Optofluidic control using light illuminated plasmonic nanostructure as microvalve

Optofluidic control is emerging as a promising tool in wide applications like pharmaceutics, chemistry, energy, and biology, due to the development of micro-fluidic chip. They usually require complex optical set-ups or special materials for working fluid or micro-channel. In the present work, a simple optofluidic control method using light illuminated gold nanobrick array in a distributary micro-channel was proposed. The plasmonic nanostructure acts like a microvalve which can be tuned continuously by manipulating the illumination light polarization state or intensity. Two different types of micro-channels were studied to examine the performance of the proposed method. It is found that for h-shaped micro-channel, the mass flow rate can be controlled by simply adjusting the intensity of the incident monochromatic light. As for the Y-shaped micro-channel, the manipulation of mass flow rate is achieved by changing the polarization state of the incident light. On this basis, the detailed influence factor of the light controlled microvalve is investigated to optimize its performance.