Predictive Modeling of Droplet Formation Processes in Inkjet-Based Bioprinting

Abstract

Additive manufacturing is driving major innovations in many areas such as biomedical engineering. Recent advances have enabled three-dimensional (3D) printing of biocompatible materials and cells into complex 3D functional living tissues and organs using bio-printable materials (i.e., bioink). Inkjet-based bioprinting fabricates the tissue and organ constructs by ejecting droplets onto a substrate. Compared with microextrusion-based and laser-assisted bioprinting, it is very difficult to predict and control the droplet formation process (e.g., droplet velocity and volume). To address this issue, this paper presents a new data-driven approach to predicting droplet velocity and volume in the inkjet-based bioprinting process. An imaging system was used to monitor the droplet formation process. To investigate the effects of polymer concentration, excitation voltage, dwell time, and rise time on droplet velocity and volume, a full factorial design of experiments (DOE) was conducted. Two predictive models were developed to predict droplet velocity and volume using ensemble learning. The accuracy of the two predictive models was measured using the root-mean-square error (RMSE), relative error (RE), and coefficient of determination (R2). Experimental results have shown that the predictive models are capable of predicting droplet velocity and volume with sufficient accuracy.

Biofabrication of three-dimensional cellular structures based on gelatin methacrylate–alginate interpenetrating network hydrogel

“…Fortunately, organ printing and tissue regeneration, among various other tissue engineering innovations, has emerged as a very promising solution to solve this problem, which utilizes cellular spheroids or bioink as building blocks for the fabrication of three-dimensional (3D) functional tissues and organs using a layer-by-layer manufacturing mechanism. 2–4 The fabricated tissues and organs are expected to be suitable for regeneration, repair and replacement of damaged or injured tissues and organs in the human body. The main 3D bioprinting technologies implemented include inkjet printing, 5–8 microextrusion, 9–11 and laser-assisted printing.…”

Effects of Encapsulated Cells on the Physical–Mechanical Properties and Microstructure of Gelatin Methacrylate Hydrogels

“…The encapsulation of living cells inside biomaterials is an approach in tissue engineering that allows for the engineering of living tissues with structural and biochemical similarities to natural tissue [1]. Hydrogels are widely used due to important properties such as a high water content, biocompatibility, and their ability to mimic the microstructure of a cell’s natural extracellular matrix (ECM) [2,3]. Hydrogel physical–mechanical properties and microstructures are of great importance to cell attachment, viability, differentiation, and proliferation as well as the eventual functionality of the fabricated tissues.…”

Bioprinting: A Strategy to Build Informative Models of Exposure and Disease

“…DOD inkjet is preferred because it generates droplets when required, unlike CI due to the Rayleigh-Plateau physical phenomenon [44], [45]. Methods based on machine learning have been developed to study droplet properties such as droplet size and volume to improve deposition precision and stability [46]- [48]. DOD inkjet ejects drops of bioink onto a suitable substrate by overcoming steady and unsteady inertia.…”