A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes

A fully inkjet-printed strain sensor based on carbon nanotubes (CNTs) was fabricated in this study for microstrain and microcrack detection. Carbon nanotubes and silver films were used as the sensing layer and conductive layer, respectively. Inkjet-printed CNTs easily undergo agglomeration due to va...

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Main Authors: Hsuan-Ling Kao, Cheng-Lin Cho, Li-Chun Chang, Chun-Bing Chen, Wen-Hung Chung, Yun-Chen Tsai
Format: Article
Language:English
Published: MDPI AG 2020-08-01
Series:Coatings
Subjects:
Online Access:https://www.mdpi.com/2079-6412/10/8/792
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spelling doaj-b61bfd5e2e344d38a34b80a448dae1362020-11-25T03:31:09ZengMDPI AGCoatings2079-64122020-08-011079279210.3390/coatings10080792A Fully Inkjet-Printed Strain Sensor Based on Carbon NanotubesHsuan-Ling Kao0Cheng-Lin Cho1Li-Chun Chang2Chun-Bing Chen3Wen-Hung Chung4Yun-Chen Tsai5Department of Electronic Engineering, Chang Gung University, Tao-Yuan 33302, TaiwanDepartment of Electronic Engineering, Chang Gung University, Tao-Yuan 33302, TaiwanDepartment of Materials Engineering, Ming Chi University of Technology, New Taipei 243303, TaiwanDepartment of Dermatology, Chang Gung Memorial Hospital, Keelung, Taipei, and Linkou Branches, Tao-Yuan 33305, TaiwanDepartment of Dermatology, Chang Gung Memorial Hospital, Keelung, Taipei, and Linkou Branches, Tao-Yuan 33305, TaiwanDepartment of Electronic Engineering, Chang Gung University, Tao-Yuan 33302, TaiwanA fully inkjet-printed strain sensor based on carbon nanotubes (CNTs) was fabricated in this study for microstrain and microcrack detection. Carbon nanotubes and silver films were used as the sensing layer and conductive layer, respectively. Inkjet-printed CNTs easily undergo agglomeration due to van der Waals forces between CNTs, resulting in uneven films. The uniformity of CNT film affects the electrical and mechanical properties. Multi-pass printing and pattern rotation provided precise quantities of sensing materials, enabling the realization of uniform CNT films and stable resistance. Three strain sensors printed eight-layer CNT film by unidirectional printing, rotated by 180° and 90° were compared. The low density on one side of eight-layer CNT film by unidirectional printing results in more disconnection and poor connectivity with the silver film, thereby, significantly increasing the resistance. For 180° rotation eight-layer strain sensors, lower sensitivity and smaller measured range were found because strain was applied to the uneven CNT film resulting in non-uniform strain distribution. Lower resistance and better strain sensitivity was obtained for eight-layer strain sensor with 90° rotation because of uniform film. Given the uniform surface morphology and saturated sheet resistance of the 20-layer CNT film, the strain performance of the 20-layer CNT strain sensor was also examined. Excluding the permanent destruction of the first strain, 0.76% and 1.05% responses were obtained for the 8- and 20-layer strain sensors under strain between 0% and 3128 µε, respectively, which demonstrates the high reproducibility and recoverability of the sensor. The gauge factor (GF) of 20-layer strain sensor was found to be 2.77 under strain from 71 to 3128 µε, which is higher than eight-layer strain sensor (GF = 1.93) due to the uniform surface morphology and stable resistance. The strain sensors exhibited a highly linear and reversible behavior under strain of 71 to 3128 µε, so that the microstrain level could be clearly distinguished. The technology of the fully inkjet-printed CNT-based microstrain sensor provides high reproducibility, stability, and rapid hardness detection.https://www.mdpi.com/2079-6412/10/8/792inkjet printingcarbon nanotubesstrain sensors
collection DOAJ
language English
format Article
sources DOAJ
author Hsuan-Ling Kao
Cheng-Lin Cho
Li-Chun Chang
Chun-Bing Chen
Wen-Hung Chung
Yun-Chen Tsai
spellingShingle Hsuan-Ling Kao
Cheng-Lin Cho
Li-Chun Chang
Chun-Bing Chen
Wen-Hung Chung
Yun-Chen Tsai
A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes
Coatings
inkjet printing
carbon nanotubes
strain sensors
author_facet Hsuan-Ling Kao
Cheng-Lin Cho
Li-Chun Chang
Chun-Bing Chen
Wen-Hung Chung
Yun-Chen Tsai
author_sort Hsuan-Ling Kao
title A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes
title_short A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes
title_full A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes
title_fullStr A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes
title_full_unstemmed A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes
title_sort fully inkjet-printed strain sensor based on carbon nanotubes
publisher MDPI AG
series Coatings
issn 2079-6412
publishDate 2020-08-01
description A fully inkjet-printed strain sensor based on carbon nanotubes (CNTs) was fabricated in this study for microstrain and microcrack detection. Carbon nanotubes and silver films were used as the sensing layer and conductive layer, respectively. Inkjet-printed CNTs easily undergo agglomeration due to van der Waals forces between CNTs, resulting in uneven films. The uniformity of CNT film affects the electrical and mechanical properties. Multi-pass printing and pattern rotation provided precise quantities of sensing materials, enabling the realization of uniform CNT films and stable resistance. Three strain sensors printed eight-layer CNT film by unidirectional printing, rotated by 180° and 90° were compared. The low density on one side of eight-layer CNT film by unidirectional printing results in more disconnection and poor connectivity with the silver film, thereby, significantly increasing the resistance. For 180° rotation eight-layer strain sensors, lower sensitivity and smaller measured range were found because strain was applied to the uneven CNT film resulting in non-uniform strain distribution. Lower resistance and better strain sensitivity was obtained for eight-layer strain sensor with 90° rotation because of uniform film. Given the uniform surface morphology and saturated sheet resistance of the 20-layer CNT film, the strain performance of the 20-layer CNT strain sensor was also examined. Excluding the permanent destruction of the first strain, 0.76% and 1.05% responses were obtained for the 8- and 20-layer strain sensors under strain between 0% and 3128 µε, respectively, which demonstrates the high reproducibility and recoverability of the sensor. The gauge factor (GF) of 20-layer strain sensor was found to be 2.77 under strain from 71 to 3128 µε, which is higher than eight-layer strain sensor (GF = 1.93) due to the uniform surface morphology and stable resistance. The strain sensors exhibited a highly linear and reversible behavior under strain of 71 to 3128 µε, so that the microstrain level could be clearly distinguished. The technology of the fully inkjet-printed CNT-based microstrain sensor provides high reproducibility, stability, and rapid hardness detection.
topic inkjet printing
carbon nanotubes
strain sensors
url https://www.mdpi.com/2079-6412/10/8/792
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