PAPER: A flow system for positioning submicron particles on (40 deg. C) surface. 流体の制御で40℃の表面に微粒子を集積させた

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

Why a fluorescence microscope? Because other analytical tools such as SEM, work in low pressure or vacuum, which is not matched with living-system.

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).

Comsol

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。サブミクロンの蛍光コアシェル型シリカ系粒子のコロイド懸濁液を超音波ネブライザーで噴霧した。エアロゾル粒子沈降のダイナミクスを数値シミュレーションにより調べ、キャリアガス流速を決定した。これらは実験により確認された。非真空イメージング技術である蛍光顕微鏡法を用いて、基板上に堆積した粒子を観察した。

コロイド懸濁液濃度の変化による凝集体サイズの0.70μmから0.24μmへの変化は、見かけの(蛍光)サイズ分布が2.9±6.0μmから1.7±2.2μmに変化する相関が見出された。さらに、基板上に分散された粒子の均一性は、粒子間距離分析によって確認されるように、懸濁液の濃度によって有意な影響を受けなかった。従って、ここに提示された方法は、真空イメージング分析(例えば、電子顕微鏡法SEM)を必要とせずに、様々なタイプの基板(すなわち気液界面)上のサブミクロン粒子の沈着・堆積及び分析に適用される可能性があることが示唆される。

particlesizedistribution

Open/Free Accessdoi.org/10.11203/jar.33.102

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