A rotationally focused flow (RFF) microfluidic biosensor by density difference for early-stage detectable diagnosis

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Label-free optical biosensors are crucial for point-of-care testing, offering rapid, real-time diagnostics.
• Detecting low-concentration protein biomarkers remains a challenge for early disease diagnosis, including COVID-19.
• Current methods often require complex sample preparation for biomarker detection.

Purpose of the Study:

• To enhance the sensitivity of label-free optical biosensors for improved protein biomarker detection.
• To develop a novel method for increasing the detection probability of target molecules in biosensing.
• To provide a proof-of-concept for next-generation lab-on-a-chip bioanalytical platforms.

Main Methods:

• Implementation of a Rotationally Focused Flow (RFF) technique within a T-shaped microchannel.
• Integration of RFF with label-free silicon microring resonators for biotin-streptavidin interaction studies.
• Utilizing computational fluid dynamics (CFD) simulations and fluorescent flow experiments for verification.

Main Results:

• Achieved a detection limit of 0.19 femtomolar (fM) for protein biomarkers.
• Demonstrated significant sensitivity enhancement compared to traditional single flow methods.
• Verified the efficacy of the RFF method through both simulation and experimental validation.

Conclusions:

• The RFF method effectively enhances the sensitivity of label-free optical biosensors.
• This technology offers a promising platform for ultrafast and early disease detection, such as for COVID-19.
• The study advances lab-on-a-chip bioanalytics for high-sensitivity, low-concentration biomarker detection.