| abstract |
The invention features an assay device, a microfluidic device, and a method of detecting the presence of high electrolyte concentration in a fluid sample. The assay device comprises a porous, hydrophilic substrate; a fluid-impermeable barrier defining a boundary of an assay region and a boundary of a main channel region, the main channel region fluidically connected to the assay region; and a strip of conductive material disposed on the porous, hydrophilic substrate. The microfluidic device comprises a porous, hydrophilic substrate; a fluid-impermeable barrier, the barrier permeating the thickness of the porous, hydrophilic substrate and defining within the porous, hydrophilic substrate a boundary of an open-ended channel having first and second lateral walls; and an electrically conductive pathway disposed on the porous, hydrophilic substrate, the electrically conductive pathway comprising (i) a strip of conductive material forming an open circuit in the absence of an electrically conductive material bridging the first and second lateral walls; and (ii) a battery, an electrically-responsive indicator, and a resistor electrically connected to the strip of conductive material. |