The purpose of this paper is a new thin-film based sensor proposed for sensitive and selective detection of mercury (Hg2+) ions in water. The thin-film platform is easy to use and quick for heavy metal ions (HMIs) detection in the picomolar range. Ion-selective self-assembled monolayer's (SAM) of thiol used for the detection of HMIs above the Au/Ti top surface.
A thin-film based platform is suitable for the on-field experiments and testing of water samples. HMIs (antigen) and thiol-based SAM (antibody) interaction results change in surface morphology and topography. In this study, the authors have used different characterization techniques to check the selectivity of the proposed method. This change in the morphology and topography of thin-film sensor checked with Fourier-transform infrared spectroscopy, surface-enhanced Raman scattering spectroscopy, atomic force microscopy and scanning electron microscopy with energy dispersive x-ray analysis used for high-resolution images.
This thin-film based platform is straightforward to use and suitable for real-time detection of HMIs at the picomolar range. This thin-film based sensor platform capable of achieving a lower limit of detection (LOD) 27.42 ng/mL (136.56 pM) using SAM of Homocysteine-Pyridinedicarboxylic acid to detect Hg2+ ions.
A thin-film based technology is perfect for real-time testing and removal of HMIs, but the LOD is higher as compared to microcantilever-based devices.
The excessive use and commercialization of nanoparticle (NPs) are quickly expanding their toxic impact on health and the environment. The proposed method used the combination of thin-film and NPs, to overcome the limitation of NPs-based technique and have picomolar (136.56 pM) range of HMIs detection. The proposed thin-film-based sensor shows excellent repeatability and the method is highly reliable for toxic Hg2+ ions detection. The main advantage of the proposed thin-film sensor is its ability to selectively remove the Hg2+ ions from water samples just like a filter and a sensor for detection at picomolar range makes this method best among the other current-state of the art techniques.
The authors are thankful to Director CSIR-CEERI, Pilani and Sardar Vallabhbhai National Institute of Technology, Surat for support and encouragement. Also, like to thank “Visvesvaraya PhD Scheme for Electronics and information technology” funded by the Ministry of Electronics and Information Technology. Also, like to thank the project fellow Mr. Ajay Kumar (AFM analysis), Technical Officer Mr Prateek Kothari (FTIR analysis), Sr. Technician Mr Ashok Kumar Sharma SERS spectroscopy) and Senior Technical Officer Dr Maninder Kaur (SEM/EDX analysis). Authors also acknowledge support by Science and Engineering Research Board, Department of Science and Technology India under project No EMR/2016/006279.
Rotake, D.R., Darji, A. and Singh, J. (2020), "Thin-film based sensor for the selective detection of mercury (Hg2+) ions at the picomolar range", Sensor Review, Vol. 40 No. 4, pp. 485-495. https://doi.org/10.1108/SR-12-2019-0313Download as .RIS
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