2015.11.02PolyU Develops Highly Sensitive Biosensor for Measuring Glucose in Saliva

The biosensor developed by AP is ultra-sensitive to glucose in salivaThis novel biosensor is able to be fabricated with flexible substrate

Diabetic patients have to monitor blood glucose regularly and frequently, but conventional method of taking blood sample for measuring glucose level is painful. It is therefore important to develop high performance biological sensors for monitoring the glucose level at a reasonable cost. Recently, researchers in the Department of Applied Physics of The Hong Kong Polytechnic University (PolyU) have successfully developed an ultra-sensitive transistor-based biosensor which could detect glucose in saliva. The newly invented biosensor is highly sensitive to glucose and capable of measuring the range of glucose in saliva accurately in a convenient, safe and inexpensive manner.

The challenge to develop biosensor to test glucose in saliva is that the amount of glucose in saliva is too small for detection, and it requires a super sensitive biosensor to perform the job. The biosensor developed by PolyU researchers is fabricated with a glucose oxidase enzyme (GOx) layer, which is sensitive to glucose alone and nothing else. By detecting the electrical current, the glucose level can be known. However, there can be interference with current from other possible biological elements in saliva, such as dopamine, uric acid and ascorbic acid. To block such interference, researchers have coated Polyaniline (PANI) / Nafion-graphene bilayer films between the top enzyme layer and gate electrode. The strong adhesion of this top layer to the GOx layer enables the latter to stabilize and perform well in glucose detection.

Our novel biosensor is selectively sensitive to glucose, accurate, flexible and low in cost. The highly sensitive biosensor shows a detection lower limit of 10-5 mmol/L, which is nearly 1000 times sensitive than the conventional device for measuring blood glucose. This means with this biosensor, as little as 5 gram of glucose in a standard swimming pool of 50 m x 25 m x 2 m can be detected. Between the wide range of glucose level from 10-5 mmol/L up to 10 mmol/L (equivalent to 5 g – 5000 Kg of glucose in a standard swimming pool), the biosensor demonstrates linear response, which is good enough for measuring the possible range of glucose in the human body. Accuracy of the biosensor has been ascertained through laboratory experiments with repeatable results using glucose solutions of known glucose levels.

The glucose biosensor fabricated with flexible substrates can perform in a variety of curved and moving surfaces, including human skin, smart textile and medical bandage. Thus, it has great potential for development into wearable electronic applications, such as wearable biosensor for analysis of glucose level in sweat during exercise. It can also be mass produced at a low cost of HK$ 3 to 5 per test chip, which is comparable or even cheaper than the currently available commercialized products. In addition, this newly invented transistor-based biosensor platform is highly versatile. By changing to suitable enzymes, the platform can be used to measure the level of uric acid and other materials in saliva. For instance, if the biosensor is fabricated with enzyme uricase (UOx) and Polyaniline (PANI) / Nafion-graphene bilayer films, the platform can specifically be sensitive to uric acid only and other interference signals can be blocked.

The research findings on this high performance biosensors for saliva testing was published in the top material journal Advanced Materials.

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PolyU Develops Biosensor for Saliva Testing for Monitoring Glucose Level

Diabetic patients have to carry out blood glucose check on a regular and frequent basis. However, conventional method of extracting blood sample for measurement is painful. Therefore, developing high performance biological sensors for monitoring the glucose level at a reasonable cost is of great significance.

Researchers in the Department of Applied Physics of The Hong Kong Polytechnic University (PolyU) have developed an ultra-sensitive transistor-based biosensor which is capable of detecting glucose in saliva. The newly invented biosensor, which is highly sensitive to glucose and accurate in measuring the range of glucose in saliva, is a convenient, safe and inexpensive alternative for people suffering from diabetes.

When developing a biosensor for saliva testing, researchers face challenge in that the amount of glucose in saliva is too small for detection. An extraordinarily sensitive biosensor is required to perform the task. The PolyU-designed biosensor is fabricated with a glucose oxidase enzyme (GOx) layer, which is sensitive to glucose alone and nothing else. After detecting the electrical current, the glucose level can be revealed. To block such interference from other possible biological elements in saliva (e.g. dopamine, uric acid and ascorbic acid), researchers have coated Polyaniline (PANI) / Nafion-graphene bilayer films between the top enzyme layer and gate electrode. The strength of adhesion between this top layer and the GOx layer is strong enough, enabling the latter to stabilize and perform well in glucose detection.

The highly sensitive biosensor for saliva testing displays a detection lower limit of 10-5 mmol/L, which is nearly 1000 times sensitive than the conventional device for measuring blood glucose. Accuracy of the biosensor has been ascertained through experiments with repeatable results using glucose solutions of known glucose levels. It can also be mass produced at a low cost of HK$ 3 to 5 per test chip, which is less expensive in comparison to the currently available commercialized products.

The glucose biosensor fabricated with flexible substrates can also be applied on curved and moving surfaces, such as human skin, smart textile and medical bandage. It can therefore be fit into wearable electronic applications, such as wearable biosensor for analyzing blood glucose level in sweat during exercise.

The research findings on the high performance biosensors for saliva testing was published in the top-notch material journal Advanced Materials.

Press Contacts

Dr. YAN Feng

Associate Professor, Department of Applied Physics

Email(852) 2766 4054
Emailfeng.yan@polyu.edu.hk
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