US-20260129719-A1 - Strain-Insensitive Heating Element, Strain-Insensitive Heating Element Manufacturing Method, and Wearable Heating Device

US20260129719A1US 20260129719 A1US20260129719 A1US 20260129719A1US-20260129719-A1

Abstract

A strain-insensitive heater, a method for manufacturing the strain-insensitive heater, and a wearable heating device including the same are disclosed. The strain-insensitive heater includes a substrate; a heating portion formed on the substrate; a first electrode formed on the substrate and contacting the heating portion; and a second electrode formed on the substrate and contacting the heating portion, wherein the second electrode is spaced apart from the first electrode, wherein the heating portion includes an array of vertically aligned carbon nanotubes (VACNTs) arranged horizontally on the substrate, wherein a longitudinal axis of each of the VACNTs is oriented in a perpendicular manner to a surface of the substrate.

Inventors

Jong Baeg Kim
Sang Jun Sim
Kyu Bin BAE

Assignees

UIF (UNIVERSITY INDUSTRY FOUNDATION), YONSEI UNIVERSITY

Dates

Publication Date: 20260507
Application Date: 20241121
Priority Date: 20231128

Claims (16)

1 . A strain-insensitive heater comprising: a substrate; a heating portion formed on the substrate; a first electrode formed on the substrate and contacting the heating portion; and a second electrode formed on the substrate and contacting the heating portion, wherein the second electrode is spaced apart from the first electrode, wherein the heating portion includes an array of vertically aligned carbon nanotubes (VACNTs) arranged horizontally on the substrate, wherein a longitudinal axis of each of the VACNTs is oriented in a perpendicular manner to a surface of the substrate.
2 . The strain-insensitive heater of claim 1 , wherein the substrate is a flexible substrate.
3 . The strain-insensitive heater of claim 1 , wherein each of the first electrode and the second electrode includes a flexible conductive material.
4 . The strain-insensitive heater of claim 3 , wherein the first electrode or the second electrode includes a liquid metal.
5 . The strain-insensitive heater of claim 3 , wherein the first electrode and the second electrode are covered with a passivation layer including a polymer.
6 . The strain-insensitive heater of claim 1 , wherein when the heating portion has been stretched at a strain of 350% in the horizontal direction of the substrate, the strain-insensitive heater maintains 95% to 105% of heating performance thereof in a non-stretched state of the heating portion.
7 . The strain-insensitive heater of claim 1 , wherein when stretching of the heating portion at a strain of 200% in the horizontal direction of the substrate has been repeated 10,000 times, the strain-insensitive heater maintains 95% to 105% of heating performance thereof before the repetition of the stretching.
8 . The strain-insensitive heater of claim 2 , wherein the flexible substrate is a wrinkled flexible substrate.
9 . A method for manufacturing a strain-insensitive heater, the method comprising: providing a substrate; forming a first electrode and a second electrode on the substrate such that the first electrode and the second electrode are spaced apart from each other; and forming a heating portion on the substrate so as to contact the first electrode and the second electrode, wherein forming the heating portion includes transferring an array of vertically aligned carbon nanotubes (VACNTs) onto the substrate such that the vertically aligned carbon nanotubes (VACNTs) are arranged horizontally on the substrate, wherein a longitudinal axis of each of the VACNTs is oriented in a perpendicular manner to a surface of the substrate.
10 . The method for manufacturing the strain-insensitive heater of claim 9 , wherein the substrate is a flexible substrate.
11 . The method for manufacturing the strain-insensitive heater of claim 9 , wherein each of the first electrode and the second electrode includes a flexible conductive material.
12 . The method for manufacturing the strain-insensitive heater of claim 11 , wherein the first electrode or the second electrode includes a liquid metal.
13 . The method for manufacturing the strain-insensitive heater of claim 9 , wherein the method for manufacturing the strain-insensitive heater further comprises forming a passivation layer on the first electrode and the second electrode, wherein the passivation layer includes a polymer.
14 . The method for manufacturing the strain-insensitive heater of claim 9 , wherein transferring the array of the vertically aligned carbon nanotubes (VACNTs) includes: applying an uncured polymer as an adhesive layer onto the substrate; and transferring the array of the vertically aligned carbon nanotubes onto the adhesive layer.
15 . The method for manufacturing the strain-insensitive heater of claim 10 , wherein the flexible substrate is a wrinkled flexible substrate.
16 . A wearable heating device comprising: the strain-insensitive heater of claim 1 ; and a power source for applying electrical power to the strain-insensitive heater.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Korean Patent Application No. 10-2023-0167836 filed on Nov. 28, 2023 in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. 119, the contents of which are herein incorporated by reference in its entirety. BACKGROUND Field The present disclosure relates to a strain-insensitive heater, a method for manufacturing the strain-insensitive heater, and a wearable heating device including the same. Description of Related Art Researchers are seeking various methods to improve stretchability of a stretchable heating portion while maintaining heating performance of the stretchable heating portion. For example, a liquid metal-based stretchable heating portion with a strain of 100% or greater includes a complex pattern and employs a Kirigami structure utilizing a polyimide sheet coated with silver nanowires. However, these existing methods have the disadvantage of requiring time-consuming processes such as direct printing or laser cutting. SUMMARY In contrast thereto, the present disclosure proposes a stretchable heating portion that may be manufactured using vertically aligned carbon nanotubes (VACNTs) and without a complex patterning process. This stretchable heating portion has the advantage of maintaining constant heating performance due to almost no change in resistance even under strain. Thus, a purpose of the present disclosure is to provide a flexible and durable heater suitable for a wearable device. To this end, a heating portion using vertically aligned carbon nanotubes (VACNTs), a flexible substrate, an electrode using a flexible conductive material, and a passivation layer including a polymer are used. Through this innovative configuration, the heater of the present disclosure maintains consistent heating performance even under strain and repeated use, and overcomes the limitations in terms of flexibility and durability of the existing heaters. The high conductivity and mechanical flexibility of the VACNTs improve the efficiency and stretchability of the heater, and the flexible substrate and the electrode made of the flexible and conductive material enhance durability of the heater. The polymer passivation layer protects the electrode and enhances stability of the heater. As a result, the strain-insensitive heater of the present disclosure may be applied to various wearable devices such as medical heating patches, sportswear, wearable refrigerators, and wearable heating devices, and may increase a possibility of commercialization of wearable technology. Purposes according to the present disclosure are not limited to the above-mentioned purpose. Other purposes and advantages according to the present disclosure that are not mentioned may be understood based on following descriptions, and may be more clearly understood based on embodiments according to the present disclosure. Further, it will be easily understood that the purposes and advantages according to the present disclosure may be realized using means shown in the claims or combinations thereof. A first aspect of the present disclosure provides a strain-insensitive heater comprising: a substrate; a heating portion formed on the substrate; a first electrode formed on the substrate and contacting the heating portion; and a second electrode formed on the substrate and contacting the heating portion, wherein the second electrode is spaced apart from the first electrode, wherein the heating portion includes an array of vertically aligned carbon nanotubes (VACNTs) arranged horizontally on the substrate, wherein a longitudinal axis of each of the VACNTs is oriented in a perpendicular manner to a surface of the substrate. In accordance with some embodiments of the strain-insensitive heater, the substrate is a flexible substrate. In accordance with some embodiments of the strain-insensitive heater, each of the first electrode and the second electrode includes a flexible conductive material. In accordance with some embodiments of the strain-insensitive heater, the first electrode or the second electrode includes a liquid metal. In accordance with some embodiments of the strain-insensitive heater, the first electrode and the second electrode are covered with a passivation layer including a polymer. In accordance with some embodiments of the strain-insensitive heater, when the heating portion has been stretched at a strain of 350% in the horizontal direction of the substrate, the strain-insensitive heater maintains 95% to 105% of heating performance thereof in a non-stretched state of the heating portion. In accordance with some embodiments of the strain-insensitive heater, when stretching of the heating portion at a strain of 200% in the horizontal direction of the substrate has been repeated 10,000 times, the strain-insensitive heater maintains 95% to 105% of heating performance thereof before the repetition of the stretching. In accordance with