Electrochemical impedance spectroscopy based MEMS sensors for phthalates detection in water and juices

Asif I. Zia*, A. R Mohd Syaifudin, S. C. Mukhopadhyay, P. L. Yu, I. H. Al-Bahadly, Chinthaka P. Gooneratne, Jrgen Kosel, Tai Shan Liao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)
195 Downloads (Pure)


Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle's equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.

Original languageEnglish
Article number012026
Pages (from-to)1-12
Number of pages12
JournalJournal of Physics: Conference Series
Issue number1
Publication statusPublished - 2013
Externally publishedYes
EventThe 6th Vacuum and Surface Sciences Conference of Asia and Australia (VASSCAA-6) - Islamabad
Duration: 9 Oct 201213 Oct 2012

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