Babak
ZIAIE, et al.
Ferropaper
Babak Ziaie
(765) 494-0725
bziaie@purdue.edu
Babak ZIAIE
'Ferropaper' is new technology for small motors,
robots
by
Emil Venere
Researchers at Purdue University have created a magnetic
"ferropaper" that might be used to make low-cost
"micromotors" for surgical instruments, tiny tweezers to
study cells and miniature speakers.
The material is made by impregnating ordinary paper - even
newsprint - with a mixture of mineral oil and "magnetic
nanoparticles" of iron oxide. The nanoparticle-laden paper
can then be moved using a magnetic field.
"Paper is a porous matrix, so you can load a lot of this
material into it," said Babak Ziaie, a professor of
electrical and computer engineering and biomedical
engineering.
The new technique represents a low-cost way to make small
stereo speakers, miniature robots or motors for a variety of
potential applications, including tweezers to manipulate
cells and flexible fingers for minimally invasive surgery.
"Because paper is very soft it won't damage cells or
tissue," Ziaie said. "It is very inexpensive to make. You
put a droplet on a piece of paper, and that is your
actuator, or motor."
Once saturated with this "ferrofluid" mixture, the paper is
coated with a biocompatible plastic film, which makes it
water resistant, prevents the fluid from evaporating and
improves mechanical properties such as strength, stiffness
and elasticity.
Findings will be detailed in a research paper being
presented during the 23rd IEEE International Conference on
Micro Electro Mechanical Systems on Jan. 24-28 in Hong Kong.
The paper was written by Ziaie, electrical engineering
doctoral student Pinghung Wei and physics doctoral student
Zhenwen Ding.
Because the technique is inexpensive and doesn't require
specialized laboratory facilities, it could be used in
community colleges and high schools to teach about micro
robots and other engineering and scientific principles,
Ziaie said.
The magnetic particles, which are commercially available,
have a diameter of about 10 nanometers, or billionths of a
meter, which is roughly 1/10,000th the width of a human
hair. Ferro is short for ferrous, or related to iron.
"You wouldn't have to use nanoparticles, but they are easier
and cheaper to manufacture than larger-size particles,"
Ziaie said. "They are commercially available at very low
cost."
The researchers used an instrument called a field-emission
scanning electron microscope to study how well the
nanoparticle mixture impregnates certain types of paper.
"All types of paper can be used, but newspaper and soft
tissue paper are especially suitable because they have good
porosity," Ziaie said.
The researchers fashioned the material into a small
cantilever, a structure resembling a diving board that can
be moved or caused to vibrate by applying a magnetic field.
"Cantilever actuators are very common, but usually they are
made from silicon, which is expensive and requires special
cleanroom facilities to manufacture," Ziaie said. "So using
the ferropaper could be a very inexpensive, simple
alternative. This is like 100 times cheaper than the silicon
devices now available."
The researchers also have experimented with other shapes and
structures resembling Origami to study more complicated
movements.
The research is based at the Birck Nanotechnology Center in
Purdue's Discovery Park.
Ferro-Paper Actuators
Zhenwen Ding, Pinghung Wei, and
Babak Ziaie
Purdue University
In this paper, we report on an inexpensive method for
fabricating mm-scale magnetic actuators using ferrofluid
impregnated paper. Different types of papers were loaded
with light oil-based ferrofluid, cut to cantilever shape,
coated with parylene C, and tested with an external magnetic
field. Cleanroom and filter paper were able to generate
large forces (>40 mg equivalent force) whereas soft
tissue paper provided the largest deflection (40° tip
angle). Coating parylene on ferro-paper not only improves
the mechanical properties but also allows the ferro-paper
actuator to work in liquid environment.