My research has focused on the collective assembly behavior and dynamics of micron-sized building blocks, whose properties we can design and regulate. In particular, we introduce the mechanism of converting energy from other sources to mechanical force for individual constituents, so the assembly structures and dynamics are distinctly different from and more exciting than traditional equilibrium assembly. Research of these problems will help us to 1) understand the principles and rules of assembly at length scales close to single cells and 2) design artificial systems that can mimic the sophisticated functions of life in many different aspects. We acknowledge and respect the complexity and perplexity of life; as non-biologists, we aim to design synthetic as well as purify and modify biological materials to construct simplified model systems and study specific problems. As always, we are prepared to be surprised by the experimental results.
Dynamic & active assembly
The structure and chemistry of biological bodies from nature after millions of years of evolution and optimization has inspired the development of a large variety of biomimetic materials. However, the mechanism and underlying assembly rules in a dynamic manner remain largely unexplored. We have designed Janus colloidal particles that can self-propel and interact with others using the energy supplied by externally applied electric field. Moreover, the interaction between particles can be conveniently tuned remotely, so rich dynamic behavior can be observed and investigated in one system.
Another active system we are interested in is based on purified microtubules and kinesin motors, which are responsible for intracellular and cellular transport in cells. We use purified components in vitro to construct active polymer networks and study a series of interesting problems relevant to non-equilibrium hydrodynamics and reversed energy cascade unique to active systems.
Directed transport behavior under noise
The physiological conditions where life is present and functional are usually water based. And it is always noisy. Dynamic pathways with a lot of uncertainties are an essential route prebiotic materials took to become living matter. Inspired by this rule of thumb in the biological world, we aim to make constructive use of biasing random noise in the service of new practical engineering problems, such as designing microscopic limbless swimmers and enabling spontaneous accumulation of matter. Understanding physical laws of motion and assembly rules in physiological conditions is of fundamental importance, as well as practical potential of guiding the design of soft robots and medical devices operating in living cells.
Ordering & effective interactions in complex system
Unlike oversimplified model systems, real life systems are usually crowded with a large variety of coexisting materials. Moreover, these systems are maintained out of equilibrium, which makes it more challenging to study the interactions and ordering processes. We design mixtures of active and passive components with different functionalities to probe the effective interactions between components in complex environments, with the help of well-controlled external field as energy supplier, trigger or force gauge.