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PERSPECTIVE ARTICLES

3D bioprinting processes: A perspective on classification

and terminology

Jia Min Lee, Swee Leong Sing, Miaomiao Zhou, Wai Yee Yeong *
Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological University,
Singapore

Abstract: This article aims to provide further classification of cell-compatible bioprinting processes and examine the
concept of 3D bioprinting within the general technology field of 3D printing. These technologies are categorized into four
distinct process categories, namely material jetting, vat photopolymerization, material extrusion and free-form spatial
printing. Discussion will be presented on the definition of classification with example of techniques grouped under the same
category. The objective of this article is to establish a basic framework for standardization of process terminology in order to
accelerate the implementation of bioprinting technologies in research and commercial landscape.
Keywords: additive manufacturing; 3D bioprinting; material jetting; material extrusion; vat photopolymerization;
bioassembly
*Correspondence to: Wai Yee Yeong, Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological
University, N3.1-B2C-03, 50 Nanyang Avenue, Singapore 639798; wyyeong@ntu.edu.sg

Received: June 1, 2018; Accepted: June 25, 2018; Published Online: July 3, 2018
Citation: Lee J M, Sing S L, Zhou M, et al., 2018, 3D bioprinting processes: A perspective on classification and
terminology. Int J Bioprint, 4(2): 151. http://dx.doi.org/10.18063/IJB.v4i2.151

[2]
1. Introduction racterization of the processes . Several reviews have
also highlighted current bioprinting technologies and
Biofabrication, bioprinting, and bioassembly are three compared the print resolution between the different
terms that have received great attention in recent technologies [2–5] . These published articles have
years [1,2] . The definition of biofabrication has been provided the necessary basic clarity on the definition of
highlighted as “the automated generation of biologically biofabrication. However, much work is still needed to
functional products with structural organization from further categorize the 3D bioprinting process in terms of
living cells, bioactive molecules, biomaterials, cell processes and terminology.
aggregates such as microtissues, hybrid cell-material The field of 3D bioprinting started from the idea of
[1]
constructs through bioprinting or bioassembly” . combining additive manufacturing (AM) or 3D printing
Defining terminologies and technologies in the field of which uses layer-by-layer fabrication techniques with
biofabrication is much needed to establish a framework living organisms and biomaterials to produce complex
and provide a reference map to the research community. tissues in vitro . While there is much advancement
[6]
Recently, researchers proposed a refined working in this field, the academia and industry have seen a
definition of Biofabrication, including Bioprinting lower adaptation rate of 3D bioprinting compared to
and Bioassembly as complementary stra tegies within AM due to the lack of clarity in processes, materials
Biofabrication. While Moroni et al. established a and applications. There exist some form of mismatch
guide for terminology in biofabrication and defined the between these three.
efficiency of the respective biofabrication technologies This article aims to provide a classification of 3D
using a metric system called spatial resolution/time bio printing processes that have been reviewed and
for manufacturing (RTM) ratio as a quantitative cha- described in detail in numerous reviews [3,7,8] . The details

3D bioprinting processes: A perspective on classification and terminology. © 2018 Lee J M, et al. This is an Open Access article distributed under the terms
of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-
commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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