Ultra-conformal drawn-on-skin electronics for multifunctional motion artifact-free sensing and point-of-care treatment

An accurate extraction of physiological and physical signals from human skin is crucial for health monitoring, disease prevention, and treatment. Recent advances in wearable bioelectronics directly embedded to the epidermal surface are a promising solution for future epidermal sensing. However, the existing wearable bioelectronics are susceptible to motion artifacts as they lack proper adhesion and conformal interfacing with the skin during motion. Here, we present ultra-conformal, customizable, and deformable drawn-on-skin electronics, which is robust to motion due to strong adhesion and ultra-conformality of the electronic inks drawn directly on skin. Electronic inks, including conductors, semiconductors, and dielectrics, are drawn on-demand in a freeform manner to develop devices, such as transistors, strain sensors, temperature sensors, heaters, skin hydration sensors, and electrophysiological sensors. Electrophysiological signal monitoring during motion shows drawn-on-skin electronics' immunity to motion artifacts. Additionally, electrical stimulation based on drawn-on-skin electronics demonstrates accelerated healing of skin wounds. Designing efficient wearable bioelectronics for health monitoring, disease prevention, and treatment, remains a challenge. Here, the authors demonstrate an ultra-conformal, customizable and deformable drawn-on-skin electronics which is robust to motion artifacts and resistant to physical damage

Investigation of cell-level potential-induced degradation mechanisms on perovskite, dye-sensitized and organic photovoltaics

The study focuses on the effect of bias voltage degradation or Potential Induced Degradation (PID) on the efficiency of perovskite (PSCs), dye-sensitized (DSSCs) and organic (OPVs) solar cells. For the PID study, voltage-depended and time-depended degradation tests have been carried out at solar cell level; the cells were fabricated and tested in the same conditions. Furthermore, the solar cells were exposed to both, annealing and cooling tests in order tp highlight the various PID characteristics. Thus, the mechanisms induced during the PID degradation were thoroughly investigated. Results revealed that DSSCs are far more vulnerable to voltage degradation than other solar cell technologies. The current work illustrates that OPV solar cells can be considered as voltage durable compared to PSCs and DSSCs ones. OPV solar cells lost 23% of their initial efficiency whereas PSC and DSSC cells were entirely degraded after the application of 5.5 V and 2.5 V voltage respectively. Furthermore, in contrast to OPV, DSSCs and PSCs did not exhibit charging effect when a 5 V voltage was applied. © 2019 International Solar Energy Societ

Atomic-scale understanding of dichlorobenzene-assisted poly 3-hexylthiophene-2,5-diyl nanowire formation mechanism

WOS: 000394919100077Low-dimensional Poly 3-hexylthiophene-2,5-diyl (P3HT) structures that serve efficient exciton dissociation in organic solar cells, play a major role in increasing the charge collection, and hence, the efficiency of organic devices. In this study, we theoretically and experimentally investigate the Dichlorobenzene (DCB)-assisted formation of P3HT nanowires. Our experiments show that the solution of DCB molecules drive randomly oriented P3HT polymers to form well-stacked nanowires by stabilizing tail-tail and pi-pi interactions. Here the question is how DCB molecules migrate into the P3HT layers while forming the nanowire structure. Our density functional theory-based calculations reveal that the vertical migration of the DCB molecules between P3HT layers is forbidden due to a high energy barrier that stems from strong alkyl chain-DCB interaction. In contrast to vertical diffusion, lateral diffusion of DCB molecules in between P3HT layers is much more likely. Our results show that migration of a DCB molecule occurs through the alkyl groups with a low energy barrier. Therefore, laterally diffused DCB molecules assist nucleation of top-to-top stacking of P3HT polymers and formation of well-ordered nanowires. (C) 2017 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [116C073]; Bilim Akademisi - The Science Academy, Turkey under the BAGEP programComputational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). H.S. acknowledges financial support from the Scientific and Technological Research Council of Turkey (TUBITAK) under the project number 116C073. H.S. acknowledges support from Bilim Akademisi - The Science Academy, Turkey under the BAGEP program

The stock market rumours and stock prices: a test of price pressure and size effect in an emerging market

The purpose of this study is to investigate the effects of stock market rumours/gossips on the prices of stocks traded at the Istanbul Stock Exchange with respect to price pressure and size effect. While positive significant abnormal returns are observed in days prior to the publication date, negative insignificant abnormal returns are detected in post-publication period. The view that the price movement is due to the price pressure created by the column itself is not supported. Furthermore, the smaller firms appears to be more speculative and negative returns in post publication period is more pronounced. The findings in pre-publication period refute the strong form of market efficiency while the findings in post-publication period suggest that investment decisions based on the published rumours would not benefit investors.