This document describes research on fabricating biological microspheres using inkjet printing and laser transfer methods. It finds that inkjet printing works well for low viscosity materials to form monodisperse, encapsulated microspheres, while laser transfer works for high viscosity materials. The size and distribution of the microspheres can be controlled by adjusting parameters like material concentration and laser fluence. Future work aims to better control microsphere size and uniformity for applications in drug delivery, tissue engineering, and stem cell studies.

1. Formation of Biological
Microspheres Using Ink
Jetting and Laser Transfer
Yong Huang
Associate Professor of Mechanical Engineering
Adjunct Associate Professor of Bioengineering
Clemson University, Clemson, SC 29634
http://www.ces.clemson.edu/camsil/
http://www.ces.clemson.edu/camsil/
Outline
 Background
 Fabrication Methods
 Results and Conclusions
 Summary and Future Collaborations
 Acknowledgements
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2. Introduction and Motivation
Encapsulated
materials (drug or cell)
Biomedical applications of microspheres:
 Controlled drug/cell delivery
 Cell encapsulation for transplantation
Matrix
 Cellular spheroid-based tissue engineering material
(polymer)
Microsphere
Challenges in microsphere fabrication
 Formability of size controllable microspheres using various low and high
viscosity biological materials
 Monodisperse distribution of fabricated microspheres
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Potential Fabrication Technologies
 Size controllability
 Good for low viscosity
materials
Ink jetting (thermal and
Nozzle jetting-based
piezoelectric)
Nozzleless Modified LIFT (Laser-Induced
jetting-based Forward Transfer)
 Clog free
 Good for viscous materials
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3. Outline
 Background
 Fabrication Methods
 Results and Conclusions
 Summary and Future Collaborations
 Acknowledgements
5
1. Vibration-Assisted Ink Jetting
Pressure pulse
For low viscosity materials Piezoelectric via piezoelectric
transducer device
Chamber
with liquid
solution
dN
Fluid reservoir
Orifice
dD
Microspheres Air gap
Nozzle Stir bar
Drop-on-demand
jetting schematic
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4. 2. Modified LIFT (Laser) For high viscosity materials
Mechanism Excimer UV laser
pulse (12 ns)
Objective
Focused UV
laser pulse
Transparent
Optional energy quartz support
conversion layer
System
Demagnified Cell/protein
setup UV laser pulse coating
Quartz support Laser pulse
Quartz
Adhesive
conversion
layer Flexible foil
Workpiece Direct-writing NaAlg suspension
Cells
Vacuum /substrate height Forming droplet
chuck
CaCl2 solution
Proposed metallic foil-assisted LIFT
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Outline
 Background
 Fabrication Methods
 Results and Conclusions
 Summary and Future Collaborations
 Acknowledgements
8

5. Vibration-Assisted Inkjet-Based Method
Good
100 µm
Formability
100 µm
Bad
100 µm
Sodium alginate concentration (%)
Microsphere formability as a function of sodium
alginate concentration (and other operating conditions)
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Vibration-Assisted Inkjet-Based Method
(cont’d)
Encapsulated
fluorescent beads
Microspheres
(alginate-based)
100 µm
Encapsulated monodisperse microsphere can be
formed as a function of sodium alginate concentration
and other operating conditions
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6. Laser-Based Method
A B C
Sodium alginate (NaAlg) concentration: (A) 2 %; (B) 4 %; (C) 6 %(w/v)
under laser fluence: 3858±34 mJ/cm2
Microsphere size Slightly
NaAlg
concentration
Size uniformity
Effect of NaAlg concentration 11
Laser-Based Method (cont’d)
A B
Microsphere
size
Laser
fluence Number of
satellite
C D droplets
Effect of laser fluence
Laser fluence: (A) 2030±29; (B) 3858±34; (C) 5734±43;
(D) 7436±48 mJ/cm² uisng 6 % (w/v) NaAlg solution
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7. Laser-Based Method (cont’d)
Using modified LIFT Using proposed metallic foil -
assisted LIFT
2 % (w/v) NaAlg solution with 1.8 ×106 beads/ml
Better encapsulation effect using proposed
metallic foil-assisted LIFT (laser-based)
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Outline
 Background
 Fabrication Methods
 Results and Conclusions
 Summary and Future Collaborations
 Acknowledgements
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8. Summary
 Encapsulated biological microspheres can be effectively fabricated
using proposed vibration-assisted ink jetting (for low viscosity
materials) and laser transfer (for high viscosity materials) based
approaches
 Future work - size control and size distribution control (monodispersity)
Future collaborations envisioned
 Encapsulated microspheres for controlled drug delivery
 Tissue microspheroids for cell transplantation and organ printing
 Encapsulated cellular microspheroids for controlled stem cell
differentiation study under matrix material-defined microenvironments
 More …
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Outline
 Background
 Fabrication Methods
 Results and Conclusions
 Summary and Future Collaborations
 Acknowledgements
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9. Acknowledgements
 Financial support: the National Textile Center, the
National Science Foundation (CMMI-CAREER and EPS),
the National Institutes of Health (P20), and the South
Carolina EPSCoR/IDeA office (CCD grant).
 Special thanks: Dr. Scott Little of the State EPSCoR
office, Dr. Douglas B. Chrisey of RPI, Drs. Roger
Markwald, Vladimir Mironov, and Joann Sullivan of MUSC,
and Dr. Jeremy Tzeng of Clemson
 Students: Yafu Lin, Leigh Herran, Wei Wang, Nicole
Coutris, and Wenxuan Chai
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