Plasmonic-Enhanced Floating Electrode Optoelectronic Tweezers (FEOET) for Effective Optical Droplet Manipulation

A plasmonic-enhanced floating electrode optoelectronic tweezers (FEOET) device is presented for effective optical droplet manipulation. Due to the importance of having a high-quality photoconductive layer, conventional FEOET devices face the issue between ineffective dielectrophoretic (DEP) performance and cost-ineffective fabrication. In this study, the use of metallic nanoparticles enables plasmonic light scattering to significantly enhance light absorption onto a photoconductive layer of the device, resulting in a largely improved DEP performance. Two numerical simulation studies have demonstrated the working principle of plasmonic-enhanced DEP and were further validated experimentally by an improved spectrophotometric light absorbance of the TiOPc layer, as well as demonstrating an 11-fold increase in light-actuated droplet speed. With much-improved DEP performance, this plasmonic-enhanced FEOET technology can provide a low-cost solution for various digital microfluidic (DMF) applications with the benefits of device simplicity.