Size Control of Nanoparticles Using a Microfluidic

Abstract — We have developed a microfluidic device system for the continuous producing of nanoparticles, and we have clarified the relationship between the mixing performance of reactors and the particle size. First, we evaluated the mixing performance of reactors by carrying out the Villermaux – Dushman reaction and determined the experimental conditions for producing AgCl nanoparticles. Next, we produced AgCl nanoparticles and evaluated the mixing performance and the particle size. We found that as the mixing performance improves the size of produced particles decreases and the particle size distribution becomes sharper. We produced AgCl nanoparticles with a size of 86nm using the microfluidic device that had the best mixing performance among the three reactors we tested in this study; the coefficient of variation ( Cv ) of the size distribution of the produced nanoparticles was 26.1%. Keywords — Microfluidic, Mixing, Nanoparticle, Silver Chloride. I. I NTRODUCTION ICROMACHINING techniques have been adopted in the design of miniaturized devices, e.g. microfluidic devices, for chemical synthetic applications [1]-[3]. A microfluidic device is a reactor in which chemical reactions can be performed carried out on a microscale [4], [5]. The potential advantages of using a microfluidic device, rather than a conventional batch reactor, are as follows: the temperature can be controlled effectively in a microfluidic device; the fluids to be mixed have a laminar flow, and mixing progresses rapidly because of the short diffusion length of the materials in the microfluidic device. Because of these advantages, recently, microfluidic devices have been used in the field of nanotechnology. We can produce nanoparticles using a microfluidic device by controlling nucleation, particle growth, and aggregation. Since rapid and uniform mixing can occur in a microfluidic device in the nucleation stage, the duration of the particle growth stage can be kept constant. Therefore, uniform particles can be continuously produced. The production of fine nanoparticles using a microfluidic device has been reported in many papers. For example, Maki et al. [6], produced Au nanoparticles using microfluidic devices under various conditions, e.g., for different concentrations, residence times, and types of microfluidic devices. Thus, they were able to effectively control the size of the produced Au