Electrical behavior of ZnO-valinomycin coated Ag electrode for the detection of K + in blood Priyabrata Pattanaik • D. K. Mishra • Jyoshnarani Mohapatra • E. Subudhi • Debi Prasad Das • Sushanta Kumar Kamilla Received: 2 October 2014 / Accepted: 7 November 2014 / Published online: 16 November 2014 Ó Springer Science+Business Media New York 2014 Abstract ZnO and ZnO-valinomycin coated over Ag substrates were prepared by chemical wet and dry tech- nique. ZnO film was grown along (101) direction due to the implication of valinomycin with it. Fibre type of micro- graphs of ZnO-valinomycin having length 8–10 lm and average diameters of 0.5 lm have been observed under scanning electron microscope. A comparative electrical studies have been carried out in between ZnO coated Ag substrate and ZnO-valinomycin coated Ag substrate to identify the suitability of the electrode. ZnO-valinomycin coated film on Ag substrate shows a very good response for K ? sensing in comparison to the ZnO coated film on Ag substrate. The increased surface area of the ZnO due to the presence of valinomycin is the prime reason for the good sensing response. This is the reason why ZnO-valinomycin coated over Ag substrate is considered for the detection of K ? in animal blood. The electrical studies clearly establish that ZnO-valinomycin coated Ag substrate is suitable to detect a small percentage of K ? ions in the blood. 1 Introduction The recent interest in the medical sciences is to develop a capable sensing instrument which can measure the bio- logical parameters of the human body like uric acid, glu- cose, cholesterol, hemoglobin, DNA and potassium etc. very accurately. Among all these parameters, presence of potassium in the human body is one of the vital parameter [1–7]. The slight variation in potassium ratio creates hypokalemia, weak muscles, abnormal heart rhythms, rise in blood pressure and also kidney problems. Hence, it is necessary to choose a perfect sensing material which can measure the slight variation of K ? in the human body during diagnosis. So, the sensor must have a sensitivity to the measured parameter, insensitivity to any other property likely to be encountered in its application and does not influence the measured property. The selection of a sensing material is an important aspect. The sensing material should be chosen so meticulously that it can accurately reproduce the biological parameters, does not get influ- enced by the environmental condition and should have a low cost. Various studies have described K ? sensors based on ion-selective electrodes [8–10]. To design a high sen- sitive electrode, reproducible and long lasting electrode have always been the pursuit of analysis from generation to generation. Recently, chemical sensing based on ZnO materials have attracted a great interest in the applications of biosensors due to their remarkable properties like non- toxic, bio-safety, excellent biological compatibility, high- electron transfer rates, enhanced analytical performance, increased sensitivity, easy fabrication and low cost. In P. Pattanaik Á D. K. Mishra Á J. Mohapatra Á S. K. Kamilla (&) Centre for Nanoscience and Nanotechnology, Institute of Technical Education and Research, Siksha ‘O’ Anusandhan University, Khandagiri Square, Bhubaneswar 751030, Odisha, India e-mail: sushantakamilla@soauniversity.ac.in D. K. Mishra Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, South Africa E. Subudhi Centre for Bio-Technology, Siksha ‘O’ Anusandhan University, Khandagiri Square, Bhubaneswar 751030, Odisha, India D. P. Das CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751013, Odisha, India 123 J Mater Sci: Mater Electron (2015) 26:992–997 DOI 10.1007/s10854-014-2494-x