Continuous Separation of Multiple Size Microparticles using Alternating Current Dielectrophoresis in Microfluidic Device with Acupuncture Needle Electrodes

The need to continuously separate multiple microparticles is required for the recent development of lab-on-chip technology. Dielectrophoresis（DEP）-based separation device is extensively used in kinds of microfluidic applications. However, such conventional DEP-based device is relatively complicated and difficult for fabrication. A concise microfluidic device is presented for effective continuous separation of multiple size particle mixtures. A pair of acupuncture needle electrodes are creatively employed and embedded in a PDMS（poly-dimethylsiloxane） hurdle for generating non-uniform electric field thereby achieving a continuous DEP separation. The separation mechanism is that the incoming particle samples with different sizes experience different negative DEP（n DEP） forces and then they can be transported into different downstream outlets. The DEP characterizations of particles are calculated, and their trajectories are numerically predicted by considering the combined action of the incoming laminar flow and the n DEP force field for guiding the separation experiments. The device performance is verified by successfully separating a three-sized particle mixture, including polystyrene microspheres with diameters of 3 μm, 10 μm and 25 μm. The separation purity is below 70% when the flow rate ratio is less than 3.5 or more than 5.1, while the separation purity can be up to more than 90% when the flow rate ratio is between 3.5 and 5.1 and meanwhile ensure the voltage output falls in between 120 V and 150 V. Such simple DEP-based separation device has extensive applications in future microfluidic systems.

Multiple Needle Electrospinning for Fabricating Composite Nanofibers with Hierarchical Structure

Electrospinning is a powerful method for fabricating micro/nano fibers that can be applied to various fields.Composite materials with nanoscale structure can show more excellent properties than their conventional partners.Here,we reported hierarchical structured nanofibers with beads and spheres by double needle electrospinning with an auxiliary airflow.Two different spinning solutions with different concentrations were placed into different syringes.The action of airflow was able to make the two differently morphological nanofibers mixed together evenly.The results showed that the obtained nanofiber membrane has a good hierarchical structure with different morphologies.

Effects of the Multiple Needling with Shallow Insertion for Simple Obesity:A Clinical Observation on Lipid Metabolism and on the Chest,Waist and Hip Circumferences

Objective： To observe the therapeutic effects of multiple needling with shallow insertion tot simple obesity, and its influence on the chest, waist and hip circumferences, and lipid metabolism. Methods： 20 cases which match the criteria for diagnosis of simple obesity were treated by multiple needling with shallow insertion. Treatment was given once daily for 20 days as a total therapeutic course. Results： After 20 treatments, the body weight, waistline, and the serum total cholesterol （TC）, the fasting triglyceride （TG） and low-density lipoprotein （LDL） were significantly changed （P〈0.05）. Conclusion： The therapy can provide good theraoeutic effects for simple obesity.