Electrokinetically-driven microfluidics
AC electroosmotic flow micromixing local pattern study
Efficient mixing of fluids in lab-on-a-chip devices is very important for many biomedical and biochemical applications. Lab-on-a-foil as novel concept provides method for fast prototyping or mass production of microfluidic device based on thin and flexible films materials. In this article, electroosmosis micromixing is conducted in a lab-on-a-foil microfluidic device. With the electroosmotic flow, an efficient micromixing is realized inside a microchannel by tooth-shaped planar electrodes. The mixing performance is evaluated based on intensity measurement, and frequency sweeping is used to identify optimal performance. Furthermore, according to local intensity profiles, the EOF pattern is analyzed to provide a deep understanding on the influence of frequency and flow rate. The amplitude of voltage and the number of pairs of electrode tooth are also investigated to find the optimal conditions of the device. To the best of our knowledge, this is the first demonstration of the AC EOF in a lab-on-a-foil device and the exploration of EOF pattern vertically and horizontally in the microchannels. This study provides a method to optimize mixing performance in EOF based micromixer. Furthermore, the fabrication method cast the potential to mass production of low-cost flexible microfluidic mixers.
Dielectrophoresis manipulation of microparticles (Red blood cells/Circulating tumor cells)
Circulating tumour cells (CTCs) are a vital biomarker for cancer diagnosis and therapy by providing real-time in vitro information and its separation plays an important role in cancer diagnosis. A simple, low-cost, electric lab-on-a-foil microfluidic platform for CTCs separation is designed and constructed. Disposable thin films are cut by xurography and microelectrode array are made with rapid ink-jet printing. The multilayer platform design allows the studying of spatial movements of CTCs and red blood cells (RBCs) under dielectrophoresis. A numerical simulation was performed to find optimum driving frequency of RBCs and the crossover frequency for CTCs. Under the optimum frequency, the RBCs was lifted 120 μm in z-axis direction by DEP force and CTCs was not affected due to the negligible DEP force at crossover frequency. By utilizing the displacement difference, the separation of CTCs (modelled with A549 lung carcinoma cells) from RBCs in z-axis direction was achieved. With the nonuniform electric field at optimized driving frequency, the RBCs were trapped in the cavities above the microchannel. The platform casts the possibilities not only for 3D high-throughput cell separation, but also for future development of 3D cells manipulation with a low-cost and rapid fabrication.