(Digital Presentation) Novel Back gate-Field Effect Transistor (BG-FET) Based on Curcumin Functionalized Zinc Oxide Nanorods for Detection of Arsenic(III) Ions in Water
Authors: Sett Avik , Biswas Shatavisha , Bhattacharyya Tarun Kanti 
Published: July 2022

Human activities and industrial pollutants that are released regularly in the surrounding, causes toxic metallic impurities like Hg, As, Cd and Pb to accumulate and enter the water bodies in different forms. These toxic metal contaminats can cause severe biological and environmental degradation and has the capability to threat human life.

These severe consequences have led many organizations to determine maximimum quantities of metal ions in potable water and food. Safe limits for lead, mercury, arsenic and cadmium in potable water are 15,2, 10 and 5 parts per billion (ppb) respectively, as determined by EPA (Environmental Protection Agency). Various disorders in functioning of nucleic acid, immune system attack and other nervous system disorders can be caused due to repletion of As3+ in human body.

Detection of As3+ ions in drinking water in presence of other competing analytes is a challenging task. Therefore, developing sensitive and accurate techniques for monitoring these toxic metal ions in water is the need of the hour. Analytical techniques such as AAS/AES, ICP-MS, ASV that were conventionally used, require expensive instruments, incur complicated measuring techniques and are time consuming. Alternatively, various sensors are fabricated for As3+ ion detection, such as electrochemical, fluorescent, colorimetric and surface-enhanced Raman scattering. Inspite of these developments, sensors with ease of operation, portable analytical platform and low cost for user friendly analysis are still needed.

In this work, curcumin functionalized zinc oxide nanorods (Cur-ZnO) were used as an electrical sensing platform for highly selective and sensitive As3+ detection. Zinc oxide nanorods were synthesized using solvothermal approach and attachment of curcumin to ZnO nanrods were obtained through an in-situ approach. High resolution transmission electron microscopy (HRTEM), Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Ultraviolet-visible (UV-Vis) absorbance analysis were done to confirm the attachment of curcumin sheets to ZnO nanorods. The sensing platform was fabricated in a novel staggered gate-field effect transistor (SG-FET) configuration with Cur-ZnO as the sensing layer. A high-k dielectric (hafnium oxide) was used as gate dielectric and aluminium was used as gate metal. The performance of the sensor towards As3+ detection was investigated electrically by varying the gate voltage of the sensor device. The sensor was found to be highly selective towards As3+ in presence of Pb2+, Hg2+,Cd2+, Na+, Fe3+, K+ and Cu2+. The interaction of As3+ ions with the sensing layer was also studied using UV-Vis and PL spectrophotometer. The sensitivity of the sensor was seen to improve by tuning the gate voltage. Our work suggests that Cur-ZnO based staggered gate-field effect transistor (SG-FET) are promising towards development of portable, selective and sensitive arsenic ion detector in drinking water.

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