Fig. 1.

DLD-based detection of bioparticles using coated micro-bead substrate. a Adhering bioparticles on to the surface of micro-beads causing overall change in surface charge and size of bioparticle-microbead conjugates. Two mechanisms proposed to increase the apparent diameter (D_app) for detection using b electrostatic charge repulsion depicted by the negatively charged pillars and bead, and c size increase of the bioparticle-microbead conjugate. d Shows the DLD device schematics, which can sensitively detect a lateral shift of a 10 µg mL⁻¹ albumin coated with a mixture of uncoated 1 µm PS-COOH beads. Lateral shifts in the DLD output spectrum can be correlated to the corresponding D_app. The black line shows the input position of the microbead sample, magenta band represents where D_app = 350 nm (0.35 µm), and yellow band represents the maximum displaced spectrum of 1000 nm (1 µm). Scale bar is 50 µm