Electrochemical detection of calcium and magnesium in water bodies

• Published in: Sensors and actuators. A. Physical. Vol. 305; p. 111949
• Main Authors: Akhter, Fowzia, Nag, Anindya, Alahi, Md Eshrat E., Liu, Hangrui, Mukhopadhyay, Subhas Chandra
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-04-2020; Elsevier BV
• Subjects: Calcium; Carbon nanotubes; Chemical sensors; Curve fitting; Electrochemical analysis; Electrodes; Equivalent circuits; Flexible components; Impedance; Lactic acid; Magnesium; Molds; Multi wall carbon nanotubes; PDMS; Polydimethylsiloxane; Polylactic acid; Reactance; Reproducibility; Sensors; Substrates; Three dimensional printing; Carbon nanotubes; Magnesium; Calcium; Impedance; PDMS
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2020.111949

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•3D printed moulds were used to fabricate MWCNTs/PDMS sensor patches.•The casting technique was used to develop the electrodes and substrate of the sensor patches.•The electrodes of the prototypes were shaped in an interdigitated manner, operating on impedance spectroscopy.•Experiments were conducted with different temperatures and different concentrations of calcium and magnesium in the water bodies.•The sensor patches were able to detect and distinguish the analyte, further approving the reproducibility of the experimental results.
The design, fabrication, and implementation of novel flexible sensors for electrochemical detection of multiple minerals such as calcium and magnesium in water bodies are presented in this paper. 3D printing technique was utilized to form the master moulds for developing the sensor prototype. The 3D printed moulds were developed initially using Poly Lactic Acid as the printing filament. Multi-Walled Carbon Nanotubes and Polydimethylsiloxane were used for forming the electrodes and substrates of the sensor patches, respectively. The casting of Multi-Walled Carbon Nanotubes powder and Polydimethylsiloxane were done on the 3D printed moulds. The electrodes were patterned in an interdigitated manner to operate on the impedimetric principle. The passive elements of the equivalent circuit of the interdigitated sensors were determined using Complex Non-Linear Least-Square Curve Fitting software. The total change in impedance concerning differently concentrated solutions was due to different resistive and reactive elements of the sensors. The resistance, reactance, and impedance values from the sensor patches were analysed during the experiment for calcium and magnesium solutions. Experimental outcomes proved that the sensor was able to differentiate various concentrations of calcium and magnesium ions between 1 ppm and 200 ppm solutions. The reproducibility, repeatability, and reusability of the sensors were also tested to propose the developed sensors as an alternative solution for the determination of calcium and magnesium ions from unknown samples.