Oscillatory flow-assisted efficient target enrichment with small volumes of sample by using a particle-based microarray device.

In the study, we describe an oscillatory flow-assisted efficient target enrichment method by using a particle-based microarray device. Periodic oscillating flow effectively increased the mixing and binding performance between the target molecules in the sample solution and surface functionalized microparticles. Particles were trapped, secured, and released with an elastic microvalve structure operated via differences in the flow conditions. Single particle (20-µm diameter) trapping efficiency exceeded 95%. Secured particles can freely move inside each array element based on oscillating sample flow. Furthermore, the particles can be released from the array and collected at the outlet of the device, and this provides an opportunity for further off-chip analysis. As a proof-of-concept, we used the interaction between streptavidin-coated microparticles and fluorescence labeled biotin solution and demonstrated that target enrichment and detection based on oscillatory flow were significantly more efficient than that based on unidirectional or static flow. The applicability of the method was further examined by conducting an on-chip immunoassay to detect the presence of anti-Zika nonstructural protein 1 (NS1) monoclonal antibody. The limit of detection (LOD) was as low as 1 ng/mL with an assay time of only 10 min and less than 10 µL of sample consumption.