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Fabrication of bulk alumina structures with humidity sensing capabilities using direct ink write technique

Anabel Renteria (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)
Luisa F. Garcia (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)
Jorge A. Diaz (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)
Luis C. Delfin (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)
Jaime E. Regis (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)
Elizabeth I. Reza (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)
David Espalin (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)
Tzu-Liang Bill Tseng (Department of Industrial, Manufacturing and Systems Engineering, University of Texas at El Paso, El Paso, Texas, USA)
Yirong Lin (Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas, USA)

Rapid Prototyping Journal

ISSN: 1355-2546

Article publication date: 18 May 2021

Issue publication date: 4 June 2021

150

Abstract

Purpose

The purpose of this study is to evaluate different 3D structures for humidity sensing that will enable the fabrication of complex geometries with high moisture sensitivity.

Design/methodology/approach

Humidity sensors based on alumina ceramics were fabricated using direct ink write (DIW) technique. Different engineered surface area, polymer binder ratio and post-processing treatment were considered to increase moisture sensitivity.

Findings

It was found that the binder ratio plays an important role in controlling the rheology of the paste during printing and determining the pore size after post-processing treatment. The sensibility of the fabricated humidity sensor was investigated by measuring its capacitance response toward relative humidity (RH) varying from 40% to 90% RH at 25°C. It is shown that using 3D lattice design, printed alumina humidity sensor could improve sensitivity up to 31.6 pF/RH%, over an order of magnitude higher than solid alumina.

Originality/value

Most of the alumina humidity sensors available are films in nature because of manufacturing difficulties, which limited its potential of higher sensitivity, and thus broader applications. In this paper, a novel 3D alumina humidity sensor was fabricated using DIW 3D printing technology.

Keywords

Acknowledgements

This research is funded by Department of Energy (DOE) under Grant Nos DE-FE0027502 and DE-NA0003865.

Citation

Renteria, A., Garcia, L.F., Diaz, J.A., Delfin, L.C., Regis, J.E., Reza, E.I., Espalin, D., Tseng, T.-L.B. and Lin, Y. (2021), "Fabrication of bulk alumina structures with humidity sensing capabilities using direct ink write technique", Rapid Prototyping Journal, Vol. 27 No. 4, pp. 822-833. https://doi.org/10.1108/RPJ-12-2019-0322

Publisher

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Emerald Publishing Limited

Copyright © 2021, Emerald Publishing Limited

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