Medical Design Briefs - February 2022 - 34

GlobAl
INNOVATIONS
Technology Enables Needle-Free Glucose Monitoring
University of Aukland, Aukland, New Zealand
A
needle-free technology that would
allow people with diabetes to
measure blood sugar levels without
having to stick a needle into their fingertips,
has been bought closer to reality
by researchers at the Auckland Bio -
engineering Institute (ABI).
Jiali Xu and her team's research
demonstrated for the first time that a jet
injector could be used to collect blood
samples from humans - that is, release
enough blood for glucose sampling,
sans needles.
The researchers turned their attentions
to needle-free jet injection, an emerging
but well-developed technique in which a
drug is delivered directly with a high-speed
narrow jet of fluid. In a study published in
the Journal of Diabetes Science and Technology,
researchers demonstrated for the first
time that a jet injector could also be used
to collect blood samples from humans -
that is, release enough blood for glucose
sampling, sans needles.
People with diabetes typically need to
measure their blood glucose concentration
several times each day, by pricking
their fingers with a needle to release a
drop of blood which is measured by a glucose
meter, which indicates how much
insulin is required for the person to maintain
their blood sugar.
Fingertips are the preferred site for
blood sampling because they have a high
density of blood vessels. But the fingertips
are also sensitive, and pain, skin damage,
bruising and risk of infection from regular
'pricking' has spurred increasing efforts to
develop needle-free methods of blood testing
for people with diabetes.
Jet injection is appealing for a number
of reasons - including the obvious, that
many find having a needle stuck into them
extremely unpleasant. It has been the subject
of years of research, which includes
developing jet injectors for delivering
drugs such as insulin and nicotine.
Xu and her team demonstrated that the
technology could also be used to pierce
the skin with a small volume of harmless
saline solution, and this would release
enough blood for glucose concentration
measurement - that is, for extraction
rather than injection.
The study involved 20 healthy participants,
who each volunteered four fingertips,
each of which received a lancet prick
(the standard needle) and jet injection
through three differently shaped and
sized nozzles. " [The nozzles] were de -
signed to mimic the wound left from a
lancet prick, in the anticipation that it
might release blood in a way similar to a
lancet prick, " says Xu.
ab c
The study showed that indeed it did,
with some nozzle shapes performing better
than others - a 'slot' shaped nozzle
released more blood than a circle-shaped
nozzle, for instance. Most of the different
jet injection nozzles were generally perceived
as no more painful than a standard
lancet, and in some cases, less so: participants
were blinded by an opaque barrier
that prevented them from seeing the procedure
but allowed them to communicate
with the practitioner.
They were also asked to complete a
questionnaire 24 hours later, to reassess
the level of pain, swelling or bruising. It is
thought that people with diabetes might
d
find jet injection more acceptable than
using a needle although the researchers
caution against jumping to conclusions.
" When you know there's not a device that
is pricking your skin, you could speculate
that people will find jet injection more
acceptable, " says Prof. Andrew Taberner,
head of the Bioinstrumentation Lab at the
ABI, and Xu's supervisor. " But we don't
have evidence to back that up. That wasn't
part of this study. "
He was pleased, but not surprised.
" Diesel mechanics have known for years
that you should never put your finger in
front of a fuel injector, because it will inject
fuel into your finger. They found this out
the hard way. But we're taking advantage
of what diesel mechanics discovered accidentally
years ago, with a very small
amount of harmless liquid, to deliberately
release blood. "
The team is now investigating if they can
use jet injection not only to release blood,
but to suck back, to extract fluid. This
would allow for the design of an even
smaller nozzle.
They have the technology, having developed
the world's first jet injection device
that uses electric motors to pressurize the
drug - this allows for more precise control
than the more common spring-actuated
jet injector.
Moreover, " our technology has the
capability to both deliver and withdraw
fluid. No other jet projection technology
has that capacity, " says Dr. Taberner.
Research into needle-free injections is
1 mm
1 mm
1 mm
1 mm
Examples of images of fingertip intervention sites taken soon after receiving (a) lancet prick, participant
X; (b) jet injection with the cylinder nozzle, participant X; (c) jet injection with the medium slot
nozzle, participant Y; and (d) jet injection with the small slot nozzle, participant Z. (Credit: Journal of
Diabetes Science and Technology)
34
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a long game, as is the potential commercialization
of the technology he says, but
he believes Ms Xu's research will contribute
to the ultimate aim, of the development
of a single lancet-free reversible
technology that will allow for both blood
sampling and insulin delivery based on
the glucose measurement in one device.
" I hope that this research will contribute
to that, and the improvement in
human healthcare, especially in the
management of diabetes, " says Xu.
For more information, visit www.auckland.
ac.nz/en.
Medical Design Briefs, February 2022

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Medical Design Briefs - February 2022

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