Piezo-Phototronic In2Se3 Nanosheets as a Material Platform for Printable Electronics toward Multifunctional Sensing Applications


By Christos Polyzoidis, Konstantinos Rogdakis, George Veisakis, Dimitris Tsikritzis, Payam Hashemi, Hyejung Yang, Zdeněk Sofer, Ali Shaygan Nia, Xinliang Feng, Emmanuel Kymakis

EMERGE participant (1st Call):  Bing Wu

Joint research activity between Hellenic Mediterranean University and Technische Universität Dresden

Published date: 28-06-2023

A facile, ultralow-cost, and up-scalable printable manufacturing process of flexible, multifunctional sensors that respond to more than one external stimulus could have a pivotal role in low-cost wearables and portable systems for Industry 4.0. Herein, using a low capex, in-house spray coating system, the fabrication of a low-cost photodetector that is tuneable by mechanical strain exploiting the piezo-phototronic nature of defect-free 2D In2Se3 nanosheets is reported. Moreover, force sensors that respond to different levels of applied force are spray-coated by using In2Se3 nanosheets. Regarding the photodetector, a nonmonotonic and asymmetric effect of strain on photocurrent response is shown exhibiting a local maximum at the 23°–32° compressive angle range and a slight hysteresis. Forward compressive bending leads to a photocurrent enhancement by 27% at 32° and reverse by 31% at 23°, while tensile strain leads to a current suppression by 8–10% at 23°–32° angle. The resulting force sensor repeatably demonstrates discrete piezoelectric voltages in the millivolt scale upon different mass loads, opening the path for force and tactile sensing applications. Applying industrially compatible materials for the underlying flexible substrate and electrodes, combined with spray coating, removes manufacturing complexities that engage costly and energy intensive fabrication.

Mechanochemical Synthesis of TiO2-CeO2 Mixed Oxides Utilized as a Screen-Printed Sensing Material for Oxygen Sensor


By Jelena N. Stevanović, Srđan P. Petrović, Nenad B. Tadić, Katarina Cvetanović, Ana G. Silva, Dana Vasiljević Radović and Milija Sarajlić

EMERGE participant (1st Call):  Milija Sarajlić

Published date: 24-01-2023

TiO2 and CeO2 are well known as oxygen sensing materials. Despite high sensitivity, the actual utilization of these materials in gas detection remains limited. Research conducted over the last two decades has revealed synergistic effects of TiO2-CeO2 mixed oxides that have the potential to improve some aspects of oxygen monitoring. However, there are no studies on the sensing properties of the TiO2-CeO2 obtained by mechanochemical treatment. We have tested the applicability of the mechanochemically treated TiO2-CeO2 for oxygen detection and presented the results in this study. The sensing layers are prepared as a porous structure by screen printing a thick film on a commercial substrate. The obtained structures were exposed to various O2 concentrations. The results of electrical measurements showed that TiO2-CeO2 films have a significantly lower resistance than pure oxide films. Mixtures of composition TiO2:CeO2 = 0.8:0.2, ground for 100 min, have the lowest electrical resistance among the tested materials. Mixtures of composition TiO2:CeO2 = 0.5:0.5 and ground for 100 min proved to be the most sensitive. The operating temperature can be as low as 320 °C, which places this sensor in the class of semiconductor sensors working at relatively lower temperatures.