Colloid-facilitated migration has been significantly concerned with the acceleration of the radionuclide mobility in the HLW repository. In the repository system, the compacted bentonite, which is the buffer material, could be the major source for colloid generation; hence, the understanding of colloid generation from the bentonite is the essential to expect the colloid-facilitated radionuclide migration. This study aimed to investigate the colloid generation using a bentonite-based micro-scale flow path system, which called microfluidics. In order to fabricate the microfluidics, direct milling method was applied to make a mold by computer numerical control. The fabricated mold applied to prepare the microfluidic chip by Polydimethylsiloxane (PDMS), in which the size of microchannel was designed to be one micrometer. Initially, sylgard 184 and curing agent mixed and stirred for 10 min, afterwards the bubbles in the paste was removed in the vacuum desiccator for 30 min. Then the paste was poured into the mold, and finally dried for 4 hours at 80°C in a dry oven. The compacted Ca-bentonite chip was prepared by the cold isostatic pressing (CIP) method with the dry density of 1.6 g·cm−3. The microfluidic chip and compacted bentonite chip were assembled by an acryl jig, the flow rate was adjusted by 20 mL syringe equipped syringe pump. The degree of colloid generation accompanied with the erosion of bentonite was gravimetrically examined after the experiment. The effect of the pH and ionic strength on the colloid formation was investigated through the particle size, stability and aggregation. To the best of our knowledge, this is the first examination for the colloid generation using microfluidics; these results would give information to understand the colloid formation from the compacted Ca-bentonite in the HLW repository system.

본 총설에서는 마이크로플루딕스 기술에 대한 기초연구를 소개하고, 이 기술을 통하여 화장품산업분야에서 응용성이 큰 동공구조체, 응답성 소재, 캡슐 소재, 다층 콜로이드 구조체 등과 같은 신소재의 합성이 가능함을 기술한다. 마이크로플루딕스 기술이 적용되어 개발된 기능성 신소재들은 그 크기와 내부 모폴로지를 정확하게 피코리터 수준에서 조절할 수 있다. 또한, 소재의 화학조성을 다양하게 임의 조절할 수 있고, 고차 층구조를 갖는 콜로이드 입자나 캡슐의 개발까지도 가능하여 그 응용성은 무궁무진하다고 할 수 있다. 기본적으로 약물전달계, 화학물 분리공정, 바이오센서, 애튜에이터 등의 응용연구에 매우 유용하게 활용될 수 있다. 화장품산업에서도 마이크로플루딕스 기술을 이용하여 고기능성 신소재 개발이나 신유형 화장품 개발이 가능할 것으로 기대되어 더욱 복합적인 연구개발이 진행되어야 할 것이다.