What is FET Biosensor: Benefits, Applications, How It Works

Accurate biomolecule detection is vital for diagnostics and monitoring, yet traditional methods, such as PCRs, are slow and complex. Field-effect transistor (FET) biosensors offer a fast, label-free solution with high sensitivity and selectivity. In this article, we will explore FET-based biosensors, their working principles, benefits, and diverse applications in healthcare, environmental sensing, and beyond.

What are FET Biosensors?

Field-effect transistor (FET) biosensors are advanced sensing devices that use a transistor-based structure to detect biological molecules with exceptional sensitivity. Unlike traditional metal-oxide-semiconductor field-effect transistors (MOSFETs), FET biosensors replace the standard metal gate with an ion-sensitive membrane and an electrolyte. This structural modification allows them to directly interact with biomolecules, making them highly effective in biosensing applications. They are also referred to as biosensor FETs or biosensor MOSFETs.

One of their most significant features is real-time and label-free detection, allowing for continuous monitoring of biological interactions without the need for additional labeling or complex sample preparation. This eliminates extra steps, reduces costs, and provides immediate results, making them highly efficient for rapid diagnostics.

Also, FET biosensors offer versatile functionalization, meaning their surface can be chemically modified to detect a wide range of biomolecules, including proteins, nucleic acids, and small molecules. This adaptability makes them valuable for various applications, from medical diagnostics to environmental monitoring and food safety analysis. With these features, FET biosensors are shaping the future of biosensing technology, offering fast, sensitive, and flexible detection capabilities.

Primary Materials Used in FET Biosensors

The choice of material in FET biosensors plays a crucial role in their performance. Several advanced materials are commonly used, each offering unique advantages:

• Graphene: Known for its exceptional electrical conductivity and mechanical flexibility, graphene enables highly sensitive detection with fast response times. Its two-dimensional structure provides a large surface area for biomolecule interactions, making it ideal for biosensing applications.

• Carbon Nanotubes (CNTs): These cylindrical nanostructures offer high mechanical strength, flexibility, and excellent electron transport properties. Their ability to enhance signal transduction while maintaining structural integrity makes them well-suited for flexible and miniaturized biosensors.

• Silicon Nanowires (SiNWs): With a high surface-to-volume ratio and excellent scalability, SiNWs provide enhanced sensitivity by amplifying charge-based interactions. Their compatibility with standard semiconductor fabrication techniques allows for large-scale production and integration into electronic devices.

How Do FET Biosensors Work?

A FET biosensor operates using a semiconductor channel that connects two electrodes: the source and the drain. Unlike a traditional FET, which relies on a standard gate electrode to control conductivity, an FET biosensor features a bio-sensitive layer that directly interacts with target biomolecules.

When these biomolecules bind to the bio-sensitive layer, they modify the local charge environment at the semiconductor surface. This interaction changes the surface potential, which in turn affects the charge carrier density in the channel. As a result, the conductance of the channel shifts, producing a measurable electrical signal that correlates with the concentration of the target analyte.

A key aspect of this detection mechanism is the shift in the transistor’s threshold voltage due to the presence of bound biomolecules. This voltage shift alters the current flowing between the source and drain electrodes, providing a precise, real-time, and label-free method for detecting biological interactions.

Advantages of FET Biosensors

The unique design and operational principles of FET biosensors confer several advantages that set them apart from traditional sensing methods.

High Sensitivity

One of the standout features of FET biosensors is their exceptional sensitivity. The intrinsic amplification properties of FETs enable the detection of minute changes in surface potential, allowing for the identification of low-abundance biomolecules. This heightened sensitivity is particularly beneficial in early disease diagnosis, where detecting trace levels of biomarkers is crucial.

Accurate Selectivity

FET biosensors can differentiate target molecules from non-specific or interfering substances. This selectivity is achieved through the careful functionalization of the bio-sensitive layer with highly specific biological receptors. By ensuring that only the intended analyte binds to the sensor surface, FET biosensors significantly reduce false positives, leading to more accurate and reliable results. High selectivity also makes FET biosensors suitable for complex sample environments, such as blood or wastewater, where multiple substances are present but only the target molecule needs to be identified.

Enhanced Scalability

The compact nature of FET biosensors allows for significant miniaturization, facilitating their integration into portable or wearable devices. This scalability not only supports point-of-care testing and on-the-go health monitoring but also enables the development of high-throughput screening platforms. The compatibility of FET biosensors with existing semiconductor fabrication technologies further enhances their potential for widespread application.

Applications of FET Biosensors

FET biosensors have revolutionized the detection and analysis of biological molecules across various sectors. Let’s take a look at some of the applications:

Medical Diagnostics

FET biosensors have made significant advancements in medical diagnostics, offering highly sensitive and real-time detection of diseases, health indicators, and cellular activities.

• Detection of Diseases and Infections: FET biosensors are widely used to detect disease markers such as cancer biomarkers, microRNAs, and viruses. Their high specificity and real-time monitoring capabilities make them valuable tools in oncology research and clinical diagnostics. In particular, their potential for early cancer detection offers significant promise, enabling timely intervention and improving patient outcomes.

• Monitoring of Health Indicators: These sensors play a crucial role in monitoring essential health metrics, such as glucose levels in saliva, offering a non-invasive alternative for diabetes management. Moreover, they have been explored for breath analysis to detect molecular disease indicators, making them useful for early-stage disease detection and continuous health monitoring.

• Recording Signals from Cells: FET biosensors can record electrical and neurotransmitter signals from living cells, enabling researchers to study neuronal activity and brain function. This capability is particularly useful in neuroscience research, where understanding electrical signaling in neurons is critical for studying neurodegenerative diseases and brain disorders.

• Detection of Specific Biomolecules: Their ultra-sensitive nature allows for the detection of proteins, DNA sequences, and small molecules, which is essential in biomedical research and disease diagnostics. These sensors can identify even trace amounts of target biomolecules, improving the accuracy of medical tests.

Environmental Monitoring

FET biosensors are also widely used for environmental monitoring, providing a rapid and highly sensitive method to detect harmful substances in water, soil, and air.

• Detection of Heavy Metals: Heavy metal contamination poses a serious threat to both human health and ecosystems. FET biosensors have been designed to detect heavy metal ions such as lead, mercury, and cadmium in water and soil, enabling timely intervention to prevent environmental damage and human exposure.

• Detection of Pesticides: The presence of harmful pesticides in food and water supplies is a growing concern. FET biosensors have shown high efficiency in detecting organophosphorus pesticides, which are widely used in agriculture but can be hazardous to both humans and wildlife. These sensors enable real-time monitoring, improving food safety and environmental protection efforts.

Food Safety

FET biosensors are employed in the detection of harmful toxins, such as mycotoxins, which can contaminate food supplies and cause severe health issues. Their ability to provide rapid and accurate results makes them essential tools for food quality control in industries and regulatory agencies.

Unlocking Ultra-High Sensitivity with Molsentech’s BioFET Technology

FET biosensors are revolutionizing many fields, including diagnostics, environmental monitoring, and food safety by providing ultra-sensitive, real-time detection with unparalleled precision. Their ability to detect biomolecules at extremely low concentrations makes them a game-changer in fields where early and accurate detection is critical. From medical applications like early cancer screening and infectious disease detection to environmental toxicity monitoring and food safety assurance, these sensors are paving the way for a smarter, safer future.

At the forefront of this innovation is Molsentech, a pioneering biotech startup from Taiwan. Our BioFET Chip platform combines semiconductor biochip technology with proprietary surface modification techniques, system integration, and AI-powered analytics to deliver fast, highly accurate results. Our technology has already demonstrated its potential during the COVID-19 pandemic and is now unlocking new possibilities for detecting diseases such as Alzheimer’s, cancers, and emerging infectious diseases.

The future of diagnostics is happening now—are you ready to be part of it? Whether you're in healthcare, research, or industry, our BioFET solutions offer the precision and speed you need to stay ahead. Let’s collaborate to redefine detection, save lives, and push the boundaries of what’s possible. Reach out to us today and discover how our breakthrough technology can transform your field. Your next big innovation starts here.