All-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers

Area of Science:

• Photonics
• Microfluidics
• Sensing Technologies

Background:

• Whispering-gallery mode resonators are crucial for sensing but often rely on expensive, complex fabrication methods.
• Existing microresonator fabrication, like silica microtoroids, involves challenging vacuum-based processes.
• There is a need for cost-effective, scalable, and disposable photonic sensing platforms.

Purpose of the Study:

• To present an all-polymer photonic sensing platform using microgoblet lasers integrated into microfluidic chips.
• To demonstrate a fabrication method that is solution-based and scalable, reducing costs compared to traditional techniques.
• To validate the platform's performance in refractometric sensing applications.

Main Methods:

• Fabrication of poly(methyl methacrylate) (PMMA) microgoblet cavities using spin-coating, optical lithography, wet etching, and parallel thermal reflow.
• Integration of doped microgoblets (pyrromethene 597) to create microgoblet lasers.
• Assembly of laser arrays into injection-molded microfluidic chips for lab-on-a-chip applications.

Main Results:

• Achieved microgoblet cavities with quality factors exceeding 10^5.
• Demonstrated low lasing thresholds (< 0.6 nJ/pulse) for doped microgoblets, efficiently pumped by a green laser diode.
• Validated refractometric sensing capability with a bulk refractive index sensitivity (BRIS) of 10.56 nm/RIU.

Conclusions:

• The all-polymer platform offers a cost-effective and scalable alternative to silica-based resonators.
• The developed microfluidic chip with microgoblet lasers is suitable for disposable sensing applications.
• The platform shows significant potential for various lab-on-a-chip sensing applications, particularly refractometric sensing.