Research

Colloid and 2D Packing

Packing is a phenomenon can be observed in the entire universe. Objects with different size, shape and interaction, pack together with thousands of ordered or disordered structures. How many soy beans can be put into a box? Do pentagon and hexagon bricks fill the square? Why diamond and graphite have totally different physical properties with a same chemical formula? Questions raised connect to behaviors of packing, in different length scale, from atom to plant. Is there any universal principal between these "packing" transcend length scale?

In this project, we focused on build the connection between nano-sized molecules and micron-sized particles. A profound understanding of the molecular crystallization process may be realized if the process of assembly can be witnessed by observing the crystallization of colloidal and micron-sized particles having contours that mimic their molecular analogues. Lithographic method is employed to make millions of particles with designed shape, and particles are harvested in solution under a cleanroom environment. (Fig.1) Particles are assembled in a self-made dielectrophoresis device and this process is observed and recorded by an optic microscope. (Fig.2) By analyzing the structure of particles in colloid, we are trying to project a nano-scale event (molecules crystallizing) to a micron-scale process (particles packing), which is much easier to observe.