Abstract
A microfluidic paper-based impedimetric device was developed as a water hardness sensor. This device is capable of performing the analysis with a sample volume of few microliters with no prior treatments. A phenol-formaldehyde graphene electrode modified with ethylenediaminetetraacetate was used as the working electrode. Ag pseudo reference and carbon electrodes were used to fabricate the device. Current simultaneous metal ion detection sensors are based on complex and expensive electrode setups. The proposed inexpensive, quick and portable device is capable of detecting Ca2+ and Mg2+ simultaneously. Electrode double layer-based charge transfer resistance and the maximum negative imaginary impedance produced a linear correlation with each metal ion concentration. The calculated limits of detection for Ca2+ and Mg2+ were 0.31 and 0.24 ppm, respectively. A set of samples containing Ca2+ and Mg2+ with a hardness of 2 ppm (as calcium carbonate) were used to test the device. The proposed tool is suitable as a semi-quantitative device for the determination of hardness in water.
Highlights
Miniature microfluidic paper-based devices can be used effectively to monitor parameters in many fields such as environmental, clinical, food and pharmaceutical applications.[1]
Colorimetric[3] and amperometric[4] methods are common detection methods used in μPad. Such a paper-based device for the determination of water hardness can reduce the cost of the water hardness testing method
Compared to most other ion-selective electrode methods that are based on liquid or gel fillings, the proposed paper-based device has a greater shelf life and this impedimetric μPad can be directly used without any initial setup steps
Summary
Miniature microfluidic paper-based devices (μPad) can be used effectively to monitor parameters in many fields such as environmental, clinical, food and pharmaceutical applications.[1]. Ion-selective electrode[5] based potentiometric methods can be used for the determination of water hardness. Compared to these methods, the proposed paper-based method is inexpensive. Compared to most other ion-selective electrode methods that are based on liquid or gel fillings, the proposed paper-based device has a greater shelf life and this impedimetric μPad can be directly used without any initial setup steps. The use of impedimetric methods as the detection technique in paper-based devices for metal ions. Few paper-based impedimetric devices were reported previously for the detection of biological parameters.[6],[7] Work reported in this paper describes μPad that uses impedimetric based detection for the simultaneous detection of Ca2+ and Mg2+ ions.
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