All-optical microfluidic chips for reconfigurable dielectrophoretic trapping through SLM light induced patterning.

Area of Science:

• Microfluidics
• Materials Science
• Optics

Background:

• Fabricating microfluidic devices often requires complex molding processes.
• Dielectrophoresis (DEP) is a powerful technique for manipulating micro- and nanoparticles.
• Integrating DEP capabilities directly onto microfluidic channels presents fabrication challenges.

Purpose of the Study:

• To develop a novel, all-optical, mould-free method for fabricating microfluidic-channelled dielectrophoretic (DEP) chips.
• To demonstrate the integration of microfluidic channels and reconfigurable DEP traps onto a single substrate.
• To investigate the trapping and chaining of carbon nanotubes (CNTs) and graphite nanofibers using the fabricated DEP chips.

Main Methods:

• Utilized direct laser projection via a holographic Spatial-Light-Modulator (SLM) onto photorefractive crystals (Fe-doped lithium niobate).
• Employed an all-optical, mould-free approach to fabricate polydimethylsiloxane (PDMS) microfluidic channels.
• Created geometrically flexible DEP traps by projecting arbitrary light intensity patterns using the SLM.

Main Results:

• Successfully fabricated PDMS microfluidic channels directly onto functionalized crystal substrates.
• Demonstrated the creation of reconfigurable DEP traps using the SLM holographic projection system.
• Experimentally verified the trapping of flowing carbon nanotubes (CNTs) and observed chaining effects with graphite nanofibers.

Conclusions:

• The SLM-based holographic projection offers a versatile, mould-free fabrication route for microfluidic DEP chips.
• This approach enables the integration of microfluidics and reconfigurable dielectrophoretic manipulation on a single chip.
• The technology shows promise for applications in nanomaterial manipulation and assembly, particularly for carbon nanotubes.