Fiber loop ringdown DNA and bacteria sensors.

Area of Science:

• Biomedical Engineering
• Optoelectronics
• Molecular Diagnostics

Background:

• Refractive index-based sensors are crucial for label-free biomolecule detection.
• Existing methods often face limitations in sensitivity and complexity.
• Evanescent field sensing offers high surface sensitivity but requires advanced techniques for signal enhancement.

Purpose of the Study:

• To introduce a novel fiber loop ringdown evanescent field (FLRD-EF) biosensor.
• To demonstrate enhanced sensitivity and label-free detection capabilities.
• To showcase the potential for creating simple, low-cost, and highly sensitive biosensing arrays.

Main Methods:

• Utilized a partially-etched single mode fiber as the sensor head.
• Employed a fiber loop ringdown evanescent field (FLRD-EF) sensing scheme.
• Implemented stepwise coating with poly-L-lysine and probe DNA for surface sensing.

Main Results:

• Achieved bulk index-based detection of three single-strand DNA types and one bacterium.
• Demonstrated label-free target DNA sensing using surface index changes.
• The ringdown technique enhanced detection sensitivity through its multipass nature.

Conclusions:

• The FLRD-EF biosensor is a promising platform for sensitive biomolecule detection.
• The developed sensor exhibits superior simplicity, low cost, and high sensitivity compared to existing technologies.
• Future development of FLRD-EF biosensor arrays could revolutionize molecular diagnostics.