– Parents know all too well the pain experienced by
their children - and themselves - when the time comes
for immunizations at the doctor's office.
a new MicroJet injector being developed by bioengineering
students at the University of California, Berkeley,
may help ease some of that dread by taking the needle
- and the pain - out of the equation. The MicroJet
uses an electronic actuator that could one day propel
vaccinations, insulin or other drugs through the skin
of the patient - without the device even touching
the skin - with far less pain than a hypodermic needle.
MicroJet improves upon current jet injectors now on
the market, which also forgo the conventional needle
but have less control over the volume and speed of
drug delivered. The UC Berkeley bioengineers were
able to achieve liquid jet speeds as high as 140 meters
per second, or about 315 miles per hour, with the
researchers will demonstrate their prototype during
the March 17-19 annual meeting of the National Collegiate
Inventors and Innovators Alliance (NCIIA) in San Diego.
World Health Organization advocates developing needleless
drug delivery technologies because of the problems
of contamination and disposal that go along with hypodermic
needles," said Laleh Jalilian, one of the three
UC Berkeley bioengineering undergraduates on the project.
"There are other jet injectors on the market,
but they are plagued by variability in the percentage
of liquid delivered, which means that it is difficult
to know exactly how much of the drug actually gets
into the patient. The MicroJet we are developing uses
a tunable electronic circuit to offer a finer level
of control than the air- and spring-powered models
researchers modified a traditional syringe by taking
out the needle and adding a tiny piezoelectric actuator
that propels the liquid out of the tube. The actuator
expands or contracts in response to an applied voltage.
Because the MicroJet's source of power is electrical
rather than mechanical, its range of control is continuous,
allowing a far higher level of customization than
the jet injectors used today.
jet injection systems have only three or four factory
settings, but human skin is tremendously variable,
with some skin being thicker and tougher than others,"
said Dan Fletcher, UC Berkeley assistant professor
of bioengineering and faculty advisor to the undergraduates.
"Not only are there differences from person to
person, there are significant differences within a
researchers pointed out that the palm of the hand,
for example, is tougher than the back of the hand,
and that the skin of an adult is likely to be tougher
than that of a child. They said there is a need for
an injector that can be tailored to these variations.
students were able to control the jet velocity of
the MicroJet from 33 meters per second up to 140 meters
per second. The amount of liquid they were able to
eject ranged from 45 nanoliters to 140 nanoliters.
They tested the MicroJet on agarose gel to mimic human
skin and found that they could vary the penetration
depth of the liquid from 1 to 8 millimeters.
they have not yet started tests on humans, the researchers
said the range of the injector is well beyond what
would be needed to deliver drugs through human skin.
great feature of the MicroJet is that the diameter
of the nozzle is only 70 microns, which is nearly
three times smaller than the thinnest conventional
hypodermic needles," said Marcio von Muhlen,
another of the UC Berkeley undergraduate researchers.
"Since the area of the jet stream decreases with
the square of the diameter, that's at least a nine-fold
reduction in the area of skin affected. With smaller
nozzle diameters and without the need to jam a needle
some substantial distance under your skin, you won't
trigger as many nerve receptors in the surrounding
tissue, which means a relatively pain-free experience."
current jet injectors also promise a less painful
injection, in reality, reports of pain can vary depending
upon the patient and the location of the shot. The
researchers acknowledge the real life reports, but
noted that the level of pain experienced can be a
function of the settings on the injector.
beauty of the MicroJet is that it has a wide range
of settings that can be customized to the patient's
comfort and needs," said Jalilian.
said the inspiration for the project came from the
ubiquitous inkjet printer. "The printer's ink
cartridges essentially deliver a very controlled,
repetitive shot of liquid onto the paper," he
said. "The liquid in an inkjet cartridge is propelled
at relatively low speeds, but the idea is the same."
does this signal the end of scary needles and crying
babies in doctors' offices?
don't think the MicroJet will ever replace needles
entirely, but we see this as providing an innovative
option for physicians and patients," said von
researchers noted that the precision of the MicroJet
could one day make it a good candidate for microsurgery
as well as for delivering arthritis drugs into the
joints of hands and knees, areas that are too shallow
for hypodermic needles. They even joke that the MicroJet
injector could be used to make getting tattoos much
MicroJet project began two years ago as part of the
Berkeley Summer Bioengineering Research Program, sponsored
by the Guidant Foundation. Through the program, UC
Berkeley undergraduate students compete for the chance
to participate in funded research projects with department
von Muhlen and Menzies Chen joined the MicroJet project
as part of that program. Once the program ended, the
students on the MicroJet project applied for and won
a $20,000 grant from the NCIIA to continue their research.
(Chen graduated in December 2004, but is still working
on the project).
have also been supported by UC Berkeley's College
of Engineering's Undergraduate Research Opportunities
program, which funds student research in a variety
of campus engineering labs.
not common for such innovative research projects to
be entirely run by undergraduates," said Fletcher.
"Not only have they done excellent work on the
research, they have applied for and received grants
to fund the project. This illustrates the importance
of having university programs that provide students
with initiative the opportunity to go beyond the typical
project is also part of the California Institute for
Quantitative Biomedical Research (QB3), which integrates
the fields of engineering, physics, mathematics, biology
and medical sciences at three UC campuses to catalyze
human health research.
tests are planned on animal models and cadaver skins
to fine-tune the device.