A MEMS (Micro-Electro-Mechanical Systems) microcantilever biosensor is a sophisticated device used for biomolecular detection at the microscale level. It leverages the principles of microfabrication and mechanical deflection to detect the presence of specific biomolecules, such as proteins, DNA, or even whole cells, within a sample. The operation of a MEMS microcantilever biosensor involves several key steps:
Design and Fabrication: The sensor is fabricated using microfabrication techniques commonly employed in the semiconductor industry. This involves depositing layers of materials, such as silicon, onto a substrate to create the cantilever structure. The cantilever is usually a thin, elongated beam anchored at one end to the substrate, allowing it to move freely.
Functionalization: The surface of the cantilever is functionalized with a specific receptor molecule. These receptor molecules are designed to selectively bind to the target biomolecules of interest. For instance, in a DNA detection application, the receptors might be single-stranded DNA sequences complementary to the target DNA strands.
Sample Application: The sample containing the biomolecules is introduced to the sensor. If the target biomolecules are present in the sample, they will bind to the receptor molecules on the cantilever's surface.
Mechanical Deflection: The binding of biomolecules causes a change in the mass distribution on the cantilever's surface. This change in mass results in a mechanical deflection or bending of the cantilever. The extent of deflection is proportional to the mass of the bound biomolecules and is usually measured in nanometers.
Detection Mechanism: The cantilever's deflection is detected using various methods, such as optical, piezoresistive, or capacitive techniques. In an optical setup, for instance, a laser beam may be directed onto the cantilever, and the deflection-induced change in the reflected light's angle is measured.
Signal Analysis: The measured deflection or signal is then processed and analyzed. By comparing the deflection with a calibration curve or a known standard, the concentration of the target biomolecule in the sample can be determined.
Sensitivity and Specificity: The performance of the biosensor depends on factors like the sensitivity of the cantilever to mass changes, the specificity of the receptor-target interaction, and the noise in the measurement system. The sensitivity can be enhanced by optimizing the cantilever's design, functionalization process, and detection mechanism.
Advantages of MEMS Microcantilever Biosensors:
They offer rapid detection with potential real-time monitoring.
They require only small sample volumes.
They can be miniaturized and integrated into lab-on-a-chip systems.
They are label-free, reducing the need for complex sample preparation.
Applications:
DNA sequencing and genotyping.
Protein-protein interaction studies.
Pathogen detection in medical diagnostics.
Environmental monitoring.
Drug screening and development.
Overall, MEMS microcantilever biosensors provide a powerful tool for biomolecular detection, offering high sensitivity and the potential for integration into various analytical platforms.