Chemical Etching Treatment of Polydimethylsiloxane for Smoothing Microchannel Surface

This paper investigates the surface modification process of polydimethylsiloxane (PDMS) microchannels for the improvement of the image quality in dark-field imaging with light sheet illumination inside the microchannel. However, dark-field light scattering technology in microchannels is a powerful technology used in the visualization of nanoparticles. Wet etching process using Tetrabutylammonium fluoride (TBAF) in N-methyl-2-pyrrolidinone (NMP) solvent was used for the surface modification of the PDMS microchannel, and the etch distance of PDMS with 0.68 M of TBAF in NMP solution for 10 min was evaluated as 18.8 +/- 1.8 mu m. Darkfield light scattering imaging of polystyrene nanoparticles (phi=100 nm) using light-sheet illumination was demonstrated and the attenuation of scattering light from the microchannel wall was confirmed using the microchannel with TBAF treatment. This surface modification technique improves the imaging quality with light sheet illumination.