On chip synthesis of Au nanoparticles by microwave heating

• Published in: Electronics and communications in Japan Vol. 103; no. 9; pp. 49 - 55
• Main Authors: Takeuchi, Masaya, Kishihara, Mitsuyoshi, Fukuoka, Takao, Yamaguchi, Akinobu, Utsumi, Yuichi
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.09.2020
• Subjects: Gold; Microchannels; microfluidic device; Microfluidics; microreactor; microwave heating; Miniaturization; Nanoparticles; Photon correlation spectroscopy; postwall waveguide; Waveguides
• ISSN: 1942-9533; 1942-9541
• DOI: 10.1002/ecj.12264

We demonstrated the on‐chip synthesis of Au nanoparticles achieved by a microwave‐induced reaction in a microfluidic channel. The chip structure consists of a waveguide and a microchannel through the inside of the waveguide. A postwall waveguide, in which metallic posts are continuously arranged on the side wall, is utilized to confine microwave fields. This configuration allows a solution to be inserted inside the waveguide by the microchannel passing between the metallic posts. In order to realize the miniaturization of the chip, the 24.125 GHz industrial, scientific, and medical (ISM) band is utilized instead of the commonly used 2.45 GHz ISM band. When pure water is heated in the microchannel under microwave input power of 3.0 W, temperature increases to 70°C were confirmed. In this paper, this chip is adapted to synthesize Au nanoparticles via a microwave‐induced reaction. After irradiating at a microwave power of 3.0 W and an irradiation time of 5 min, we observed absorbance and dynamic light scattering of the reactant, and the results indicated the generation of Au nanoparticles. This microwave synthesis system allows us to achieve automatic and rapid selective synthesis of nanoparticles in a solution.