Highlights:
- Transparent biosensors developed
using low cost semiconductor material have
been embedded on contact lenses to detect glucose levels
- These can be worn by the patient and will help in continuous
monitoring of the patient
- The biosensors will help in early detection of illnesses
Doctors could soon
monitor
blood glucose
levels without invasive tests. Dr. Gregory S. Herman and colleagues
from the Oregon State University have developed transparent biosensors which when embedded into contact lenses could soon be used to identify telltale
illnesses. The technology incorporated into these biosensors is similar to the
ones used in the development of smartphones that have extra vivid displays. They can be used to
identify cancer as well as other serious illnesses and for tracking drug use.
A biosensor is a device which utilizes biological
molecules or living organisms that include antibodies
or enzymes to identify the presence of certain other components. They are minimally invasive and do not harm the
body.
‘Biosensor contact lenses are designed to detect very small quantities of glucose making the suitable for early diagnosis and continuous monitoring’
This unique
biosensor was presented at the 253rd National Meeting & Exposition of the
American Chemical Society (ACS). Dr. Herman said that though these sensors will
not eliminate the need for blood tests there is a lot of diagnostic information
that can be gathered from a tear drop.
Touch Screen Sensitivity and Biosensors
The concept of
developing a biosensor occurred to Dr.Herman while he worked in an industrial
set up, revolutionizing electronics by teaming up with two of his colleagues to
develop the compound composed of
indium gallium zinc oxide (IGZO). This
semiconductor offered consumers high quality displays with superior resolution
for smartphones, televisions and tablets, enhancing touch screen sensitivity
and saving power.
Dr. Herman moved
to Oregon University and began to delve deeper into the biomedical aspects of
this semiconductor technology. He was motivated to find a method by which
people with
diabetes could
monitor their sugar level continuously using these biosensor lenses.
Limitations in the Current Method of
Diabetes Detection
- A small 'prick and blood test' is currently used to monitor blood
sugar levels. The method is invasive and continuous monitoring is not
possible. Moreover, pricking too often can be tiresome.
- Continuous glucose monitoring normally requires the use of electrodes
that are inserted into the skin at various sites, which is painful or
could lead to skin irritations.
Advantages of Bio-sensing Contact
Lenses
Dr. Herman stated
that the limitations associated with the current methods of testing could be
eliminated with bio-sensing contact lenses.
- They can be used for continuous monitoring
- They are non-invasive
- Compliance could be improved as the individual can replace it every
day
- They are transparent which will not make the individual self-conscious
The first step
towards developing this continuous diabetes monitoring system was by developing
methods that were inexpensive. The biosensor was fabricated using a transparent
sheet of IGZO field-effect transistors with glucose oxidase. This enzyme is instrumental in breaking down glucose. When glucose was added to the mixture, the enzyme was found to oxidize the blood sugar which increased the pH of the mixture and brought about changes in the
flow of current passing through the IGZO transistor.
The electrical
changes that occur when used in conventional biosensors can be used to measure the glucose concentrations present in the
interstitial fluid present below the skin of the patient. However, the glucose
concentrations present in the eye are very low. To overcome the low levels of
glucose, the IGZO biosensors were designed with nanostructures which are highly
sensitive to trace even small amounts of glucose.
The biosensor can be designed to include more than 2,500 biosensors, with each
biosensor measuring various functions of the body. They can be placed in a
1-millimeter square patch of an IGZO contact lens. The biosensors are being
developed to transmit essential information to smartphones and other devices
that are wifi enabled.
Previous studies
with the biosensors involve its use to indicate kidney
function by measuring uric acid. It could take another year before this
biosensor can be used for animal studies. The biosensor can also be used for efficient delivery of drugs, especially for ocular conditions.
Biosensors to detect
glucose Levels in saliva
Biosensors are
being carefully designed to improve technology based medical diagnosis. A
research team from Hong Kong Polytechnic University developed a biosensor which
was sensitive to glucose. This biosensor detects the level of glucose by
identifying the electric current In the saliva.
This biosensor was
found to detect glucose levels that were as low as 10-5mmol/L which is a lot
more sensitive than conventional methods of detection. They are cost effective
and can even be used on human skin and as wearable technology.
There are several
other biosensors that are being keenly developed like the
uric acid sensors and the
cholesterol
sensor. These sensors are revolutionizing medical diagnosis and will help
in detecting medical conditions early, sometimes even before the symptoms
actually set it.
Reference: - Highly sensitive biosensor for measuring glucose in
saliva - (https://phys.org/news/2016-04-highly-sensitive-biosensor-glucose-saliva.html)
- Smart contact lens and smart eye glasses
- (http://www.frontiersin.org/10.3389/conf.FBIOE.2016.01.01493/2893/10th_World_Biomaterials_Congress/all_events/event_abstract)
Source: Medindia
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