Assembly of Topographical Micropatterns with Optoelectronic Tweezers

Topographical micropatterns (TMPs), or ordered arrays of 3D features on a flat surface, have become important for a wide range of applications. A new optofluidic method based on optoelectronic tweezers to assemble TMPs from suspensions of microparticles in fluid is reported. After assembly, TMPs can be freeze-dried and then transferred to alternate substrates. 3D simulations are carried out to clarify the experimental results and techniques are developed to evaluate pattern-transfer fidelity, which is found to be >90% for a wide range of different structures. The optofluidic assembly method described here is facile and accessible, suggesting utility for a wide range of microfabrication and microassembly applications in the future.