A simple and effective droplet electric separator microfluidic device was developed for cell sorting. The aqueous droplet without precharging operation was influenced to move a distance in the channel along the electric field direction by applying dc voltage on the electrodes beside the channel, which made the target droplet flowing to the collector. Single droplet can be isolated in a sorting rate of ∼100 Hz with microelectrodes under a required pulse. Single or multiple mammalian cell (HePG2) encapsulated in the surfactant free alginate droplet could be sorted out respectively. This method may be used for single cell operation or analysis.

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The authors report a feasible and simple microfluidic approach for synthesizing anisotropic gel particles based on template method. By filling arrays of microwells with alginate hydrogel and synthesizing gold nanoparticles ͑AuNPs͒ on the gel surface, anisotropic alginate gel particles with single side gold nanoparticles layers were produced in microwells on the polydimethylsiloxan template. AuNPs and the anisotropic feature were characterized using scanning electron microscopy and x-ray photoelectron spectrum analyses. The anisotropic particles made of biocompatible gels could be released from the template and collected with uniform sizes, which might have a powerful potential in biological detection and sensing.

We reported a novel method to fabricate both spherical and nonspherical PDMS (Polydimethylsiloxane) particles of amphiphilic property. PDMS particles were first obtained using microfluidic devices. A layer of PAA (poly (acrylic acid)) polymer was then selectively grafted on a section of particle surface. After modification, PDMS particles exhibited an amphiphilic property. We demonstrated the assembly of spherical particles at the water/oil interface as well as the deformation of cuboidal particles which possessed a bowl-shaped structure after deformation.