The muPIVOT: an integrated particle image velocimeter and optical tweezers instrument for microenvironment investigations

• Published in: Measurement science & technology 2008-09, Vol.19 (9), p.095403 (11)-095403 (11)
• Main Authors: Neve, N, Lingwood, J K, Zimmerman, J, Kohles, S S, Tretheway, D C
• Format: Article
• Language: English
• ISSN: 0957-0233; 1361-6501
• DOI: 10.1088/0957-0233/19/9/095403

A novel instrument to manipulate and characterize the mechanical environment in and around microscale objects in a fluidic environment has been developed by integrating two laser-based techniques: micron-resolution particle image velocimetry (muPIV) and optical tweezers (OT). This instrument, the muPIVOT, enables a new realm of microscale studies, yet still maintains the individual capabilities of each optical technique. This was demonstrated with individual measurements of optical trap stiffness (~70 pN mum-1 for a 20 mum polystyrene sphere and a linear relationship between trap stiffness and laser power) and fluid velocities within 436 nm of a microchannel wall. The integrated device was validated by comparing computational flow predictions to the measured velocity profile around a trapped particle in either a uniform flow or an imposed, gravity-driven microchannel flow (R2 = 0.988, RMS error = 13.04 mum s-1). Interaction between both techniques is shown to be negligible for 15 mum to 35 mum diameter trapped particles subjected to fluid velocities from 50 mum s-1 to 500 mum s-1 even at the highest laser power (1.45 W). The integrated techniques will provide a unique perspective toward understanding microscale phenomena including single-cell biomechanics, non-Newtonian fluid mechanics and single particle or particle-particle hydrodynamics.