1. Fabrication of SU-8 nanofibers via electrospinning
Brian Pham1, Marco Antonio Rodriguez2, Jaskawal Mann1, Lisa Huynh1, Harry
Calvin Cramer III2, Selena Romero3, Venu Polineni3, Anand Gadre3
1. School of Natural Sciences, University of California, Merced, CA 95343,
USA
2. School of Engineering, University of California, Merced, CA 95343, USA
3. Stem Cell Instrumentation Foundry, University of California, Merced, CA
95343, USA
In this project we focus on the development of polymeric electrospun nanoscale
fibers that can be used for various applications such as filtration, textile
manufacturing, and medical uses that range from tissue engineering to drug
delivery. Electrospinning is a fabrication technique in which an electrical charge
is passed through a liquid polymer using a metal syringe tip in order to draw
fibers at the size of nano or micro scale. To study the fabrication we included how
various parameters, such as needle gauge, deposition distance, voltage, flow rate,
polymer concentration, and conducting material can affect the surface
morphology of the electrospun nanofibers and their formation. The candidate
material chosen is SU8, which is an epoxy based negative photoresist. Due to its
viscous properties, SU-8 is commonly spun or spread over a surface and
processed using contact lithographic methods. The lithography exposes certain
regions of SU-8 causing crosslinking of the polymer chains and patterning the
spread into a specific structure. Nanoscale SU8 fibers were achieved by creating
two different concentrations of SU-8 solutions (100% and 94% w/v) and
manipulating multiple variables from the electrospinning, primarily voltage and
height, to find a set of parameters that could produce continuous nanofiber
structures. To achieve the optimum fiber diameters varying needle gauge between
18-23, it was determined that for the 100% SU-8 solution, optimum fibers of a
diameter of 1μm were produced at a deposition height of about 5 cm and at a
voltage range of 5.5 KV. For the 94% SU-8 solution diluted with cyclopentanone,
continuous nanofibers of a diameter of 5-7μm were produced at a height of 5.5 cm
and a voltage range of 5.8 KV. These parameters will be used to study the
reproducibility and alignment of the nanofibers for microfluidics and biomedical
applications.