3D-Printed Microstructured Ionic Hydrogels for Enhanced Electric Double-Layer Pressure Sensing

Abstract

Hydrogel-based pressure sensors have attracted increasing attention for wearable sensing applications due to their intrinsic softness, flexibility, biocompatibility, and permeability. However, the influence of surface microstructure geometry on the electromechanical response of hydrogels remains insufficiently understood, and scalable fabrication strategies for engineering such structures are limited. In this study, we investigate the effect of surface microstructure geometry on the pressure-sensing performance of ionic hydrogel sensors fabricated using a low-cost digital light processing (DLP) 3D printing. A chitosan/poly(ethylene glycol) diacrylate hydrogel was assembled and printed with different microstructures by integrating surface protrusion array configurations. The pressure-sensing behavior was characterized using capacitive measurements. The results showed that microstructured hydrogels exhibit enhanced pressure sensitivity compared to solid hydrogels due to deformation-induced changes in the electric double-layer (EDL) capacitance at the hydrogel-electrode interface. The hydrogel with more densely distributed protrusions (17x17) demonstrated the highest-pressure sensitivity of 0.42 kPa-1, compared to 0.082 kPa-1 for the solid hydrogel. Furthermore, increasing ionic concentration by incorporating LiCl significantly improved sensitivity to 1.46 kPa-1. Wireless sensing experiments confirmed that pressure-dependent resonant frequency shifts, with the 17x17 structure exhibiting higher sensitivity than the 7x7 structure. These results demonstrate that engineering hydrogel surface microstructures provides a strategy to enhance the performance of soft pressure sensors for wearable and wireless sensing applications.

Department(s)

Mechanical and Aerospace Engineering

Comments

Missouri University of Science and Technology, Grant None

Keywords and Phrases

additive manufacturing; electrical double-layer capacitance; Hydrogel sensor; ionic hydrogels; wearable sensor; wireless passive sensing

International Standard Book Number (ISBN)

978-151069837-6

International Standard Serial Number (ISSN)

1996-756X; 0277-786X

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2026 Society of Photo-Optical Instrumentation Engineers, All rights reserved.

Publication Date

16 Apr 2026

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