Celebrating Electrochemical Sensors at the 2017 Matrafured Meeting


Celebrating Electrochemical Sensors at the 2017 Matrafured Meetingpubs.acs.org/doi/pdfplus/10.1021/acssensors.7b00452by...

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Celebrating Electrochemical Sensors at the 2017 Matrafured Meeting

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assess the quality of the transducing layer. Lindner argued that this test is only meaningful if the interfering ions are actually capable of exchanging quantitatively with the ion of interest, and that the test should be performed with sensor membranes of modest selectivity. I described a simple voltammetric method involving very thin solid contact ion-selective membranes to quantitatively extract all thermodynamic parameters relevant to sensing: complex formation constants, binding stoichiometry, and selectivity. Bobacka used solid contact ion-selective membranes held at a fixed potential to give a short current spike upon concentration change. The spike reflects the capacitive adjustment of the inner boundary potential to compensate for the change at the sample side of the membrane. Such coulometric sensors appear to be very sensitive, and might be used to detect very small concentration changes. Citterio presented elegant work on the ink jet printing of solid state potentiometric sensors on paper for potential mass production, with excellent results. The Matrafured conference was started 45 years ago by Erno Pungor (Hungary) and Wilhelm Simon (Switzerland), in an effort to bring together scientists of the former East and West and working in the field of ion-selective electrodes, at a time when arguments about the prevalent working mechanism were very spirited. Such open and critical discussions continue to this day, but the meetingorganized today jointly by Philippe Bühlmann, Robert Gyurscanyi, Erno Pretsch, Joseph Wang, and myselfhas since broadened its scope to welcome people from all fields of electrochemical (and optical) sensor science. Let us mark our calendars for the next event in 2020, and thank ACS Sensors, along with the other many sponsors, for supporting this stimulating meeting.

his past June, electrochemical sensor scientists converged at the Matrafured Meeting in Visegrad, Hungary. This meeting, which is held every three years, shows so well why we love this field: Thoughtful, critical scientists, from 27 nations, coming together to share their knowledge, welcome the young, connect to industry, and embrace interdisciplinary and translational work. The week-long affordable, single session meeting involved a daily after-dinner poster session, giving rise to stimulating discussions, and the opportunity to make new contacts and to renew existing ones. The conference banquet was combined with an excursion in the form of a visit to the fisherman’s bastion in Budapest, followed by a leisurely dinner cruise on the Danube. There were 156 participants from the fields of ion-selective electrodes, molecularly imprinted materials, aptamer- and other DNA-based sensors, nanopores, enzyme biosensors and enzyme engineering, optodes, scanning probes, magnetic nanoparticle-based sensors, field effect transistors, reference electrodes, paper-based sensors, and ion transfer voltammetry. At the same time, the conferees were exposed to medical advice on making sensors that matter: Pendley emphasized that a test must be diagnostically useful, and that there are cases where the anticipated sensing error must be essentially zero to make any medical sense at all, which might be impossible to achieve. Environmental questions important to sensing were also discussed, mainly in the form of reducing interferences and improving robustness, as presented in separate talks by Revsbech and Cuartero. The challenge of chemical sensor science lies in many ways in the fact that any elegant idea, material, or approach must be tested against a demanding real-world problem. The issues of nonspecific adsorption on sensor surfaces, and of matrix effects in general, were therefore prevalent discussion points. Scheller, for example, emphasized how surface imprinting is a very promising technique for molecular recognition, but that the underlying exposed electrode surface will still suffer from nonspecific adsorption. Many talks gave surprising findings, sensitivities that could not be readily explained, and pointed out an excellent inherent sensitivity of a technique, but where it is difficult to relate to the sample concentration. How does the analyte find the sensor if there are just a few molecules around? Mirkin observed extremely low detection limits for dopamine detection with electrochemical nanocavity probes, but acknowledged that the findings are currently not explainable. Gooding, on the other hand, advocated the harvesting of analytes with functionalized magnetic beads that subsequently act as the electrode surface, but was surprised that it worked so well at such low concentrations. Fundamental discussions also involved how materials are best characterized, as amply discussed with buried ion-toelectron transducing layers for the realization of all solid state potentiometric sensing probes. For example, the so-called water layer test involves the monitoring of the potential−time trace after exposure to a solution containing only interfering ions to © 2017 American Chemical Society

Eric Bakker, Associate Editor



The University of Geneva, Geneva, Switzerland

AUTHOR INFORMATION

ORCID

Eric Bakker: 0000-0001-8970-4343 Notes

Views expressed in this editorial are those of the author and not necessarily the views of the ACS.

Received: July 4, 2017 Published: July 28, 2017 854

DOI: 10.1021/acssensors.7b00452 ACS Sens. 2017, 2, 854−854