A. Lesch, M. Jović, F. Gumy, H.H. Girault
EPFL Valais Wallis,
Keywords: inkjet printed sensors, antioxidants detection, environmental sensing, pH measurements
Summary:Medical diagnostics for the determination and monitoring of the health condition of patients, sportsmen but also normal persons represents an important market with increasing opportunities for sensor platform development, production and applications. For instance, amperometric electrode chips allow the rapid, simple and low cost detection of specific analytes in biological fluids such as blood and saliva, but also in environmental systems including tap and lake waters. The measurements are based on recording electrochemical signals at the pre- or non-pretreated sample-electrode interface. For accurate and reliable measurements electrode materials of high reproducibility, purity and activity are required. This becomes challenging, in particular for complex sample matrices, where electrode fouling, high overpotentials of targeted analytes and interferences between various electrochemically active species play a role. In addition, substrates have often to be diluted and statistically relevant repetitions of measurements are essential to verify the observed trends. Furthermore, reliable measurements require usually the disposable use of a large number of electrodes. In order to provide the most suitable platform for each specific application, electrode chip manufacturers face constantly many of the mentioned challenges. Inkjet printing as a digital material deposition technique has shown its potential for the production of many types of devices including photovoltatics and transistors thanks to the flexibility of designing the patterns, inks and printing processes. Herein, we demonstrate the successful implementation of the inkjet printing technology for the large scale production of various single and multiplexed electrode platforms that are dedicated to measure for instance the antioxidant content in blood, the pH, as well as the concentration of herbicides and contaminants in water samples. We show the successful chain from the prototype development to the final product of fully inkjet printed, disposable electrode chips. Based on the electrochemical properties, various commercial and self-made inks, including carbon nanotubes, silver, gold and platinum were employed on an inkjet printing device comprised of three parallel printheads with integrated post processing stations for UV photopolymerization and photonic curing. Finally, we demonstrate how inkjet printing can be successfully used to coat electrode surfaces with nanometer thin layers of hydrogels, which as a result brings new functionalities for the sensing of hydrophilic antioxidants. References:  A. Lesch, F. Cortés-Salazar, M. Prudent, J. Delobel, S. Rastgar, N. Lion, J.-D. Tissot, P. Tacchini, H. H. Girault, J. Electroanal. Chem. 2014, 61, 717-718.  A. Lesch, F. Cortés-Salazar, V. Amstutz, P. Tacchini, H. H. Girault, Anal. Chem. 2015, 87, 1026– 1033.  M. Jović, F. Cortés-Salazar, A. Lesch, V. Amstutz, H. Bi, H. H. Girault, J. Electroanal. Chem. 2015, 756, 171–178.