Three-dimensional Mach-Zehnder interferometer in a microfluidic chip for spatially-resolved label-free detection

Area of Science:

• Optofluidics
• Integrated photonics
• Laser-based fabrication

Background:

• Ultrafast laser writing offers a flexible method for integrating photonic devices directly onto chips.
• Optofluidic devices combine optical sensing with microfluidic sample handling for advanced analysis.
• Label-free and spatially-resolved sensing are crucial for real-time monitoring in microfluidic systems.

Purpose of the Study:

• To demonstrate a monolithic optofluidic device in fused silica for label-free, spatially-resolved sensing.
• To integrate a Mach-Zehnder interferometer with microfluidic channels fabricated using femtosecond laser technology.
• To evaluate the sensing performance, including spatial resolution and limit of detection.

Main Methods:

• Fabrication of a monolithic optofluidic device using ultrafast laser writing in fused silica.
• Inscribing a Mach-Zehnder interferometer with its sensing arm crossing a microfluidic channel.
• Integration of the device with femtosecond laser-fabricated microchannels or commercial lab-on-chip systems.

Main Results:

• The developed optofluidic device enables label-free sensing of samples within a microfluidic channel.
• Spatially-resolved sensing with a resolution of approximately 10 micrometers was achieved.
• A limit of detection as low as 10(-4) refractive index units (RIU) was demonstrated.

Conclusions:

• Ultrafast laser writing is a powerful technique for creating complex, integrated optofluidic devices.
• The monolithic device offers significant advantages for label-free and spatially-resolved sensing in microfluidics.
• The demonstrated performance highlights the potential for applications in chemical and biological analysis.