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We present the microfabrication and characterization of a ball valve micropump in glass, which is magnetically actuated using the sinusoidal current of an external electromagnet. We employ the use of a simple powder blasting technology for microstructuring the glass substrates and fusion bonding for assembly of the multi-layered microfluidic chip. The use of a polymer membrane with embedded permanent magnet gives rise to a large actuation stroke, making the micropump bubble-tolerant and self-priming. The micropump exhibits a backpressure as high as 280 mbar and water flow rates up to 5 mL/min thanks to the large magnetic actuation force and the use of high-efficiency ball valves. The frequency-dependent characteristics are in excellent agreement with a hydrodynamic damped oscillator model.

We propose an original concept to perform a complete on-chip sandwich immunoassay on magnetic nanoparticles that are self-assembled in chains in a uniform magnetic field. The magnetic chains are retained over periodically enlarged cross sections of a microfluidic channel. Thereby they strongly interact with the flow and rapidly capture the total of a low number of target molecules from nanoliter sample volumes. As an example, we demonstrate the detection of murine monoclonal antibodies in a noncompetitive sandwich immunoassay with a detection limit of 1 ng mL(-1) in nanoliters of hybridoma cell culture medium.

We present a valveless micropump in glass, which is magnetically actuated using the sinusoidal current of an external electromagnet. We employ a powder blasting microerosion process for microstructuring the glass substrates and fusion bonding for assembly of the multi-layered microfluidic chip. The reciprocating type micropump contains two nozzle/diffuser elements and a poly(dimethylsiloxane) membrane with embedded permanent magnet. The micropump is self-priming and exhibits a backpressure of 50 mbar and water flow rates up to 1 mL/min. The flow resonance frequency is in excellent agreement with the model of Olsson et al.

We use magnetic microbeads, which are magnetically self-assembled in chains in a microfluidic chip, as reaction substrates to implement two different sandwich immunoassay protocols for the detection of mouse monoclonal target antibodies. The magnetic chains form when the chip is placed in a magnetic field, and are geometrically trapped and accurately positioned in a microchannel with periodically enlarged cross-sections. In the first immunoassay protocol, capture and target antibodies are incubated offchip, while exposure to the detection antibody is performed on-chip. In the second protocol, the complete immunoassay is fully executed on-chip. In the 'off-chip incubation-onchip detection' protocol, antibodies can be detected down to a concentration of 50 ng/mL in a total assay time of 120 min, while consuming 1.5 mL of target antibody solution. Using the full on-chip protocol, our system is able to detect target antibodies in the range of a few ng/mL in 30 min, using only a few tens of nanoliters of target antibody solution and reagents. The 'off-chip incubation-on-chip detection' protocol is also applied for dosing antibodies obtained from the supernatant of a cell culture medium.