ABSTRACT
Assay systems that employ protein microarrays for the analysis of complex samples are powerful tools to generate a high amount of data from a limiting amount of sample. Due to miniaturization, these systems are susceptible to fluctuations during signal generation and the use of uniform conditions for sample incubation and during the assay procedure is required to get reproducible results. Diffusion limits may prevent constant conditions on all parts of the array and can lead to the decease of the sensitivity of the array. Therefore, we set-up an automated assay system integrating a novel microagitation device using surface acoustic wave (SAW) technology. Multiplexed assays for the detection of autoantibodies from human serum and sandwich immunoassay for the detection of matrix metalloproteases (MMPs) were used to evaluate the system. Diffusion-rate limited solid phase reactions were enhanced by microagitation using the SAW technology resulting in up to three-fold higher signals.
ABSTRACT
Surface acoustic waves are used to actuate and process smallest amounts of fluids on the planar surface of a piezoelectric chip. Chemical modification of the chip surface is employed to create virtual wells and tubes to confine the liquids. Lithographically modulated wetting properties of the surface define a fluidic network, in analogy to the wiring of an electronic circuit. Acoustic radiation pressure exerted by the surface wave leads to internal streaming in the fluid and eventually to actuation of small droplets along predetermined trajectories. This way, in analogy to microelectronic circuitry, programmable biochips for a variety of assays on a chip have been realized.
