Highly Flexible, Self-Bonding, Self-Healing, and Conductive Soft Pressure Sensors Based on Dicarboxylic Cellulose Nanofiber Hydrogels

Ragab Abouzeid; Mohammad Shayan; Tongyao Wu; Jaegyoung Gwon; Timo A Kärki; Qinglin Wu

doi:10.1021/acsapm.3c01024

Highly Flexible, Self-Bonding, Self-Healing, and Conductive Soft Pressure Sensors Based on Dicarboxylic Cellulose Nanofiber Hydrogels

ACS Appl Polym Mater. 2023 Aug 8;5(9):7009-7021. doi: 10.1021/acsapm.3c01024. eCollection 2023 Sep 8.

Authors

Ragab Abouzeid^{1

2}, Mohammad Shayan¹, Tongyao Wu³, Jaegyoung Gwon⁴, Timo A Kärki⁵, Qinglin Wu¹

Affiliations

¹ School of Renewable Natural Resources, Louisiana State University, AgCenter, Baton Rouge, Louisiana 70803, United States.
² Cellulose and Paper Department, National Research Centre, 33 Bohouth St., Dokki, Giza 12622, Egypt.
³ Department of Electrical and Computer Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
⁴ Forest Products Department, National Institute of Forest Science, 57 Hoegiro, Dongdaemun-gu, Seoul 02455, Korea.
⁵ Mechanical Engineering Department, Lappeenranta-Lahti University of Technology, Lappeenranta53850 ,Finland.

Abstract

Conductive hydrogels have gained a great deal of interest in the flexible electronics industry because of their remarkable inherent properties. However, a significant challenge remains for balancing hydrogel's conductivity, self-healing, and strength properties. Herein, double network ionic hydrogels were fabricated by concurrently introducing borax into dicarboxylic cellulose nanofiber (DCNFs) and polyacrylamide (PAM) hydrogels. The incorporation of borax provided a superabsorbent feature to the PAM/DCNF hydrogels (without borax) with the equilibrium water absorption rate increased from 552 to 1800% after 42 h. The compressive strength of the prepared hydrogel was 935 kPa compared to 132 kPa for the PAM hydrogel, with high cycling stability (stable after 1000 compression cycles with 50% strain). The hydrogel pressure sensor had a very sensitive response (gauge factor = 1.36) in the strain range from 10 to 80%, which made it possible to detect mechanical motion accurately and reliably. The developed hydrogels with high-performance, environmentally friendly properties are promising for use in future artificial skin and human-machine interface applications.