https://hdl.handle.net/20.500.12008/37 2026-09-17T17:31:57Z https://hdl.handle.net/20.500.12008/56674 Título: Revealing microscale hydrogel 3d structural features at ambient conditions using ptychographic X-ray computed tomography Autor: Gregorio, Tatiana; Kalile, Tiago A.; Meneau, Florian; Liu, Chunzhao; Wang, Xiaoyu; Gao, Chao; Fu, Shunli; Mombrú, Dominique; Romero, Mariano; Mombrú, Álvaro W. Resumen: Hydrogels and microscale hydrogels containing micron-scale pores are extensively utilized in diverse fields because of their superior mass transport properties, large surface area, and strong resemblance to biological tissues, making them especially valuable in biomedical applications and devices. For this reason, accurately characterizing their porosity and pore interconnectivity under realistic ambient conditions rather than the vacuum environments often used in conventional studies is essential. In this work, the nano- and microstructural features of hydrogels are investigated using ptychographic X-ray computed tomography (PXCT), achieving a spatial resolution of 127 nm and covering a field of view of approximately 100 × 30 μm2 under ambient conditions. The hydrogel microscopic samples exhibited a modification of the bulk pore size (from ∼0.9 μm) and porosity (from ∼20%) with decreasing thickness (toward ∼0.7 μm and 5%, respectively) and with increasing departure from the bulk region (toward ∼1.2 μm and 30%, respectively). Furthermore, pore throat sizes are estimated to fall mainly below ∼200 nm for narrower connections and 400−500 nm for wider ones. Notably, pore connectivity and thus transport efficiency is greater in the out-ofplane direction than in-plane. These findings are critical for understanding transport behavior and performance in real biological environments. Descripción: Manuscrito enviado de la versión final publicada. 2026-01-01T00:00:00Z https://hdl.handle.net/20.500.12008/56662 Título: The indirect sensing of alkali metal counterions using P3HT-based organic electrochemical transistors working in the accumulation mode Autor: Gregorio, Tatiana; Mombrú, Dominique; Romero, Mariano; Mombrú, Álvaro W. Resumen: Here, we report the alkali metal counterion effect and its corresponding indirect sensing using poly(3- hexylthiophene)-based organic electrochemical transistor (OECT) devices working in the accumulation mode with bis(trifluoromethanesulfonyl)imidate salt aqueous solution as electrolyte. Our in-operando microRaman imaging studies confirmed that the charge transport and transfer processes are associated with the accumulation mode configuration, while our in-operando Xray scattering studies indicate that the injection of dopants reached not only the swollen amorphous but also the crystalline regions of poly(3-hexylthiophene) (P3HT). Interestingly, we have observed characteristic features depending on the alkali metal counterion in both the output and transfer characteristics for these OECT devices. The channel current/transconductance exhibited a progressive increase, while the threshold voltage exhibited a progressive decrease in the OECT response with increasing the alkali metal ionic size. For instance, for OECT with W/L = 500/20 geometries, the maximum transconductance values were gmax = 11.9, 14.1, and 22.3 mS, the threshold voltage values were -Vth = 0.31, 0.27, and 0.20 V, and the figure of merit values were μC* = 3.51, 4.81, and 7.31 F·cm−1·V−1·s−1, for LiTFSI, NaTFSI, and KTFSI 0.1 M, respectively. In addition, the OECT response yielded excellent sensitivity for alkali metal counterions using secondary electrolytes such as LiCl, NaCl, and KCl in a broad range of concentrations from 10 to 1000 mM. We evidence that these P3HT-based OECT devices can be extremely useful to determinate Li+, Na+, and K+ working in the accumulation mode exhibiting sensitivities ranging from Δ(−Ids) = −0.3 to −1.3 mA, −0.6 to −2.2 mA, and −2.3 to −4.5 mA in the case of Li+, Na+, and K+, respectively. This indicates that the cation expulsion mechanism can be used for the indirect sensing of alkali metal ions in P3HT-based OECT devices working in the accumulation mode, yielding excellent response compared with those typically observed for PEDOT:PSS-based OECT devices working in the depletion mode. 2025-01-01T00:00:00Z https://hdl.handle.net/20.500.12008/56643 Título: The effect of critical micelle concentration on the amphiphilic species response using P3HT- based organic electrochemical transistors Autor: Gregorio, Tatiana; Miraballes, Iris; Mombrú, Dominique; Romero, Mariano; Mombrú, Álvaro W. Resumen: Here, we present a proof-of-concept approach to study the effect of critical micelle concentration on alkyl sulfonate amphiphilic species response using organic electrochemical transistors (OECT) working in the accumulation mode. First of all, the drastic enhancement of the OECT response allows us to estimate the critical micelle concentration of alkyl sulfonate amphiphilic species yielding quite similar values compared to bulk solution conductivity experiments reported in the literature. Above the critical micelle concentration (i.e. 100 mM), the best responsive OECT devices yielded ON/OFF ratios of 30–60, maximum normalized transconductance of g max ¼ 1:99 1:39 mS cm 1 and threshold voltage of Vth = 0.39–0.55 V at Vg = 1.0 V. Our impedance spectroscopy studies performed at ON and OFF modes suggested that, in the presence of a sufficiently strong negative gate voltage (Vg = 1.0 V), not only the sodium counterions are ejected from the interface, but also the amphiphilic molecules from the monolayer probably reverse their orientation and get injected into the P3HT region. In this scenario, the sulfonate groups of the amphiphilic species synchronously induce doping of P3HT thus leading to a drastic enhancement of the channel current above the critical micelle concentration. Our results indicate that OECT devices represent a promising platform to estimate the critical micelle concentration of amphiphilic species but also to study the formation of amphiphilic monolayers of more complex systems of biological interest. Descripción: Manuscrito enviado de la versión final publicada. 2025-01-01T00:00:00Z https://hdl.handle.net/20.500.12008/56471 Título: Impact of warning labels on energy drink perceptions and purchase intentions among emerging adults in Uruguay Autor: Antúnez, Lucía; Gaites, Milene; Giacummo, Sofía; Villalba, Juan; Varela, Leticia; Machín, Leandro; Ares, Gastón Resumen: Background: The rapid expansion of energy drink markets over the past two decades has sparked growing policy debate surrounding their regulation, due to their potential adverse health effects, particularly among young people. In this context, mandatory warning labels have emerged as a promising public health intervention. The present work aims to explore the effect of warning labels on emerging adults’ purchase intention and perceived healthfulness of energy drinks in Uruguay. Methods: An online randomized controlled trial was implemented using a convenience sample of 340 emerging adults. Commercial energy drink cans, varying in brand (market-leading vs. lesser-known brand) and sugar content (regular vs. zero-added sugar variant), were used as stimuli. Participants were randomly assigned to either the control group (no warning label) orone of the four intervention groups, each of which was exposed to a warning label condition (Insomnia-graphic, Insomnia-textual, Tachycardia-graphic, Tachycardia-textual). The questionnaire comprised six main sections: (i) purchase intention; (ii) perceived effects of energy drink consumption and perceived healthfulness; (iii) perception of warning labels; (iv) comparison of warning labels; (v) socio-demographic characteristics; and (vi) energy drink consumption habits and perceived risk. Results: The graphic warning referring to tachycardia led to a significant reduction in purchase intention and perceived healthfulness compared with the control condition; no significant effect was observed for the remaining warning label conditions. In addition, warning labels were consistently associated with an increased attribution of the negative effects they highlighted, whereas no statistically significant effects on positive outcomes were observed. Results also provide emerging insights into the role of branding, consumption patterns and risk perception in shaping perceived healthfulness and purchase intention for energy drinks. Regarding participants’ perception of warning labels, the graphic tachycardia warning emerged as the most effective condition. Conclusions: Results support the use of warning labels as a public health strategy to increase awareness of the potential harms associated with energy drink consumption and suggest that their impact may extend even to products with strong market presence and high consumer recognition. 2026-01-01T00:00:00Z