Microfluidic device for manipulations of PMMA nanoparticles based on dielectrophoresis

This paper develops a microfluidic chip for programmable manipulations of polymethylmethacrylate nanoparticles (PMMA-NPs) based on dielectrophoresis (DEP), and includes the four main functions: focusing, guiding, trapping and releasing the nanoparticles. The structure of the DEP chip consists of a top electrode made of indium tin oxide (ITO), a flow chamber formed by optically clear adhesive (OCA) tape, and bottom electrodes with different patterns for different individual purposes. The bottom electrodes can be divided into three parts: the first is for focusing the suspended nanoparticles near the inlet of the flow chamber by a fish-bone type electrode operated in a positive DEP range; the second is for switching and guiding the focused nanoparticles along the electrode surface to the target area like flow passing along a virtual channel; and the third is for trapping and releasing the guided nanoparticles as they flow by the corresponding target electrode in the downstream. In order to demonstrate the sequence of DEP manipulations, a PMMA-NPs suspension is introduced to the DEP chip; the size of the PMMA-NPs is about 300nm. Furthermore, a LabVIEW program developed for sequence control and multiple inputs of AC signals is controlled by computer. As the experimental results show, multi-step manipulations of nanoparticles are successfully demonstrated in the present study. This enabling technology can not only be applied to biomedical detection on a molecular level as the nanoparticles bind with specific biomarkers, but it also makes it feasible to fabricate a chip consisting of a multiple biomarker array.