Optofluidic hollow-core photonic crystal fibres (HC-PCF) enable low-loss propagation of light at the centre of a microfluidic channel. The resulting well-defined optical forces can be used to trap and propel microparticles  and biological cells  over long distances. The particle dynamics can be monitored using in-fibre Doppler velocimetry , offering a unique way to study viscous- and thermal forces in optofluidic channels. For example: particle propulsion experiments in air-filled HC-PCF  unveiled an unexpected optothermal trapping mechanism , which has potential applications in lab-on-a-chip devices.
Furthermore, a coherent superposition of co-propagating higher-order waveguide modes can create a mode-based "optical conveyor belt" that combines long-range transport with a positional accuracy of about 1 μm . This work led to the development of a "flying particle" sensor that maps the electric field strength along a HC-PCF by measuring the transverse displacement of an optically propelled charged microparticle . This new type of fibre-optic sensor allows the electric field to be mapped with very high positional accuracy over long distances and is suitable for otherwise inaccessible or harsh environments.
 T. G. Euser et al., Opt. Lett. 34, 3674 (2009).
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 O. A. Schmidt et al., Phys. Rev. Lett. 109, 024502 (2012).
 O. A. Schmidt et al., Opt. Express 21, 29383-29391 (2013).
 D. S. Bykov et al., Nature Phot. 9, 461–465 (2015).
Tijmen G. Euser
University of Cambridge
In 2007, Tijmen Euser completed his PhD research on "Ultrafast optical switching of photonic crystals” in the group of Prof. Willem Vos at the University of Twente and the FOM Institute for Atomic and Molecular Physics (AMOLF) in the Netherlands. Subsequently, he was a postdoctoral fellow with Prof. Philip Russell at the Max Planck Institute for the Science of Light (MPL) in Erlangen, Germany. Over the past years, his MPL team has demonstrated a range of applications of hollow-core photonic crystal fibre (HC-PCF), such as: flying-particle sensors based on microparticles that are optically guided along a HC-PCF, controlled excitation of higher-order fibre-modes, and photochemistry on sub-µl volumes in PCF. In August 2015, Tijmen was appointed to a Lectureship at the Cavendish Laboratory, where his Optofluidics lab in the Maxwell Centre for the physical sciences investigates optical manipulation of nanoparticles and biomolecules as well as photocatalysis in optofluidic waveguides.