Repeatability tests were performed to ensure the reproducibility of the results. The performance of the devices for different urea concentrations (1mM, 1µM, 1nm and 1pM) is reported in the supporting information from Non-invasive paper-based microfluidic device for ultra-low detection of urea through enzyme catalysis SureshVignesh QunyaOng KantaBera Lakshmi YuhLee Yeong S. L. ChongKaren 2018 Plots of current vs time performed to demonstrate the repeatability and reproducibility of the results of the paper fluidic devices in sensing urea