Analyzing refractive index changes and differential bending in microcantilever arrays

Area of Science:

• Biosensing
• Nanotechnology
• Biophysics

Background:

• Microcantilever arrays are used for detecting biomolecules.
• Refractive index changes can interfere with optical readout systems.
• Existing designs may suffer from artifacts due to environmental factors.

Purpose of the Study:

• To introduce and investigate a new microcantilever array design.
• To mitigate the influence of refractive index variations on biosensing measurements.
• To analyze molecular stress formation using differential curvature during pH experiments.

Main Methods:

• Design and fabrication of a microcantilever array with eight flexible cantilevers and two solid bars.
• Utilizing an optical laser readout system for detecting cantilever bending.
• Performing experiments with varying DNA, protein, salt concentrations, and pH levels.

Main Results:

• The new design effectively subtracts refractive index contributions for picomolar to micromolar concentrations of DNA and proteins.
• Measurements in high salt concentrations or serum are affected by refractive index artifacts, necessitating corrections.
• Differential curvature analysis provided insights into molecular stress formation during pH experiments.

Conclusions:

• The developed microcantilever array design enhances the accuracy of optical biosensing by reducing refractive index artifacts.
• The system shows promise for sensitive detection of biomolecules at low concentrations.
• Further corrections are needed for complex samples like serum or high salt solutions to maintain measurement integrity.