Chemistry of Materials, Vol. 30, No. 21, pp. 7707-7713, October, 2018, DOI: 10.1021/acs.chemmater.8b03006

Flexible, Bio-Compatible Nanofluidic Ion Conductor

Chengwei Wang1, Sha Wang1, Guang Chen2, Weiqing Kong1, Weiwei Ping1, Jiaqi Dai1, Glenn Pastel1, Hua Xie1,Shuaiming He1, Siddhartha Das2,3, and Liangbing Hu1
1Department of Materials Science and Engineering, University of Maryland College Park,College Park, Maryland, 20742
2Department of Mechanical Engineering, University of Maryland College Park, College Park, Maryland, 20742
3CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20740, USA


Ion transport in nanochannels has unique behaviors such as charge selectivity and high ionic conductivity. Due to their simple structure, the photolithographic nanochannels have been widely used to understand the fundamentals of nanofluidic ion transport. However, for practical applications, especially bio-related applications, a scalable, flexible, mechanically stable, and biocompatible nanofluidic device engineered with charge selectivity and high ionic conductivity is more desirable. Herein, we report a scalable biomass material, namely bacterial cellulose (BC), with excellent mechanical strength, flexibility, and biocompatibility for nanofluidic ion transport. The BC film is a 3-dimensional (3D) interconnected network of 10-30 nm thick cellulose nanofibers, containing 1-2 nm nanochannels with large negatively charged surface groups. After a facile TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation treatment, the zeta potential of the cellulose nanofibers significantly improves from -13 mV to -45 mV, and the ionic conductivity increases 40 times from 2.5 × 10-5 S/cm to 1.0 × 10-3 S/cm at low salt concentrations. As a proof of concept, we successfully demonstrate an ultra-sensitive humidity sensor with the BC nanofluidic film for wearable health monitor applications.

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