Surface plasmon tweezers-induced nanoparticle patterning in microfluidics

Here we report on dynamic patterning of nanoparticles in microfluidic channels using patterned surface plasmon polaritons (SPP) from a gold thin film with highly ordered nanohole arrays. In particular, the constructive interference of SPPs from neighboring holes leads to a periodic distribution of SPP intensities. Such a SPP distribution drives the nanoparticles into positions of minimal SPP intensities, where the net force is minimal and nanoparticles are most stable. This distribution comprises the patterning of nanoparticles. This technique is simple and cost-effective in fabrication, and only requires a laser intensity of 1/10,000 of that used in conventional optical tweezers, implying less damage to the targeted nanoparticles..