The characterization of particle number and distribution inside in-flight 3D printed droplets using a high speed droplet imaging system

Abstract

3D bioprinting is an innovative and time-saving method to precisely generate cell-laden 3D structures for clinical and research applications. Ejected cell number and cell distribution are two key technical parameters for evaluation of the bioprinter performance. In this paper, a modified droplet imaging system is used to study cell-size fluorescent particle number and distribution within droplets ejected from a microvalve-based 3D bioprinter. The effects of droplet dispensing physics (dosing energy com.elsevier.xml.ani.Math@3286b7f), ink properties (Z number—the inverse of the Ohnesorge number and particle sedimentation velocity), and input particle concentration are considered. The droplet imaging system demonstrates a strong capability in analyzing bioprinting performance for seeded concentrations less than com.elsevier.xml.ani.Math@2e69ce4d particles/ml. The printed particle number increases near-linearly under increasing dosing energy and Z number. It was found that for com.elsevier.xml.ani.Math@582cec18 and seeded particle concentration no less than com.elsevier.xml.ani.Math@5d039f99 particles/ml, particles within the visualized droplets approached a homogeneous distribution in the 2D images. It was also determined that the particle sedimentation velocity within the ink has a positive relationship to the ejected particle number over time—with the particle distribution approaching a homogeneous state over increasing sedimentation time.