Page 160 - IJB-10-5

International

Journal of Bioprinting

RESEARCH ARTICLE
Experimental and numerical approaches

for optimizing conjunction area design to
enhance switching efficiency in single-nozzle

multi-ink bioprinting systems

Mitsuyuki Hidaka, Masaru Kojima , Colin Zhang , Yasunori Okano ,
id
id
id
and Shinji Sakai* id
Department of Materials Engineering Science, Osaka University, Osaka, Japan

Abstract

Three-dimensional (3D) bioprinting has emerged as a promising technology in
the field of tissue engineering. Notably, the advancement of multi-ink printing
technology is crucial for further progress in 3D bioprinting. In this study, we
developed a single-nozzle system with multiple inlets for multi-ink bioprinting
that achieves high switching efficiency through a combination of numerical and
experimental approaches. This single-nozzle system demonstrates the potential
for higher-resolution printing and quicker ink switching compared with multi-
nozzle printing systems. In general, inks used in bioprinting have low viscosity (<10
Pa·s); however, their behaviors inside a single nozzle have not been thoroughly
investigated. Initially, we conducted numerical simulations to analyze fluid behavior
*Corresponding authors: within single nozzles, focusing on the junction of multiple ink inlets, to propose an
Shinji Sakai
(sakai@cheng.es.osaka-u.ac.jp) advanced nozzle design. We proposed a novel index called switching efficiency (Se)
for evaluating the switching behavior of the bioink inside the single nozzle. Numerical
Citation: Hidaka M, Kojima M,
Zhang C, Okano Y, Sakai S. simulation results showed that the nozzle design and combinations of inks affected
Experimental and numerical Se. In addition, subsequent experimental analysis confirmed the consistency of the
approaches for optimizing simulation results. The proposed design, developed using simulations, featured a
conjunction area design to enhance
switching efficiency in single-nozzle single nozzle with enhanced switching efficiency, demonstrating a smaller transition
multi-ink bioprinting systems. length compared with that of conventional single nozzles or T-junction nozzles in
Int J Bioprint. 2024;10(5):4091. printing line structures of different viscous inks. This is the first study to employ
doi: 10.36922/ijb.4091
numerical simulation in designing a single nozzle with multiple inlets to switch ink in
Received: June 30, 2024 multi-ink bioprinting. This methodology will broaden the potential of single nozzles
Revised: July 26, 2024 for high-resolution printing in bioprinting applications.
Accepted: August 6, 2024
Published Online: August 8, 2024
Copyright: © 2024 Author(s). Keywords: 3D bioprinting; Multi-ink printing; Single-nozzle printing; Numerical
This is an Open Access article simulation
distributed under the terms of the
Creative Commons Attribution
License, permitting distribution,
and reproduction in any medium,
provided the original work is
properly cited. 1. Introduction
Publisher’s Note: AccScience Three-dimensional (3D) printing is a manufacturing technology that automatically
Publishing remains neutral with assembles materials in 3D patterns. This technology builds materials layer by layer,
regard to jurisdictional claims in enabling the construction of complex structures at reduced costs and time. The recent
1,2
published maps and institutional
affiliations. trend sees the adoption of 3D printing in tissue engineering, where inks containing cells

Volume 10 Issue 5 (2024) 152 doi: 10.36922/ijb.4091