Massive Parallel Assembly of Microbeads for Fabrication of Microtools Having Spherical Structure and Powerful Manipulation by Optical Tweezers

Hisataka Maruyama, Ryo Iitsuka, Kazuhisa Onda, and Fumihito Arai

Production of functional microtools having an arbitrary shape by self-assembly of microparticles and heat treatment above the glass transition temperature of the microparticles was developed. Polystyrene microbeads were used as a material of the microtool. A solution including microparticles was dispersed onto the silicon substrate having microtool patterns fabricated by photolithography and etching. Dispersed particles were introduced to the pattern by gravity force. Microparticles in the pattern aggregate autonomously by surface tension through evaporation of the solution. Aggregated microparticles were fused by heating above the glass transition temperature (100°C). Fused microparticles were detached from the pattern by ultrasonic treatment and used as microtools. Produced microtool has spherical part since the microtool is made of microparticles. Spherical part is suitable for trapping point of optical tweezers. We demonstrated production of microtools using self-assembly and manipulation of the fabricated microtool on a chip.

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