Momentum - The Magazine for Virginia Tech Mechanical Engineering Vol. 3 No. 3 Fall 2018 | Page 21

– and cells don’t attach to them because the cells are too large, at about 20
microns,” Nain explained. “So, what happens in nature is that these fibers
bundle together to form larger diameter structures from 200 nanometers
to several microns.” To put things in perspective, thousand microns fit in a
millimeter and thousand nanometers fit in a micron. To give some idea on
scaling, a strand of human hair varies in diameter anywhere from 50-200
microns.
In biomedical engineering, there has been a long-standing push to study
cell behavior using fiber networks. A popular technique to form fiber
networks that’s been used in the past couple of decades is electrospinning.
The first patent on electrospinning was issued in 1902, and electrospinning
uses a high electric charge (~5-20 kilowatts) to form a network of fibers. A
typical American home, by contrast, uses about 30 kilowatt hours of elec-
tricity per day.
“Electrospinning uses pretty high voltages,” Nain said, “but STEP does not
use any electric source to form fibers, thus providing us very high degree
of control over our fibers. That control allows us to study the role of align-
ment, fiber diameter, and orientation in cell behavior.”
MOMENTUM
FALL 2018
PAGE 21
Figure 2
Nanonet Force Microscopy (NFM) for measuring cellular forces