Ligament flows of exit-pinching during drop-on-demand inkjetting of alginate solution

Mengyun Zhang, Changxue Xu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

Organ printing is an emerging technology for fabricating artificial tissues and organs, which are constructed layer by layer by precisely placing tissue spheroids or filaments as building blocks. These fabricated artificial organs offers a great potential as alternatives to replace the damaged human organs, providing a promising solution to solve organ donor shortage problem. Inkjetting, one of the key technologies in organ printing, has been widely developed for organ printing because of its moderate fabrication cost, good process controllability and scale-up potentials. Droplet formation process as the first step towards inkjetting 3D cellular structures needs to be studied and controlled precisely. This paper focuses on the ligament flow of exit-pinching during droplet formation process of inkjet printing. The ligament flow directions during pinch-off process of inkjet printing of a sodium alginate solution with a concentration of 0.5% (w/v) have been studied. It is found that two different types of flow directions inside a single ligament during pinch-off process may occur. At an excitation voltage of 30 V, the ligament flow has two different directions at the locations near the nozzle orifice and the jet front head: the negative z direction at the location near the nozzle orifice due to the dominant capillary effect, and the positive z direction at the location near the jet front head due to both the fluid inertial and capillary effects. On the contrary, at an excitation voltage of 70 V, the ligament flow directions are the same at the locations near the nozzle orifice and the jet front head: the positive z direction at the location near the nozzle orifice due to the sufficiently large fluid inertial effect, and the same positive z direction at the location near the jet front head due to both the fluid inertial and capillary effects. Two flow directions inside a single ligament benefit single droplet formation without satellite droplets, but the droplet trajectory will be easily affected by the airflow in the laboratory due to the small droplet velocity as well as the droplet deposition accuracy. Single flow direction inside a single ligament usually results in a long ligament due to the large fluid inertia which eventually breaks into several undesirable satellite droplets. The resulting knowledge will be beneficial for better understanding of the ligament pinch-off during droplet formation process of inkjet printing biological viscoelastic alginate bioink for 3D cellular structure fabrication as well as precise droplet controllability for good quality of fabricated 3D structures.

Original languageEnglish
Title of host publicationMaterials; Biomanufacturing; Properties, Applications and Systems; Sustainable Manufacturing
PublisherAmerican Society of Mechanical Engineers
ISBN (Electronic)9780791849903
DOIs
StatePublished - 2016
EventASME 2016 11th International Manufacturing Science and Engineering Conference, MSEC 2016 - Blacksburg, United States
Duration: Jun 27 2016Jul 1 2016

Publication series

NameASME 2016 11th International Manufacturing Science and Engineering Conference, MSEC 2016
Volume2

Conference

ConferenceASME 2016 11th International Manufacturing Science and Engineering Conference, MSEC 2016
CountryUnited States
CityBlacksburg
Period06/27/1607/1/16

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