PAPER: Can particles move and deposit, from 25 to 40 deg-C surface? ~40℃表面に微粒子を集積させた流体の制御技術

Why 40 deg. C ?  This study considered the deposition of submicron particles on living-cell or “human-body”-modelled surface.

Why a fluorescence microscope? Because other analytical tools such as SEM, need low pressure or vacuum condition, which is not “good” for living-system.

空気・液体界面への粒子の輸送を模倣するために、エアロゾル・フロー・システムが構築された。An aerosol flow system has been constructed to mimic the delivery of particles to the air-liquid interface. A colloidal suspension of submicron fluorescent core-shell silica-based particles was sprayed by an ultrasonic nebulizer. The dynamics of the aerosol settling was investigated by numerical simulation to determine the carrier gas flow rate, which was further verified through experimentation.

Fluorescent microscopy was used to observe the particles deposited on the substrate. It was found that the apparent (fluorescent) size distribution was shifted from 2.9 ± 6.0 μm to 1.7 ± 2.2 μm, which is correlated to the changes of aggregate size from 0.70 μm to 0.24 μm due to the changes in the colloidal suspension concentration. In addition, the uniformity of the particles dispersed on the substrate was not significantly affected by the suspension’s concentration, as confirmed by the inter-particle distance analysis.

It is therefore suggested that the method presented here may potentially be applied for the deposition and analysis of submicron particles on various types of substrate (i.e. air-liquid interface) without the need for vacuum imaging analysis (e.g. electron microscopy).