A ferrofluid micropump for lab-on-a-chip applications

A disposable micropump is presented that uses the piston actuation principle and relies on the magnetic properties of a ferrofluid, a colloidal suspension of nanosize ferromagnetic particles. The cost effective micropump consists of 7 bonded layers of polymethylmetacrylate (PMMA) that are either micromachined or structured by powder blasting. Two silicone check-valves are also integrated in the microchip. External dimensions of our prototype are 36 mm x 22 mm x 5 mm. The magnetic liquid plug is externally actuated by a motorized permanent magnet. Water has been successfully pumped at a flow rate of 30 µL/min without backpressure; pumping is demonstrated up to a backpressure of 25 mbar

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed

Particle size investigations of a multistep synthesis of PVA coated superparamagnetic nanoparticles

Nanoscaled particles showing superparamagnetic behavior have been intensively studied in the past years for various applications. Nevertheless, the lack of well-defined particles remains an important problem. One of the major challenges is still the large-scale synthesis of particles with a narrow size distribution. The aim of this work is to synthesize and characterize ferrofluids throughout a multistep synthesis. The iron oxide nanoparticles are first obtained by classical coprecipitation in water, followed by a thermochemical treatment and centrifugation to obtain well-dispersed primary nanoparticles. Finally polyvinyl alcohol is grafted onto the particles to ensure colloidal stability of the ferrofluid at neutral pH. The different synthesis steps and intermediate and side products are described. A model is proposed for the stabilization mechanism