ABSTRACT
We report on a novel sensor for characterization of nanoparticles colloidal suspensions. We employ a diffraction grating under total internal reflection for investigation of nanodisperse fluids passing through an integrated microfluidic channel. Dispersions containing polymeric, metallic, and ferromagnetic nanoparticles are studied. Using this device, we can accurately determine in real-time the specific refractive index for the nanoparticle suspension and the nanoparticle concentration. The nanoparticle concentrations can be calculated with a resolution of 0.3-0.5 wt% for polymeric nanoparticles, 0.03-0.05 wt% for metallic nanoparticles, and 0.05-0.1 wt% for ferromagnetic nanoparticles. This translates to an effective refractive index that can be determined with an accuracy of 7 x 10(-4) for the polymeric and 2 x 10(-4) for the metallic and ferromagnetic dispersions.
Subject(s)
Lasers , Materials Testing/instrumentation , Microfluidic Analytical Techniques/instrumentation , Nanoparticles/chemistry , Nanoparticles/ultrastructure , Photometry/instrumentation , Equipment Design , Equipment Failure Analysis , Materials Testing/methods , Photometry/methods , Systems IntegrationABSTRACT
We present refractometric measurements made in the 266-1064-nm spectral region with a pulsed Nd:YAG laser, and the second, third, and fourth harmonics of the laser's fundamental wavelength. The critical angle is determined by the disappearance of the diffraction orders from a metal grating, forming a microcuvette with the prism's reflecting wall. A fused-silica measuring prism is used in the experiments.
