If550

A commercial microscope system (Olympus, IX83) was customized to achieve automated polarized light imaging. A circular polarizer with a wavelength range of 400–700nm (Edmund Optics, #88-099) and an interference bandpass filter centered at 535nm with a pass-band of 64.4nm (Olympus, IF550) were placed in the illumination path to achieve circularly polarized light illumination. In the image acquisition path, four linear polarizers (Chroma, 21003b) were placed into a motorized filter wheel (Prior Scientific Inc., HF108SIX3) to perform serial image acquisition at 4 polarization angles. The images were acquired with a 16bit CMOS camera (Hamamatsu, Flash 4.0 LT).

The plasmonic imaging system was built on an inverted microscope (Olympus IX-81) with a 60× (NA 1.49) oil immersion objective. The light source was a SLED (SLD260-HP-TOW-PD-670, Superlum) with a wavelength of 670 nm. The plasmonic image of the particles was recorded with a CMOS camera (ORCAFlash 4.0, Hamamatsu) at up to 1000 frames per second. Simultaneous transmitted light imaging was achieved by installing an image splitter (OptoSplit II, Cairn Research) between the microscope and the camera. The light source for the transmitted channel was the stocking halogen of the microscope with a green filter at wavelength of 480–550 nm (IF550, Olympus). The shear flow was generated in a PDMS channel (cross-section: 600 μm × 25 μm) using a syringe pump (Fusion 100, Chemyx).