A Flexible, Highly Sensitive, and Selective Chemiresistive Gas Sensor Obtained by In Situ Photopolymerization of an Acrylic Resin in the Presence of MWCNTs

AbstractA new flexible polymeric gas sensor is developed by photocrosslinking poly(ethylene glycol) diacrylate resin (PEGDA) containing multi‐walled carbon nanotubes (MWCNTs) as conductive filler. The cured material shows a percolative threshold conductivity which changes when in contact with various gas analytes with different chemical and physical properties. The different behavior of the sensors toward the different gases is explained either on the basis of chemical affinity toward the polymeric matrix or due to the interactions that can occur between the analyte and the surface of the nanotubes in the case of the aromatic gas

Graphene-based composite with high stable dispersion in ethanol.

In the last few years a lot of applicative research studies are focused on graphene, a 2D carbo-material with very particular physical features like electro-conductivity, thermo-conductivity, mechanical stability, and its particular aspect ratio with a high surface and a negligible thickness (1–3). For that features the spectra of possibilities to make a new application with this material, are big and grow time after time. In addition, with climate change, the focus of research to make new technologies greener and with less impact, on the environment, than now has moved to increase the study of that material and most researchers have focused their studies on the possibility to disperse that material in a green solvent with low boiling point. One problem with pristine Graphene is that it could be dispersed with high concentration only in polar aprotic solvent as n-methyl-2-pyrrolidone or Dimethyl formamide (4), a solvent with a high boiling point and with high toxicity for the humans and the environment. Usually for that reason is preferred to use the oxidized form of graphene GO, most easy to disperse, and reduce in rGO. The reduced form has the problem of having more defects on the surface than pristine graphene losing a part of the natural performance of the graphene. Another method studied is the use of a surfactant (5)or making nano-composite material with the use of polar polymer such as the PVP (6–8) has permitted to disperse of the material with a good concentration in water. This research has moved used to investigate how to make new composite graphene-based, easy to disperse in an organic polar solvent such as ethanol. We made an uncontrolled growth of polymer (ethyl maleate derivate) on the surface of the material, for making that we use the support of the microwave reactor that, with the particular characteristic of the graphene to be a radical initiator, permits the formation of different particles of polymer maleate based on the surface of the graphene. This material has good stability in ethanol and maintains that feature after a long time. That dispersion opens the possibility to make ink graphene-based or coating on other surfaces and other different applications with the fast removal of the solvent. At the same time the uncontrolled growing permit the removal of the composite with the heating of the material in an inert atmosphere to obtain pristine graphene with a low number of defects. Bibliography 1. Clancy AJ, Bayazit MK, Hodge SA, Skipper NT, Howard CA, Shaffer MSP. Charged Carbon Nanomaterials: Redox Chemistries of Fullerenes, Carbon Nanotubes, and Graphenes. Chem Rev. 2018;118(16):7363-7408. doi:10.1021/acs.chemrev.8b00128 2. Randviir EP, Brownson DAC, Banks CE. A decade of graphene research: Production, applications, and outlook. Mater Today. 2014;17(9):426-432. doi:10.1016/j.mattod.2014.06.001 3. Wei W, Qu X. Extraordinary physical properties of functionalized graphene. Small. 2012;8(14):2138-2151. doi:10.1002/smll.201200104 4. Vacacela Gomez C, Guevara M, Tene T, et al. The liquid exfoliation of graphene in polar solvents. Appl Surf Sci. 2021;546(December 2020):149046. doi:10.1016/j.apsusc.2021.149046 5. Wang S, Yi M, Shen Z, Zhang X, Ma S. Adding ethanol can effectively enhance the graphene concentration in water-surfactant solutions. RSC Adv. 2014;4(48):25374-25378. doi:10.1039/c4ra03345k 6. Laaksonen P, Kainlauri M, Laaksonen T, et al. Interfacial engineering by proteins: Exfoliation and functionalization of graphene by hydrophobins. Angew Chemie - Int Ed. 2010;49(29):4946-4949. doi:10.1002/anie.201001806 7. Perumal S, Lee HM, Cheong IW. High-concentration graphene dispersion stabilized by block copolymers in ethanol. J Colloid Interface Sci. 2017;497:359-367. doi:10.1016/j.jcis.2017.03.027 8. Wajid AS, Das S, Irin F, et al. Polymer-stabilized graphene dispersions at high concentrations in organic solvents for composite production. Carbon N Y. 2012;50(2):526-534. doi:10.1016/j.carbon.2011.09.00

Rigid tool affordance matching points of regard

In this abstract we briefly introduce the analysis of simple rigid object affordance by experimentally establishing the relation between the point of regard of subjects before grasping an object and the finger tip points of contact once the object is grasped. The analysis show that there is a strong relation between these data, in so justifying the hypothesis that people figures out how objects are afforded according to their functionality

SELF-HEALING HYDROGELS 3D-PRINTED VIA VAT PHOTOPOLYMERIZATION

virtual European Symposium of Photopolymer Science 202

Electrospun PEO/PEDOT:PSS Nanofibers for Wearable Physiological Flex Sensors

Flexible sensors are fundamental devices for human body monitoring. The mechanical strain and physiological parameters coupled sensing have attracted increasing interest in this field. However, integration of different sensors in one platform usually involves complex fabrication process-flows. Simplification, even if essential, remains a challenge. Here, we investigate a piezoresistive and electrochemical active electrospun nanofibers (NFs) mat as the sensitive element of the wearable physiological flex sensing platform. The use of one material sensitive to the two kinds of stimuli reduces the process-flow to two steps. We demonstrate that the final NFs pH-Flex Sensor can be used to monitor the deformation of a human body joint as well as the pH of the skin. A unique approach has been selected for pH sensing, based on Electrochemical Impedance Spectroscopy (EIS). A linear dependence of the both the double layer capacitance and charge transfer re-sistance with the pH value was obtained by EIS, as well as a linear trend of the electrical resistance with the bending deformation. Gauge factors values calculated after the bending test were 45.84 in traction and 208.55 in compression mode, reflecting the extraordinary piezoresistive behavior of our nanostructured NFs

Determination of reliable resistance values for electrical double-layer capacitors

The power capabilities of supercapacitors are strongly influenced by their passive elements. Within this study, we investigate methods to address resistive components out of galvanostatic measurements and we compared literature methods with the aim to provide a guide to correctly exploit the resistance of supercapacitors. The impact of the sampling conditions of galvanostatic measurements is analyzed and related to electrochemical impedance spectroscopy. Further, a novel method based on the instantaneous power analysis is provided to get real-time information concerning the actual cell resistance during the measurement without altering the gal- vanostatic experiment. Measurements show that literature methods can provide values close to the series resistance, while the newly proposed power method results in a good estimate of the actual dissipative value

Bayesian non-parametric inference for manifold based MoCap representation

We propose a novel approach to human action recognition, with motion capture data (MoCap), based on grouping sub-body parts. By representing configurations of actions as manifolds, joint positions are mapped on a subspace via principal geodesic analysis. The reduced space is still highly informative and allows for classification based on a non-parametric Bayesian approach, generating behaviors for each sub-body part. Having partitioned the set of joints, poses relative to a sub-body part are exchangeable, given a specified prior and can elicit, in principle, infinite behaviors. The generation of these behaviors is specified by a Dirichlet process mixture. We show with several experiments that the recognition gives very promising results, outperforming methods requiring temporal alignment

Component-wise modeling of articulated objects

We introduce a novel framework for modeling articulated objects based on the aspects of their components. By decomposing the object into components, we divide the problem in smaller modeling tasks. After obtaining 3D models for each component aspect by employing a shape deformation paradigm, we merge them together, forming the object components. The final model is obtained by assembling the components using an optimization scheme which fits the respective 3D models to the corresponding apparent contours in a reference pose. The results suggest that our approach can produce realistic 3D models of articulated objects in reasonable time

Design and Optimization of Piezoresistive PEO/PEDOT:PSS Electrospun Nanofibers for Wearable Flex Sensors

Flexible strain sensors are fundamental devices for application in human body monitoring in areas ranging from health care to soft robotics. Stretchable piezoelectric strain sensors received an ever-increasing interest to design novel, robust and low-cost sensing units for these sensors, with intrinsically conductive polymers (ICPs) as leading materials. We investigated a sensitive element based on crosslinked electrospun nanofibers (NFs) directly collected and thermal treated on a flexible and biocompatible substrate of polydimethylsiloxane (PDMS). The nanostructured active layer based on a blend of poly(ethylene oxide) (PEO) and poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) as the ICP was optimized, especially in terms of the thermal treatment that promotes electrical conductivity through crosslinking of PEO and PSS, preserving the nanostructuration and optimizing the coupling between the sensitive layer and the substrate. We demonstrate that excellent properties can be obtained thanks to the nanostructured active materials. We analyzed the piezoresistive response of the sensor in both compression and traction modes, obtaining an increase in the electrical resistance up to 90%. The Gauge Factors (GFs) reflected the extraordinary piezoresistive behavior observed: 45.84 in traction and 208.55 in compression mode, which is much higher than the results presented in the literature for non-nanostructurated PEDOT

Electrostimulation of a 3D in vitro skin model to activate wound healing

The aim of the work is to propose a methodology for the stimulation of a 3D in vitro skin model to activate wound healing. The presented work is in the frame of the national research project, CronXCov, “Checking the CHRONIC to prevent COVID-19”, devoted to understand how physiologic and inflamed skin on chip 3D models evolve upon a range of physical (e.g., electrical, mechanical, optical) stimulations, over time. Thanks to the 3D modelling, using Next Generation Sequencing and the network medicine frame of analysis to process the data, we will systematically characterize the effects of the applied stimuli, offering new insight for the exploitation of wound healing