Contents lists available at ScienceDirect Computers and Electronics in Agriculture journal homepage: www.elsevier.com/locate/compag Flexible sensors platform for determination of cadmium concentration in soil samples Milan Radovanović a , Dragana Vasiljević a , Dejan Krstić a , Igor Antić a , Olha Korzhyk b , Goran Stojanović a, ⁎ , Biljana D. Škrbić a a University of Novi Sad (Faculty of Technical Sciences and Faculty of Technology), Novi Sad, Serbia b Lesya Ukrainka Eastern European National University, Ukraine ARTICLEINFO Keywords: PVC foils Sensors Xurographic technique Cadmium concentration ABSTRACT Efficient monitoring and measuring concentrations of heavy metals in soil is one of the utmost needs in en- vironmental monitoring. This work describes a portable sensors platform for determination of concentration of heavy metals, in our case cadmium, in soil samples. Using a cost-effective xurographic PVC foils-based tech- nique, transparent multilayer interdigitated gold-electrodes structure, with two sensors, was fabricated. The transparent sensor platform was tested measuring capacitance by means of an Impedance Analyzer and the obtained results indicated that capacitance increases with increased concentration of cadmium in soil sample. The proposed platform in combination with our portable impedance analyzer, enable fast, “green” on-site measurement of heavy metals in soil, thus, avoiding the use of some toxic chemicals necessary for sample preparation and analysis by commercial analytical instrumentations, providing less negative effects on humans’ health and environment. 1. Introduction With progress of our society and industrialization process, the concentration of heavy metals (HMs) have been dramatically increased in the environment, causing many negative effects on humans, plants, animals, etc. Exposure to HM has been linked to developmental of re- tardation, pulmonary, hepatic, skeletal, reproductive effects, various cancers, and kidney damage in human beings (Tavallali and Kazempourfard, 2009). Unlike other pollutants, HMs have long-time stability and they are nondegradable. The HMs in soil can be absorbed by plants and can cause reduction in their growth. HMs can enter in human bodies through all three medium - air, water and soil. Among all HMs, cadmium (Cd) is especially dangerous for our health, even at low concentrations, for example in food. Cd is categorized among the first eight the most hazardous substances (Winquist et al., 2009). However, Cd is unavoidable material in many industrial processes and application such as: electroplating, engraving, in dentistry, in batteries, etc. The Word Health Organization (WHO) reported tolerably weekly intakes of Cd as 0.007 mg/kg body weight for humans. Thus, Cd can dangerously affect human and other beings health even at very small concentrations (Bakirdere and Yaman, 2008). Because of this, it is very important to have precise methods for determination of Cd concentration in soil. Typical methods for detection of HMs in soil are implemented by col- lecting samples in field and transporting them to laboratories for de- tailed analysis. However, long period which pass through taking sam- ples on-site up to their analysis in laboratory may result in alteration of samples composition as a consequence of chemical, biological, and physical reactions (Zouetal.,2009). Furthermore, analysing samples in lab requires sophisticated, costly and bulky instruments. Techniques which have been used for HM determination up to now are based on spectroscopic principle, e.g. atomic emission spectroscopy (Li et al., 2004), atomic absorption spectroscopy (Báez et al., 2007, Bings et al., 2006) and inductively coupled plasma mass spectrometry (Li et al., 2015). However, these methods are not suitable for on-site application from the following reasons: time-consuming procedures, complicated sample pre-treatment, professional personnel and sophisticated (costly) instruments (He et al., 2008). Therefore, there is a strong need for development of sensors platform for determination of HMs in soil that canbeusedon-site.Numeroussensingprincipleshavebeenusedforon- site measurement of HMs, such as optical (Ensafi and Isfahani, 2007), piezoelectric (Gomes, 2001), ion selective electrodes (Ensafi et al., 2008) or lab-on-a-chip concept (Ming et al., 2013). Screen-printed sensor on rigid substrate modified with a Nafion polymer has been presented in (Wang et al, 2016), for monitoring concentrations of Pb https://doi.org/10.1016/j.compag.2019.105001 Received 11 June 2019; Received in revised form 3 August 2019; Accepted 8 September 2019 ⁎ Corresponding author. E-mail address: sgoran@uns.ac.rs (G. Stojanović). Computers and Electronics in Agriculture 166 (2019) 105001 0168-1699/ © 2019 Elsevier B.V. All rights reserved. T