In the 20th century, coal miners kept canaries in cages with them when they worked in the mines. These canaries die if the amount of toxic gases such as methane exceeds the normal level, thereby serving as a warning signal to the coal miners so they have sufficient time to escape.

The unfortunate canaries served as a primitive form of the biosensors nowadays. Thankfully, medical biosensors have come a long way since then.

Caption: In the 20th century, coal miners kept canaries in cages with them when they worked in the mines. (Photo credit: Coachella Valley Weekly)
Caption: In the 20th century, coal miners kept canaries in cages with them when they worked in the mines. (Photo credit: Coachella Valley Weekly)
 

A highly sensitive biosensor that analyses glucose in saliva


A biosensor is a device that quantifies specific biochemical process via analysis of biological material such as enzymes, antibodies and even DNA. Every day wearable technology such as fitness trackers that detect heart rate and blood pressure are forms of biosensors. By connecting to other devices such as smartphones or computers, biosensors can provide a fast, personalized and painless snapshot of various health parameters.

Biosensors have a wide range of applications. Currently, they are mainly used in the clinical, food and agricultural sectors.

One of the most common forms of biosensors are blood-glucose monitors, which makes up 85% of the total world market of biosensors. Fuelled by the increasing numbers of diabetic patients, this enormous sector is expected to exceed USD31 billion by 2024, nearly double of its size in 2015.

Caption: In 2015, researchers in the Department of Applied Physics of PolyU developed an ultra-sensitive transistor-based biosensor that could detect glucose in saliva. (Photo credit: PolyU)
Caption: In 2015, researchers in the Department of Applied Physics of PolyU developed an ultra-sensitive transistor-based biosensor that could detect glucose in saliva. (Photo credit: PolyU)

However, traditional blood-glucose monitoring has one drawback: constant needle pricks. In 2015, the Hong Kong Polytechnic University (PolyU) sought to rectify this issue by designing a device that can detect glucose in saliva. Since there is only a small amount of glucose in saliva, the device is close to a 1000 times more sensitive than the typical blood-glucose devices in order to perform the measurement. Additionally, it is extremely versatile and can be adapted to a variety of uses just by changing the enzymes embedded on it. At only HK$3-$5 per chip, the gadget has immense potential in the future.

The widespread use of biosensors


One of the main reasons why biosensors became popular in the medical field is its ability to provide point of care testing.

"Existing methods to detect microRNAs are time consuming and require cumbersome machines, which limit their usefulness in clinical settings," said one of the researchers, Mi Kyoung Park. "This inspired us to develop a simple and efficient point-of-care device for detecting microRNAs."

The team from the Agency for Science, Technology and Research in Singapore are currently developing a silicon photonic biosensor which uses beams of light to detect tiny changes in the composition of a urine sample. By measuring the level of microRNAs in the sample, the team can possibly identify if the patients develop any types of cancer, cardiac disease or other severe health issues.

Additionally, biosensors may serve as a mean to remotely monitor the patient’s condition. In particular, chronic disease patients and elderly patients can benefit from biosensors so healthcare professionals can watch out for changes in their physical conditions.

Biosensors can also play a role in ‘self-treating’ patients. Scientists have invented clothing that are able to access the degree of tissue blood flow in different parts of the body. A small electric shock is delivered to increase blood flow to areas that are low – thereby preventing bed sores.

Two decades ago, the Georgia Institute of Technology in the United States implemented the idea of biosensors when they designed one of the first types of digital clothing for military purpose. Apart from being capable of measuring vital signs, heart rate, and breathing rate using optical fibres and sensors in the fabric, the smart clothing was also able to locate the bullet in the body of a wounded solider.

Today, the development of biosensors has experienced a robust growth. In the near future, perhaps biosensors such as smart clothing will become as ordinary as smartphones. MIMS

Read more:

Biosensors for better, faster tracking of Alzheimer's progression using beta-amyloid measurements
4 up-and-coming medical technologies that will revolutionise healthcare
10 latest medical devices and wearables for patients and healthcare professionals

Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766830/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4862100/
http://www.medgadget.com/2017/04/glucose-biosensors-market-size-to-surpass-usd-31-billion-worldwide-by-2024-hexa-research.html
https://lifesciencedaily.com/academic-research/20597-wearable-biosensors-indicate-illnesses-symptoms-show/
https://www.sciencealert.com/a-new-biosensor-could-help-on-the-spot-diagnosis-of-cancer-and-other-diseases
https://www.polyu.edu.hk/web/en/media/media_releases/index_id_6159.html