Compact polyelectrolyte hydrogels of gelatin and chondroitin sulfate as ion's mobile media in sustainable all-solid state electrochemical devices

The creation of flexible and high strength hydrogel materials from natural polymers aslow cost and safe solid electrolytes is an area of intense research nowadays. We presenta novel approach for the preparation of gelatin and chondroitin sulfate hydrogelscomplexes by using a simple centrifugation process. The innovative dual-bio-gelnetworkis able to swell and shrink upon environmental changes on the pH and NaClconcentration. The solid bio-gels sandwiched between two macroporous carbonelectrodes materials are assembled in symmetric cells and their electrochemicalproperties are evaluated by cyclic voltammetry, galvanostatic, and impedancespectroscopy. The cells exhibit areal capacitance values by up to 2.74 mF/cm2 (3.1 F/g)and a low resistance value of 12 Ohm.cm2 for graphene electrode materials. Theseproperties are the consequence of the successful infiltration of the solid gel inside theporous structure of the carbon electrode that boosts the charge transfer at thebiopolymer/carbon electrode interphase. The results obtained may provide additionalinspiration in the emerging field of bioelectronics, where biocompatible and poweredsystems are of the utmost importance.Fil: Gonzalez, Jimena Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Consejo Superior de Investigaciones Científicas; EspañaFil: Burlaka, Arsen. Consejo Superior de Investigaciones Científicas; EspañaFil: Paz, José. Consejo Superior de Investigaciones Científicas; EspañaFil: Salavagione, Horacio. Consejo Superior de Investigaciones Científicas; EspañaFil: Carretero González, Javier. Consejo Superior de Investigaciones Científicas; EspañaFil: Hernández, Rebeca. Consejo Superior de Investigaciones Científicas; Españ

The effect of conformational transition of gelatin-polysaccharide polyelectrolyte complex on its functional properties

The blends of gelatin and shear-thinning hydrocolloids (guar gum, kappa-carrageenan and xanthan gum) were examined to determine the effect of the conformational change on the functional properties of the solutions. The polyelectrolyte complexes of 0.5% gelatin/0.5% polysaccharide in 70 mM KCl or 70 mM NaCl were investigated by the laboratory rheometer and conductivity meter in the temperature range 25 - 45 °C. The rheological data were fitted by the power-law and Herschel-Bulkley model to obtain the flow parameters. The functional properties of the samples were substantially affected by the conformational change of the polysaccharide, as well as by the type of the hydrocolloid and salt solution. There was an evident change of viscosity and conductivity of the solutions upon heating, corresponding to the helix-coil transition of the polysaccharide at temperature about 35 °C. The type of the salt solvent had an effect on the gelation properties of the samples. Gelatin/kappa-carrageenan blend in NaCl provided a gel of high consistency at ambient temperature (20 - 25 °C), whereas the blend in KCl did not gel in the studied temperature range. The potential stability of the blends was determined by zeta-potential analysis. The low values of ζ-potential indicate that the gelatin/polysaccharide blends are electrically unstable systems which tend to coagulate. The mixtures of gelatin/polysaccharide electrostatic complexes may have a great potential in many food applications. © 2017 Potravinarstvo Slovak Journal of Food Sciences

Ionotropic Gelation of Chitosan Flat Structures and Potential Applications

none6siThe capability of some polymers, such as chitosan, to form low cost gels under mild conditions is of great application interest. Ionotropic gelation of chitosan has been used predominantly for the preparation of gel beads for biomedical application. Only in the last few years has the use of this method been extended to the fabrication of chitosan-based flat structures. Herein, after an initial analysis of the major applications of chitosan flat membranes and films and their usual methods of synthesis, the process of ionotropic gelation of chitosan and some recently proposed novel procedures for the synthesis of flat structures are presented.openSacco P.; Pedroso-Santana S.; Kumar Y.; Joly N.; Martin P.; Bocchetta P.Sacco, P.; Pedroso-Santana, S.; Kumar, Y.; Joly, N.; Martin, P.; Bocchetta, P

Development of a subcortical emphasized physical human head model for evaluation of deep brain source contribution to scalp EEG

Ph.DDOCTOR OF PHILOSOPH

Ultrasensitive Piezoresistive and Piezocapacitive Cellulose-Based Ionic Hydrogels for Wearable Multifunctional Sensing

Tactile sensors, namely, flexible devices that sense physical stimuli, have received much attention in the last few decades due to their applicability in a wide range of fields like the world of wearables, soft robotics, prosthetics, and e-skin. Nevertheless, achieving a trade-off among stretchability, good sensitivity, easy manufacturability, and multisensing ability is still a challenge. Herein, an extremely flexible strain sensor composed of a cellulose-based hydrogel is presented. A natural biocompatible carboxymethylcellulose (CMC) hydrogel endowed with ionic conductivity by sodium chloride (NaCl) was used as the sensitive part. Both the sensible layer and electrodes were investigated with an innovative approach for wearable sensor applications based on electrochemical impedance spectroscopy to find the best device configuration. The sensor, exploitable both as a piezoresistor and as a piezocapacitor, presents high sensitivity to external stimuli, together with an extreme stretchability of up to 600%, showing the best strain and temperature sensitivity among the ionic conductive hydrogel-based devices presented in the literature. The very high strain sensitivity enables the hydrogel to be implemented in wearable strain sensors to monitor different human motions and physiological signals, representing a valid solution for the realization of transparent, easily manufacturable, and low-environmental-impact devices

Ultrasensitive Piezoresistive and Piezocapacitive Cellulose-Based Ionic Hydrogels for Wearable Multifunctional Sensing

Tactile sensors, namely, flexible devices that sense physical stimuli, have received much attention in the last few decades due to their applicability in a wide range of fields like the world of wearables, soft robotics, prosthetics, and e-skin. Nevertheless, achieving a trade-off among stretchability, good sensitivity, easy manufacturability, and multisensing ability is still a challenge. Herein, an extremely flexible strain sensor composed of a cellulose-based hydrogel is presented. A natural biocompatible carboxymethylcellulose (CMC) hydrogel endowed with ionic conductivity by sodium chloride (NaCl) was used as the sensitive part. Both the sensible layer and electrodes were investigated with an innovative approach for wearable sensor applications based on electrochemical impedance spectroscopy to find the best device configuration. The sensor, exploitable both as a piezoresistor and as a piezocapacitor, presents high sensitivity to external stimuli, together with an extreme stretchability of up to 600%, showing the best strain and temperature sensitivity among the ionic conductive hydrogel-based devices presented in the literature. The very high strain sensitivity enables the hydrogel to be implemented in wearable strain sensors to monitor different human motions and physiological signals, representing a valid solution for the realization of transparent, easily manufacturable, and low-environmental-impact devices

Electro-chemo-mechanical deformation studies on polypyrrole covered gelatin fiber scaffolds

http://www.ester.ee/record=b4611227*es