RESEARCH ARTICLES CURRENT SCIENCE, VOL. 109, NO. 8, 25 OCTOBER 2015 1427 *For correspondence. (e-mail: kalyan700@gmail.com) Electrochemical characterization of some commercial screen-printed electrodes in different redox substrates Kalyan Kumar Mistry 1,2, *, Sagarika Deepthy, T. 1 , Chirasree Roy Chaudhuri 2 and Hiranmay Saha 3 1 CSIR-Central Mechanical Engineering Research Institute, M.G. Avenue, Durgapur 713 209, India 2 Department of Electronics and Telecommunication Engineering and 3 Centre of Excellence for Green Energy and Sensor System, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711 103, India Electrochemical sensors based on screen-printed elec- trodes (SPEs) are applied for the precise detection of an analyte concentration in a sample solution and is one of the thrust areas of research, especially in healthcare and environmental monitoring. In this arti- cle we report electrochemical characterization of some commercially available SPEs obtained from three dif- ferent commercial manufacturers in three different re- dox probes such as potassium ferricyanide, ascorbic acid/vitamin-C and nicotinamide adenine dinucleotide. The main aim of this study is to compare the sensitivity, stability, ideality and reproducibility in the develop- ment of electrochemical sensors for specific detection of biological or chemical substances using SPEs. Keywords: Electrochemical characterization, environ- mental monitoring, healthcare, redox probe, screen- printed electrode. ELECTROCHEMICAL sensors based on screen-printed elec- trodes (SPEs) are convenient to use because of their ease of fabrication, ability to mass produce and low cost 1–3 . Surface of SPEs can be easily modified by immobiliza- tion of different biomolecules, enzymes and catalytic substances and thus can be tuned to enhance the sensiti- vity and selectivity of detection. The other important advantage of using SPEs is the requirement of minimal volume of analyte solutions which is cost effective and particularly useful when sample volume is minute 4 . SPE consists of three electrodes, namely working elec- trode (WE), reference electrode (RE) and auxiliary or counter electrode (AE) printed using conductive ink ma- terial on a solid substrate in planar form. WE is the main sensing platform mostly made of carbon and its compo- sites. When a small volume of analyte sample solution is dispensed using a pipette on the electrode surface, it forms an electrochemical cell system and produces elec- trical signal at an applied control potential which corre- sponds to the analyte concentration. Commonly used electrochemical characterization technique is the current– voltage (CV) characteristics plot of the electrochemical cell system. When controlled potential is applied between RE and WE, current flows through AE and WE and it is measured by a potentiostat. Measurement of current ampli- tude at either reduction or oxidation potential, maintaining the current peak at a stable defined condition corresponds to detecting the precise concentration of the specific ana- lyte, even ng/ml to a few fg/mL (femtograms/mL). Electrode fabrication based on screen printing is based on thick film technology; it originated 3000 years ago and can be traced in the construction of the Great Wall of China as well as in ancient Egyptian cloth patterns 4,5 . SPE is an integrated electrically conducting layer and it is fabricated on a chemically inert insulating solid plate or film made of various materials such as ceramic 6–9 , plas- tic 10–12 , glass 13 , flexible polyester film 14–16 , etc. using the screen printing technique. SPEs are mostly disposable in nature. Several studies have been made on the develop- ment of electrochemical and biological sensing based on SPE using various methods of electrode surface function- alization and surface modification for specific applica- tions 17–19 . Studies have reported that the electrode design parameters such as shape, geometric dimensions and spacing affect the performance of SPEs. Studies also highlight the effect of electrode material, particularly WE on the electrochemical performance of SPEs. WE is typically made of carbon ink and many lit- erature reports discuss various factors like carbon ink formulation, ink composition and particle size to affect the performance of these SPEs. But these being proprie- tary informations, the exact nature and composition of the electrode material cannot be deciphered 20,21 . The sensing platform of SPE not only depends upon the property of ink material, but also on the printing process, loading, curing temperature, etc. Carbon surface structure, mor- phology and surface orientation play an important role in electron transfer at the interface of the electrode surface and electrolyte solution.