Biosensors: The Whats, Whys & Hows

A biosensor is a shortened term for ‘biological sensor’, a combination of biological components (an enzyme, an antibody or nucleic acid) and a detector element. The use of biosensors has become popular in recent years and the widely accepted definition of a biosensor is “a self-contained analytical device that incorporates a biologically active material in contact with an appropriate transducer for the purpose of detecting the concentration of activity of chemical species in any type of sample”.

A molecular biosensor is a specialised and compact device that measures specific components in relation to our health and disease. These measurable components are called biomarkers. A biosensor is operated through a biological sample taken from our body, for example, a drop of blood.

How do Biosensors work?

A biosensor has two main functional parts- 

• A detection system called bioreceptor – this can be an enzyme, an antibody or even living cells
• A physico-chemical transducer – which helps to transform the signal captured by the bioreceptor into a readable measurement 

Biosensors are mainly categorized on the basis of the type of signal that is generated. For example-

Electrochemical biosensors – which measure changes in electric current or ion concentration

Optical biosensors – which measure optical changes such as absorbance, fluorescence, etc.)

Piezoelectric biosensors –  which measure changes in sound vibrations.

The above types can be used to detect a wide variety of biological components such as enzymes (electrochemical detection), antibodies (optical detection), and so on. 

So how and why are biosensors relevant? Let us find out.

Lately, in cancer research, biomarkers and electrochemical biosensors are used for more accurate diagnosis and preventive treatment. Biosensors hold great potential in cancer detection and monitoring the progression of tumour growth. Biomarkers i.e., the biological components detected by the biosensors are significant indicators in monitoring and providing better a better treatment approach. 

Biosensing is also applied in understanding the development of cardiovascular diseases. For instance, identifying and measuring biomolecules in bloodstream at low levels helps in evaluating diseased conditions.

Apart from this, we use biosensors quite frequently in our daily routine. For example-

• Glucometer is the most well-known and popular biosensor. It is a glucose monitoring device which measures the glucose concentration in the blood. 
• Pregnancy strip is commonly used to detect the presence of a specific antibody in the blood or urine to confirm pregnancy.
• Wearable biosensors such as smart watches, blood pressure monitoring devices, etc. have proven to be a boon to today’s lifestyle and allow us to track fitness on daily basis.
• COVID-19 antigen test – the newest invention that almost all of us are aware of because of the pandemic is also based on the principle of biosensing. This test is designed to detect the presence of Covid19 viral components antigens in our body.

The use of such biosensors and their extensive medical applications makes it very helpful for patients and doctors to get immediate results and optimize the treatment plan on time, while enabling self-management of the disease. It also allows for an early diagnosis and provides successful treatment plans as the disease progresses.

With the many beneficial applications of biosensors, nowadays a number of disorders like diabetes can be effectively monitored at home. It provides a better interface between physicians and patients and also helps in better management, while promoting the approach of personalised healthcare. 

Their enormous applications in the field of pharmacy, biomedical and healthcare sectors further put them as one of the major focus areas for future innovations. We are only getting started!