Figure 1.

Schematic illustration of the paper-based microfluidic device that enables ultra-low detection of analytes (urea). Analytes enter through the entry port, and flow through the channel via capillary action, before reaching the reaction zone, which is preloaded with enzymes (urease). An enzymatic reaction takes place in the reaction zone, generating ions that result in current flow between the electrodes. The electrodes are screen printed using silver paste.