Biosensors are analytical devices that measure biological and chemical reactions by generating signals proportioned to the concentration of the analyte in the reaction. They consist of a bioreceptor that can detect a specific biological (or chemical) element and a transducer that converts the energy form through a process known as ‘signalisation’. Biosensors are commonly used in areas such as biomedical diagnosis, forensics, drug discovery, food control, and environmental monitoring1–3.
Components of a Biosensor
- Analyte: A substance that needs detection. For example, glucose is an analyte in a biosensor that is made to detect glucose.
- Bioreceptor: A molecule that specifically recognizes the analyte. Signal generation in different forms with interaction between the analyte and bioreceptor is called bio-recognition.
- Transducer: The transducer converts the energy form from one into another. The main role of the transducer is to convert a bio-recognition event into a measurable signal via a process known as signalisation.
- Electronics: It typically processes the signal and prepares it for display.
- Display: user-friendly hardware and software generates display1–3.

Historical Background
Even though the history of biosensors date back to as early as 1906, the first true biosensor was developed by Leland C. Clark Jr in 1956 for oxygen detection. however, the first biosensor was commercialized in 1975 by Yellow Spring Instruments and was designed to detect glucose levels in blood2,3.
Characteristics of a Biosensor
Every biosensor possesses certain properties that affect its performance.
- Selectivity: Selectivity is the main consideration when developing a biosensor, and probably the most important one. It is the ability to detect a specific analyte in a mixed sample.
- Reproducibility: Reproducibility is the ability of a biosensor to provide identical responses for a duplicated set-up in an experiment and is characterized by precision. Precision is the ability of the biosensor to provide alike results every time a sample is measured.
- Stability: Degree of susceptibility to the disturbances around the system. Disturbances may cause drifts in the output signals which can cause errors in measured concentration.
- Sensitivity: Minimum amount of analyte that a biosensor can detect. In numerous medical & environmental monitoring applications, a biosensor is required to detect analyte concentrations as low as ng/ml or even Fg/ml.
- Linearity: Accuracy of the measured response to a straight line2,3.
Nanotechnology and Biosensors
Regardless of the field, miniaturisation has always been found beneficial for various reasons. In the case of manufacturing biosensors, we can list some of these benefits below:
- Reduced size (micro/nanoscale) results in a better signal-to-noise ratio
- Smaller sample volumes which lead to lower costs
- The surface-to-volume ratio of the sensing active area increases and the sizes of the detecting electrode and that of the target biomarker become comparable, which causes both reduced non-specific binding and increased binding efficiency towards target molecule. As a result, bioreceptor becomes an active transducer for the sensing system, making it possible to perform single-molecule detection1–3,5–7.
The discovery of graphene, graphene oxide, and carbon nanotubes opened new horizons for research and application. The general working principle of nanobiosensors is similar to macro- and micro-counterparts; however, they are constructed using nanoscale components for signaling and/or data transformation5–7.
Biosensor Application
Biosensors have quite a wide range of applications to improve our life quality. Nowadays, they are ubiquitous in varying areas of healthcare. They are used as technologically advanced devices both in limited-resource settings and sophisticated medical set-ups. Two main examples of the common range of biosensor applications are pregnancy tests and glucose monitoring sensors1–3. Other fields included in the application are displayed in the figure below.

Impacts and Challenges of Biosensors
Biosensors have major positive outcomes in both the academia and industry. In academia, it unites researchers from many areas such as engineers, life scientists, physical scientists and more. They have huge impacts on homeland defense and security, agriculture, food safety, medicine and pharmacology. Even though the positive impacts are inevitable, challenges within development and application still occur 3d electrochemical glucose biosensors, very few of them have achieved global success at the retail level1–3. We can list three main reasons responsible for this:
- Academic research is difficult to translate into commercially viable prototypes
- Complex regulatory issues in clinical applications
- Hard to bring researchers from different areas together and hard to find researchers with a biosensor technology background2.
To sum up, in vitro molecular biosensors are ubiquitous in biomedical diagnosis and research. They feed from many areas such as physical and life sciences, thus bringing researchers with various backgrounds together. Developments in nanotechnology and nanoscience caused rapid development in the biosensor area. They have been designed to make our life easier and they continue to do so with each device manufactured2.
References:
- Vinay Kumar J, N S, Srinivas S, Khosla A, R HK, C M. Review on Biosensors: Fundamentals, Classifications, Characteristics, Simulations, and Potential Applications. ECS Trans. 2022;107(1):13005-13029. doi:10.1149/10701.13005ECST/XML
- Mehrotra P. Biosensors and their applications – A review. J Oral Biol Craniofac Res. 2016;6(2):153-159. doi:10.1016/J.JOBCR.2015.12.002 sections 1,3 and 4.
- Bhalla N, Jolly P, Formisano N, Estrela P. Introduction to biosensors. Essays Biochem. 2016;60(1):1. doi:10.1042/EBC20150001 sections 1,2,3,4,5,6 and 7.
- Naresh V, Lee N. A Review on Biosensors and Recent Development of Nanostructured Materials-Enabled Biosensors. Sensors 2021, Vol 21, Page 1109. 2021;21(4):1109. doi:10.3390/S21041109 sections 1,2,3,4.
- Kulkarni MB, Ayachit NH, Aminabhavi TM. Biosensors and Microfluidic Biosensors: From Fabrication to Application. Biosensors 2022, Vol 12, Page 543. 2022;12(7):543. doi:10.3390/BIOS12070543 sections 1,2,3,4,5,6
- Metkar SK, Girigoswami K. Diagnostic biosensors in medicine – A review. Biocatal Agric Biotechnol. 2019;17:271-283. doi:10.1016/J.BCAB.2018.11.029 sections 1,2,5
Figure References:
- Bhalla N, Jolly P, Formisano N, Estrela P. Introduction to biosensors. Essays Biochem. 2016;60(1):1. doi:10.1042/EBC20150001
- Biosensor : Types, Interfacing, Characteristics & Its Applications. Accessed September 18, 2023. https://www.watelectronics.com/biosensor/
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