Simple method to integrate in situ nano-particle focusing with cantilever detection

Real-time detection of low-concentration pathogenic/toxic bioparticles is important for deterring infectious diseases and bioterrorism, which is difficult to achieve for lab-on-a-chip. Currently, sensitivity is achieved through time-consuming culturing or sophisticated processing, often unfeasible under field conditions. Real-time particle enrichment will improve sensor capability. This paper reports a first in situ particle focusing mechanism integrated with cantilever detection. It uses AC electroosmosis to induce microfluidic convection of particles from solution bulk onto sensing electrodes, thus increasing local particle count. It is expected that with the use of preconcentrator (particle focusing), the capability of cantilever detection can be greatly improved. Also, multiplexing detection can be achieved by coating cantilevers with various sensitive layers.