ABSTRACT
This paper describes a dynamic system-a system that develops order only when dissipating energy-comprising millimeter to centimeter scale gears that self-assemble into a simple machine at a fluid/air interface. The gears are driven externally and indirectly by magnetic interactions; they are made of poly(dimethylsiloxane) (PDMS) or magnetically doped PDMS, and fabricated by soft lithography. Transfer of torque between gears can take place through three different mechanisms: mechanical interaction, hydrodynamic shear, and capillarity/overlap of menisci. Interplay between these forces allows interactions and motions that are not possible with conventional systems of gears.
ABSTRACT
This paper describes a microfluidic immunoassay that is applicable to the parallel determination of multiple analytes and that requires only a few microliters of sample. This assay relies on a microchannel network that achieves serial dilution of analytes; this network replaces manual dilutions employed in traditional immunoassays and enables the analysis of multiple analytes simultaneously. The immunoassay was demonstrated by an analysis of concentrations of antibodies against the HIV viral proteins gp120 and gp41 in human serum.
Subject(s)
Antibodies/analysis , Antigens/analysis , Fluoroimmunoassay/methods , Fluoroimmunoassay/instrumentation , HIV Antibodies/blood , Immunoglobulin G/analysis , Microchemistry/instrumentation , Microchemistry/methods , Miniaturization/instrumentation , Miniaturization/methods , Serum Albumin, Bovine/chemistryABSTRACT
This review describes the design and fabrication of microfluidic systems in poly(dimethylsiloxane) (PDMS). PDMS is a soft polymer with attractive physical and chemical properties: elasticity, optical transparency, flexible surface chemistry, low permeability to water, and low electrical conductivity. Soft lithography makes fabrication of microfluidic systems in PDMS particularly easy. Integration of components, and interfacing of devices with the user, is also convenient and simpler in PDMS than in systems made in hard materials. Fabrication of both single and multilayer microfluidic systems is straightforward in PDMS. Several components are described in detail: a passive chaotic mixer, pneumatically actuated switches and valves, a magnetic filter, functional membranes, and optical components.
