Abstract: Described herein is an assay device, comprising a substrate comprising microfluidic geometry, and a reagent layer disposed adjacent to the substrate.

Abstract: Disclosed herein are lateral flow devices that can sensitively detect an analyte in a sample by using two different populations of nanoparticles. An example device comprises a porous substrate, the porous substrate comprising a sample zone, the sample zone including a detection nanoparticle and a control nanoparticle, wherein the detection nanoparticle and the control nanoparticle each include a different detection label; and a detection zone, the detection zone including a test line and a control line downstream from the test line. Also disclosed are methods and kits including the devices.