Fiber-optic trap-on-a-chip platform for probing low refractive index contrast biomaterials

Area of Science:

• Biophysics
• Microfluidics
• Optical Tweezers

Background:

• Dual-beam fiber trapping is a powerful technique for microparticle manipulation.
• Existing methods can be limited in compactness and versatility.
• Trapping low-contrast biomaterials like lipid vesicles presents a significant challenge.

Purpose of the Study:

• To fabricate and assess a compact dual-beam fiber trapping chip.
• To demonstrate the trapping of low-refractive-index lipid vesicles.
• To explore applications in soft biomaterial analysis.

Main Methods:

• Fabrication of a novel trap-on-a-chip device with fixed, counterpropagating optical fibers.
• Calibration of the optical trap using polystyrene microspheres.
• Demonstration of trapping and deformation of lipid vesicles using femtonewton forces.

Main Results:

• Successful trapping of low-contrast lipid vesicles (refractive index m<1.005) in solution.
• Measured scattering forces of approximately 30-49 pN per beam.
• Stable trapping and reversible deformation of vesicles achieved.

Conclusions:

• The compact fiber trapping chip is effective for manipulating microparticles, including challenging low-contrast vesicles.
• This technology offers a versatile platform for probing soft biomaterials.
• Potential applications include studies of biological cells, lipid membranes, and protein assemblies.