Non-contact humidity monitoring: Boosting the performance of all-printed humidity sensor using PDDA-modified Ti3C2Tx nanoribbons

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 485; p. 149633
• Main Authors: Huang, Meng-lin, Lu, Jie, Ji, Jing-xin, Zhang, Hao-wen, Xu, Zhao-quan, Feng, Zhe-sheng, Wu, Wei, Wang, Yan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2024
• Subjects: Flexible sensor; MXene; Non-contact humidity monitoring; Screen printing; Screen printing; Flexible sensor; Non-contact humidity monitoring; MXene
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.149633

A novel composite material (PDDA-modified Ti3C2Tx nanoribbons) was created to fabricate flexible humidity sensors through a fully printed method, demonstrating excellent practicality in multiple application scenarios including non-contact humidity monitoring. [Display omitted] •The 3D porous structure was formed by alkalizing Ti3C2Tx MXene.•The KPMX composite was made by adding PDDA chains to Ti3C2Tx nanoribbons.•The flexible humidity sensor was fully printed and suitable for mass production.•The new sensor showed excellent humidity monitoring performance with good stability. Non-contact humidity monitoring can provide us with rich information about our bodies in a non-invasive way. However, this concept is hindered by the low sensitivity and slow response time of conventional humidity sensors. Herein, we employed two strategies, structural design and surface modification of MXene materials, to improve the sensitivity of MXene-based humidity sensors. A 3D porous structure was formed by the alkalinization treatment MXene, which facilitated rapid diffusion of water molecules along interlayer nanochannels and fast electron transport. Furthermore, the charged positively poly (diallyldimethylammonium chloride) (PDDA) was adsorbed onto the surface of the 3D skeleton through self-assembly to prepare a novel composite material KPMX. The loaded PDDA enhanced the interaction between MXene and water molecules, reducing the oxidation sensitivity of MXene. Additionally, the material was further formulated as inks with suitable viscosity and successfully used to produce a paper-based flexible humidity sensor through screen printing. Consequently, the KPMX sensor exhibited impressive potential in humidity sensing with high sensitivity (48813 %), rapid response/recovery time (8.794/2.656 s), and excellent stability. This work provided a practical strategy for non-contact humidity monitoring, including detecting the proximity of fingertips and changes in humidity in breathing patterns.