Examinando por Autor "Bosque, Antonio del"

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A proof of concept of a structural supercapacitor made of graphene coated woven carbon fibers: EIS study and mechanical performance
(Elsevier, 2021) Sánchez-Romate, Xoan F.; Bosque, Antonio del; Artigas-Arnaudas, Joaquín; Muñoz, Bianca K.; Sánchez, María; Ureña, Alejandro
A multifunctional supercapacitor based on a graphene nanoplatelet (GNP) coated woven carbon fiber (WCF) composite has been manufactured and its electrochemical and mechanical performance has been evaluated. Specific capacitance from voltammetry tests is about three times higher than the non-coated WCFs and several orders of magnitude above neat polymer WCF composites. Furthermore, an electrochemical impedance spectroscopy (EIS) analysis has been carried out in the coated and non-coated WCF capacitors. The equivalent circuit consisted on a series/parallel resistance/constant phase elements. EIS results show that the coated samples have superior capacitor properties, confirmed by chronoamperometry tests. The values of energy and peak power densities were also significantly higher in the coated WCFs, proving higher capabilities as supercapacitors. In addition, mechanical performance of structural supercapacitor is affected by the simultaneous addition of a polymer electrolyte and GNPs, with a reduction of mechanical strength when compared to neat polymer composites. However, and due to the lower viscosity of the electrolyte, there is a higher compaction of the material promoting an increase of WCF volume fraction on the LY-PEGDGE matrix samples, leading to similar values of Young Modulus. Despite the detriment of mechanical properties, they were far above other WCF-based structural supercapacitors. The proof of concept by illuminating a LED was highly successful, proving promising capabilities as structural supercapacitors.
Highly Flexible Strain Sensors Based on CNT-Reinforced Ecoflex Silicone Rubber for Wireless Facemask Breathing Monitoring via Bluetooth
(ACS, 2023) Bosque, Antonio del; Fernández Sánchez-Romate, Xoan Xosé; Llana Calvo, Álvaro de la; Fernández, Pedro Rafael; Borromeo, Susana; Sánchez, María; Ureña, Alejandro
Highly stretchable strain sensors based on carbon nanotube (CNT)-reinforced Ecoflex silicone rubber are developed for breathing monitoring purposes. The addition of CNTs promotes an improvement in electrical conductivity and mechanical properties (Young’s modulus and tensile strength) due to its good dispersion in Ecoflex. The evaluation of strain monitoring response, in both tensile and compression conditions, indicates a wide strain detection range and an ultrasensitive response at high strain levels, reaching a gauge factor of around 104 at 70% or 105 at 300% for 0.3 and 0.7 wt % CNT-reinforced sensors, respectively. They show a quite stable electrical response under 2000 cycling loads and different levels of frequencies. Moreover, the response and recovery times are in the range of milliseconds (∼600 and ∼800 ms, respectively). Finally, a proof-of-concept of wireless facemask breathing monitoring was carried out with Bluetooth Low Energy technology and a platform that has been developed to acquire, filter, visualize, and store the breathing signal. With this, the respiration rate can be unequivocally monitored as well as the difference between inspiration and expiration. Thus, this type of trial is proposed for breath monitoring in medical analysis, emergency teams, or first aid.
Highly stretchable strain sensors based on graphene nanoplatelet-doped ecoflex for biomedical purposes
(Elsevier, 2023) Bosque, Antonio del; Sánchez-Romate, Xoan F.; Gómez, Alberto; Sánchez, María; Ureña, Alejandro
Ultrasensitive and highly stretchable strain sensors based on graphene nanoplatelet (GNP) doped Ecoflex are proposed. First, the electrical and electromechanical properties are deeply studied. It has been observed that the electrical conductivity significantly increases with GNP content, indicating that the saturation of the electrical network is not reached, even for the samples with 10 wt. % GNP, confirmed by SEM analysis. Furthermore, the analysis of the electromechanical behavior reveals a very high electrical sensitivity, with a gauge factor (GF) of around 25 at ε = 1 % and 3⋅104 at ε = 30 % in tensile and around 12 at ε = 1 % and 104 at ε = 30 % in compression. Furthermore, the electrical response was found to be stable under medium and long-term cycling tests, proving the high robustness of the proposed sensors. Finally, several proof-of-concept tests are carried out with the optimized sensor, proving the high applicability of the proposed material as pressure sensors, for breathing and wrist pulse monitoring, where the electromechanical responses in a relaxed or tired state are clearly distinguishable, proving the high potential of the developed sensors for biomedical purposes.
Mechanical and Sensing Performance under Hydrothermal Ageing of Wearable Sensors Made of Polydimethylsiloxane with Graphitic Nanofillers
(Elsevier, 2023) Bosque, Antonio del; Sánchez-Romate, Xoan F.; Calvo, Diego; Sánchez, María; Ureña, Alejandro
The effect of hydrothermal ageing on flexible wearable sensors made of PDMS reinforced with graphitic nanofillers (carbon nanotubes, CNTs, and graphene nanoplatelets, GNPs) is explored. It is observed that the nanofiller addition, especially in case of GNPs, promotes a much higher water uptake at saturation due to the higher water diffusion as the generalized porosity is much more significant. However, it does not harm the mechanical properties in comparison with unaged samples, as these water molecules are not prevalently incorporated into the polymer network (around 0.3% water uptake in neat resin). Furthermore, the electrical properties at unstrained state are not severely affected but the electromechanical ones, which are much more sensitive to any change in the electrical network, drastically change with hydrothermal ageing. The gauge factor significantly increases in the case of GNP-doped samples, due to the higher separation between neighbouring nanofillers induced by the slight polymer swelling. The ultra-sensitivity of GNP-doped sensors (up to 100 at very low strains and above 106 at high strain levels) makes them very applicable for the detection of small human movements. For this purpose, a trial with a 2-month-aged GNP-doped sensor was successfully carried out in terms of neck and wrist pulse monitoring.
Thermomechanically Robust Ceramic/Polymer Nanocomposites Modified with Ionic Liquid for Hybrid Polymer Electrolyte Applications
(ACS, 2022) Bosque, Antonio del; Muñoz, Bianca K.; Sánchez, María; Ureña, Alejandro
The development of hybrid electrolytes (HEs) that allows high mechanical properties and high ionic conductivity is a key in the smart mobility progress. In this article, various solid polymer electrolytes (SPEs) based on a blend of epoxy resins, ionic liquid, and titania or alumina nanoparticles have been manufactured and their electrochemical and thermomechanical performances have been evaluated. The combination of SPE components providing the highest properties was studied, having a significant influence on the type of nanoparticles and their dispersion. The electrolyte with the best combination of properties was L65P35(ILE)Al2, which showed Tg = 83 °C and E′ at 30 °C = 1.2 GPa as thermomechanical properties, and σ0 = 7 × 10–4 S/cm, σ1 = 1.6 × 10–6 S/cm, and Csp = 5.6 × 10–5 F/g at room temperature, as electrochemical properties. Moreover, the optimized electrolyte followed the Arrhenius ion transport model (Ea = 24.7 kJ/mol). These results would be promising for use as hybrid electrolyte in structural applications.
Ultrasensitive and highly stretchable sensors for human motion monitoring made of graphene reinforced polydimethylsiloxane: Electromechanical and complex impedance sensing performance
(Elsevier, 2022) Bosque, Antonio del; Sánchez-Romate, Xoan F.; Sánchez, María; Ureña, Alejandro
Highly stretchable sensors based on graphene nanoplatelet (GNP) reinforced polydimethylsiloxane (PDMS) are manufactured for human motion monitoring purposes. The strain sensing analysis shows ultra-high gauge factor (GF) values from 40 to 300 at low strain levels up to 106 at high deformations at tensile conditions, and a decreasing sensitivity as GNP content increases. The compressive behavior shows an initial decrease of the electrical resistance, due to the prevalence of in-plane mechanisms, followed by a stable increase, due to the prevalence of out-of-plane mechanisms. In this regard, the Electrical Impedance Spectroscopy (EIS) analysis shows an increase of the complex impedance with increasing compressive strain. The equivalent RC-LRC circuit allows to explain the electrical mechanisms governing the compressive behavior, where the LRC element denotes the contact and intrinsic resistance and the RC element the tunnelling effect. Finally, a proof of concept of human motion monitoring proves the capability of the scalable and easy-manufactured sensors to detect frowning, raising eyebrows, blinking, breathing, blowing and, even, vocal cord motion, where each phoneme follows a unique pattern, with a robust electrical response.
Ultrasensitive Flexible Strain Sensors Based on Graphene Nanoplatelets doped Poly(Ethylene Glycol) Diglycidyl Ether: Mask Breathing Monitoring for the Internet of Things
(Elsevier, 2023) Bosque, Antonio del; Sánchez–Romate, Xoan F.; Patrizi, David; Sánchez del Río Sáez, José; Wang, De-Yi; Sánchez, María; Ureña, Alejandro
Ultrasensitive and stretchable strain sensors based on graphene nanoplatelet (GNP) doped poly(ethylene glycol) diglycidyl ether (PEGDGE) for human motion monitoring purposes with remote tracking by using Internet of Things (IoT) technologies are synthesized. The quasi–static and cycling responses under both tensile and compression conditions of nanocomposites are studied in detail. On one hand, quasi-static analysis shows very high values of the gauge factor, reaching values around 50–100 at low strain levels (1–2%) and 1000–2500 at high strain levels (10%) in tensile mode, with increasing sensitivity with decreasing GNP content. In addition, electromechanical response under 500 tensile and compression load cycles up to 1%, 2.5%, and 5% strain levels proves their high stability and as a result, their high sensitivity to detect a low degree of strain levels. Three general proofs–of–concept demonstrate that these sensors can detect several types of deformations such as pressure, bending, and twisting. Finally, human breathing is monitored with the sensor attached to a conventional mask. Different breath rhythms combining the calm and excited states of a person walking are remotely sent and monitored on the internet by using different IoT platforms.