Printed Carbon Nanotubes-Based Flexible Resistive Humidity Sensor

• Published in: IEEE sensors journal Vol. 20; no. 21; pp. 12592 - 12601
• Main Authors: Zhang, Xingzhe, Maddipatla, Dinesh, Bose, Arnesh K., Hajian, Sajjad, Narakathu, Binu Baby, Williams, John D., Mitchell, Michael F., Atashbar, Massood Z.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-11-2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bend radius; Capacitive sensors; Gravure; gravure printing; heater; Heating systems; Humidity; hysteresis; Ink; Multi wall carbon nanotubes; multi-walled carbon nanotubes; Radius of curvature; Relative humidity; Resistive humidity sensor; screen printing; Sensor phenomena and characterization; Sensors; Substrates; Surface roughness
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2020.3002951

A resistive flexible humidity sensor based on multi-walled carbon nanotubes (MWCNTs) was designed and fabricated. Screen and gravure printing processes were used for monolithically fabricating the humidity sensor containing interdigitated electrodes (IDE), a sensing layer and a meandering conductive heater. An average thickness and surface roughness of <inline-formula> <tex-math notation="LaTeX">0.99~\mu \text{m} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">0.23~\mu \text{m} </tex-math></inline-formula>, respectively, was registered for the printed MWCNTs sensing layer. The capability of the printed sensor, with heater, was investigated by subjecting it to relative humidity (RH) ranging from 10% to 90%. The response demonstrated an overall resistance change of 55% when the sensor was subjected to 90% RH, when compared to 10% RH. A maximum hysteresis of 5.1%, at 70% RH, was calculated for the resistive response of the sensor. The printed sensors can be bend with radius of curvature of 1.5 inch with literally no effect.