Patent ID: 7258837

Claim:
A microfluidic device for detecting the presence of an analyte in a fluid sample comprising: a) a microfluidic channel comprising a bottom wall, two side walls and a top wall and having an upstream end and a downstream end; b) a fluid inlet in fluidic connection with the microfluidic channel; c) a storage area on one of the walls of the microfluidic channel downstream of the fluid inlet; d) at least one dissolvable solid reagent plug fixed in the storage area, the plug comprising a matrix material and a reagent having an affinity for binding to the analyte, wherein the storage area is positioned as to allow dissolution of the reagent into a carrier fluid flowing in the microfluidic channel; and e) a detection area comprising a binding wall comprising a coating having an affinity for the reagent, the detection area positioned within the microfluidic channel and downstream of the carrier fluid inlet and the storage area such that the reagent dissolved in the carrier fluid binds to the coating and forms a gradient of bound reagent.