Home Uncategorized Future bio-sensors will be drawn on with ballpoint pens

Future bio-sensors will be drawn on with ballpoint pens

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Ballpoint pens loaded with sensor-laden inks could eliminate finger
pricks for diabetics, and help them test their blood glucose levels
simply by drawing cartoons – or just a few dots – on their skin. 

The
innovative new ink could also be used to test for pollutants in the
environment by drawing on leaves or on buildings’ surfaces, and could
help soldiers search for explosives and chemical weapons, the developers
say. 
The team of engineers from the University of California, San Diego,
who developed the ink, used it to fill up regular, off-the-shelf
ballpoint pens. The aim was to enable a new type of do-it-yourself
sensor with rapid diagnostic capabilities for people with diabetes. 
The
ink is made from the enzymes glucose oxidase, which responds to sugar
in the blood, and tyrosinase, which can help detect common pollutants
known as phenols. These compounds are found in cosmetics and can be toxic at high enough concentrations. 

Charles Choi explains for IEEE Spectrum what else was needed to make the inks operate like on-demand sensors: “To
make these bio-inks serve as electrodes, they added electrically
conductive graphite powder. They also added: chitosan, a clotting agent
used in bandages, to help the ink stick to surfaces; xylitol, a sugar
substitute, to help stabilize the enzymes during chemical reactions; and
biocompatible polyethylene glycol, which is used in several drug
delivery applications, to help bind all these ingredients together.” 

The team has described its “enzymatic ink” and do-it-yourself sensor in the journal Advanced Healthcare Materials. 
Using their pens, they were able to draw sensors to measure glucose directly onto the wrist of a willing participant. They say this ink drawing could be “easily interfaced with a Bluetooth-enabled” device that can provide the read-out. 
The researchers also used the ink to draw on and measure chemicals on leaves, and according to Choi at IEEE Spectrum, “the inks could be modified to react with many other pollutants, such as heavy metals or pesticides”. 
The
main purpose of the ink, and probably the most immediate impact, will
be to enable multiple-use testing strips for diabetes monitoring. As the
authors note in their paper, handheld glucose metres rely on single use sensor strips, and each test is expensive for the user. 
They
demonstrated that when applied to a flexible strip that included an
electrode, their ink functioned like a sensor. When a blood drop from a
pricked finger was placed on the sensor, the ink reacted and the sensor
measured this reaction, accurately determining the blood sugar level.
Importantly, the researchers say their ink only needs to be wiped off for the strip to be re-used – and they say one pen-load has enough ink for 500 tests. 

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The authors write that
the most attractive feature of their pen “is the immense freedom
available to incorporate high-fidelity inexpensive sensors of any design
on a wide variety of surfaces with minimal user training.”
The same team has previously developed temporary tattoos to help diabetics continuously monitor their blood-sugar levels. They say
the next step is to connect the sensors wirelessly to monitoring
devices and test their performance in different climatic conditions.
Source: IEEE Spectrum

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