Fully inkjet-printed distance-based paper microfluidic devices for colorimetric calcium determination using ion-selective optodes

摘要: Although the determination of calcium ions (Ca2+) is high importance to monitor water hardness, currently available devices for on-site analysis suffer from a lack user-friendliness and sensitivity. This work demonstrates fully inkjet-printed low-cost microfluidic paper-based analytical (μPADs) simple naked-eye colorimetric in drinking tap samples. The quantification Ca2+ relies on visual readout length colour-changed detection channel modified with ionophore-doped ion-selective optode nanospheres (nano-optodes), eliminating requirement scanner or camera. All fabrication steps deposition assay reagents have been performed by means desktop thermal inkjet printer, which expected contribute highly batch-to-batch reproducible device preparation. detectable concentrations between 0.05 mmol L−1 5 cover range recommended International Organization Standardization (0.05–2.5 L−1) World Health (WHO) guideline (less than L−1). lowest concentration naked eye was found be L−1, below value achieved previously reported devices. μPAD quantified waters were within 15% error results obtained classical complexometric titration. Hence, distance-based μPADs relying nano-optodes are sensitive tools equipment-free assaying real