The refractive index (RI) dictates interaction between light and nanoparticles and therefore is important to health, environmental, and materials sciences. Using nanoparticle tracking analysis, we have determined the RI of heterogeneous particles <500 nm in suspension. We demonstrate feasibility of distinguishing silica and polystyrene beads based on their RI. The hitherto unknown RI of extrace...

The spectro-angular light scattering measurements of individual microscopic objects are presented. Using spectroscopic quantitative phase microscopy and Fourier transform light scattering, the 2D angle-resolved light scattering intensity and phase patterns are measured in a spectral range of 450-750 nm and an angular range of -70-70°. The spectro-angular light scattering measurements of individ...

The versatile NanoTrackerTM 2 system is designed for the optical trapping of dielectric particles and optically refractive objects. Sizes range from sub-micrometer polystyrene and silica particles (beads) to living cells with diameters of >10μm. After automated calibration of the trap-particle system, the precise and reliable measurement of piconewton forces is possible. Applications include si...

This paper reports a method for the automatic generation of hanging drops (HDs) for sustained three-dimensional (3D) cell culture. HDs emerge automatically through openings at the bottom of a microfluidic channel, which provides a means of and control over the mass transport into and out of the HD. We demonstrated the automatic formation of an array of HDs of various sizes using a microfluidic ...

Opto-thermocapillary flow-addressed bubble (OFB) microrobots are a potential tool for the efficient transportation of micro-objects. This microrobot system uses light patterns to generate thermal gradients within a liquid medium, creating thermocapillary forces that actuate the bubble microrobots. An interactive control system that includes scanning mirrors and a touchscreen interface was devel...

Microbeads that are both paramagnetic and fluorescently labeled are commercially available in colors spanning the visible spectrum. Although these commercial beads can be bright, polydispersity in both size and fluorescent intensity limit their use in quantitative assays. Very recently, more monodisperse beads have become available, but their large size and surface properties make them less tha...