches: aligned thin film structures, dispersed composite formulations, and stitched textile integrations. Each segment addresses different application needs while maintaining low-voltage operation, managing manufacturing complexity through modular design.
Solution Approach 2:
The patent creates universal carbon nanotube-based heating elements that can be manufactured in multiple forms (aligned, dispersed, stitched) to serve different applications. The core carbon nanotube material provides universal low-voltage operation and low mass properties across all forms, while the manufacturing method adapts to specific application requirements.
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
These carbon nanotube-based heating elements provide efficient, rapid, and precise heating with low mass, suitable for applications in portable electronics, smart clothing, aerospace, and medical uses, maintaining performance even under mechanical fatigue and varying temperatures.
Implementation Method 1
joule, also known as ohmic or resistive, heating elements
Data Source
AI summary
Disclosed are methods of making low voltage joule heating elements (10, 40, 50) from carbon nanotubes (CNT) (32). In an embodiment, the heating element (10) includes layers (12) of aligned thin film CNTs. In another embodiment, the heating element (40) includes CNTs (32) dispersed in a polymer (34) to form a CNT polymer composite (30). In another embodiment, the heating element (50) includes CNT thread (52) stitched to a fabric (54). Each embodiment further includes a pair of electrodes (20, 22, 42, 44, 56, 58) that are configured to be couple to a source of electricity. Embodiments further include an encapsulating film (24, 46) over at least the heating element. The heating elements (10, 40, 50) produced by the processes disclosed herein are lightweight and highly efficient and suitable for many uses including incorporation into objects such as clothing and footwear.