Ferro-microfluidic device for pathogen detection

In a previous work, we demonstrated that traveling wave excitations from integrated electrodes can continuously pump magnetic liquids within a microfluidic channel. The optimum excitation frequency of this pumping is strongly dependent on the hydrodynamic size of the magnetic nanoparticles, and the effect can be used to detect whenever a molecule or pathogen binds to the magnetic nanoparticles within a ferrofluid. Here, we demonstrate the bio-functionality and pathogen detection capability of a ferrofluid comprised of cobalt-ferrite-silica nanoparticles through the use of biotinylated genetically engineered peptides for inorganics (GEP´s). These biotinylated GEPI´s are specifically engineered to attach to the silica surface of the magnetic nanoparticles. Binding of streptavidin to the biotinylated GEPI´s on the surface of the magnetic nanoparticles shifts the optimum pumping frequency by an amount that corresponds to the increase in the hydrodynamic size of the nanoparticle. The combination of GEPI-enhanced ferrofluids with integrated microfluidic devices finally enables the development of highly sensitive, portable and cheap pathogen sensor chips.