Sticking yourself in the finger day after day. For
many diabetics, this means of checking blood glucose
is an everyday part of life. Especially for patients
with Type-1 diabetes, who always have to keep a
close eye on their levels, since their bodies are
incapable of producing the insulin to break down the
glucose in the blood.
Several times a day, they have to place a tiny drop
of blood on a test strip. It is the only way they
can ascertain the blood glucose value, so they can
inject the correct amount of insulin needed. And
this pricking is not only a burdensome: it may also
cause inflammation or cornification of the skin. And
for pain-sensitive patients, the procedure is agony.
The daily sticking of the finger may soon become a
thing of the past, thanks to a diagnostic system
with Fraunhofer technology built-in. The underlying
concept is a biosensor that is located on the
patient’s body. It is also able to measure glucose
levels continuously using tissue fluids other than
blood, such as in sweat or tears. The patient could
dispense with the constant needle pricks. In the
past, such bioelectric sensors were too big, too
imprecise and consumed too much power. Researchers
at the Fraunhofer Institute for Microelectronic
Circuits and Systems IMS in Duisburg have recently
achieved a major breakthrough: They have developed a
biosensor in nano-form that circumvents these
hurdles.
The principle of measurement involves an
electrochemical reaction that is activated with the
aid of an enzyme. Glucose oxidase converts glucose
into hydrogen peroxide (H2O2) and other chemicals
whose concentration can be measured with a
potentiostat. This measurement is used for
calculating the glucose level.
The special feature of this biosensor: the chip,
measuring just 0.5 x 2.0 millimeters, can fit more
than just the nanopotentiostat itself. Indeed,
Fraunhofer researchers have attached the entire
diagnostic system to it. “It even has an integrated
analog digital converter that converts the
electrochemical signals into digital data,” explains
Tom Zimmermann, business unit manager at IMS. The
biosensor transmits the data via a wireless
interface, for example to a mobile receiver. Thus,
the patient can keep a steady eye on his or her
glucose level. “In the past, you used to need a
circuit board the size of a half-sheet of paper,”
says Zimmermann. “And you also had to have a driver.
But even these things are no longer necessary with
our new sensor.”
The minimal size is not the only thing that provides
a substantial advantage over previous biosensors of
this type. In addition, the sensor consumes
substantially less power. Earlier systems required
about 500 microamperes at five volts; now, it is
less than 100 microamperes. That increases the
durability of the system – allowing the patient to
wear the sensor for weeks, or even months. The use
of a passive system makes this durability possible.
The sensor is able to send and receive data
packages, but it can also be supplied with power
through radio frequency.
The glucose sensor was engineered by the researchers
at Noviosens, a Dutch medical technology firm. Since
it can be manufactured so cost-effectively, it is
best suited for mass production. These non-invasive
measuring devices for monitoring blood glucose
levels may become the basis for a particularly
useful further development in the future: The
biochip could control an implanted miniature pump
that, based on the glucose value measured, indicates
the precise amount of insulin to administer. That
way, diabetes patients could say goodbye to
incessant needle-pricks forever.
For more information
http://www.fraunhofer.de/en.html
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