Flexible Piezoresistive Polystyrene Composite Sensors Filled with Hollow 3D Graphitic Shells

The objective of this research was to develop highly effective conductive polymer composite (CPC) materials for flexible piezoresistive sensors, utilizing hollow three-dimensional graphitic shells as a highly conductive particulate component. Polystyrene (PS), a cost-effective and robust polymer widely used in various applications such as household appliances, electronics, automotive parts, packaging, and thermal insulation materials, was chosen as the polymer matrix. The hollow spherical three-dimensional graphitic shells (GS) were synthesized through chemical vapor deposition (CVD) with magnesium oxide (MgO) nanoparticles serving as a support, which was removed post-synthesis and employed as the conductive filler. Commercial multi-walled carbon nanotubes (CNTs) were used as a reference one-dimensional graphene material. The main focus of this study was to investigate the impact of the GS on the piezoresistive response of carbon/polymer composite thin films. The distribution and arrangement of GS and CNTs in the polymer matrix were analyzed using techniques such as X-ray diffraction and scanning electron microscopy, while the electrical, thermal, and mechanical properties of the composites were also evaluated. The results revealed that the PS composite films filled with GS exhibited a more pronounced piezoresistive response as compared to the CNT-based composites, despite their lower mechanical and thermal performance

Facile production of ultra-fine silicon nanoparticles

A facile procedure for the synthesis of ultra-fine silicon nanoparticles without the need for a Schlenk vacuum line is presented. The process consists of the production of a (HSiO1.5)n sol–gel precursor based on the polycondensation of low-cost trichlorosilane (HSiCl3), followed by its annealing and etching. The obtained materials were thoroughly characterized after each preparation step by electron microscopy, Fourier transform and Raman spectroscopy, X-ray dispersion spectroscopy, diffraction methods and photoluminescence spectroscopy. The data confirm the formation of ultra-fine silicon nanoparticles with controllable average diameters between 1 and 5 nm depending on the etching time

Strain regulating and kinetics accelerating of micro-sized silicon anodes via dual-size hollow graphitic carbons conductive additives

Micro-sized silicon (mu Si) anode features fewer interfacial side reactions and lower costs compared to nanosized silicon, and has higher commercial value when applied as a lithium-ion battery (LIB) anode. However, the high localized stress generated during (de)lithiation causes electrode breakdown and performance deterioration of the mu Si anode. In this work, hollow graphitic carbons with tailored dual sizes are employed as conductive additives for the mu Si anode to overcome electrode failure. The dual-size hollow graphitic carbons (HGC) additives consist of particles with micrometer size similar to the mu Si particles; these additives are used for strain regulation. Additionally, nanometer-size particles similar to commercial carbon black Spheron (SP) are used mainly for kinetics acceleration. In addition to building an efficient conductive network, the dual-size hollow graphitic carbon conductive additive prevents the fracture of the electrode by reducing local stress and alleviating volume expansion. The mu Si anode with dual-size hollow graphitic carbons as conductive additives achieves an impressive capacity of 651.4 mAh g(-1) after 500 cycles at a high current density of 2 A g(-1). These findings suggest that dual-size hollow graphitic carbons are expected to be superior conductive additives for micro-sized alloy anodes similar to mu Si.Web of Scienc

Surface modifications for inflow cannulas of ventricular assist devices – comparison of latest solutions

Nowadays, the Mechanical Circulatory Support (MCS) within the Ventricular Assist Devices (VAD) appears to be a reliable and effective solution for patients with advanced heart failure (HF). After many years of work, extracorporeal pulsatile VADs have been replaced by new generations of implantable continuous flow (CF) pumps. Clinical experience has shown that present-day pump constructions still need to be improved to minimize the risk of complications during heart assistance. One of the complications is the pump inflow obstruction caused by the ingrowth of tissue into the blood inflow path and pump thrombosis. The main goal is to develop a coating for the external surface of the inflow cannula to provide controlled tissue ingrowth. The smooth surface of the cannula external wall results in the tissue overgrowth into the pump inflow orifice, and may be a source of emboli. The paper presents external surface modifications of the inflow cannula performed by different VAD manufacturers within the topography characterization. The inflow cannulas used in CF VADs are mainly made of titanium alloy due to its mechanical properties and high biocompatibility. In general, the discussed surface coatings were characterized by the roughness of about ≈ Ra = 15 μm, high porosity and good wettability Φ ≈ 60°. The surface was covered with titanium microspheres or titanium mesh. The developed surfaces and clinical experience confirm the ability to control the tissue ingrowth along the external surfaces of the inflow cannula at the tissue-implant interface

Flexible piezoresistive polystyrene composite sensors filled with hollow 3D graphitic shells

The objective of this research was to develop highly effective conductive polymer composite (CPC) materials for flexible piezoresistive sensors, utilizing hollow three-dimensional graphitic shells as a highly conductive particulate component. Polystyrene (PS), a cost-effective and robust polymer widely used in various applications such as household appliances, electronics, automotive parts, packaging, and thermal insulation materials, was chosen as the polymer matrix. The hollow spherical three-dimensional graphitic shells (GS) were synthesized through chemical vapor deposition (CVD) with magnesium oxide (MgO) nanoparticles serving as a support, which was removed post synthesis and employed as the conductive filler. Commercial multi-walled carbon nanotubes (CNTs) were used as a reference one-dimensional graphene material. The main focus of this study was to investigate the impact of the GS on the piezoresistive response of carbon/polymer composite thin films. The distribution and arrangement of GS and CNTs in the polymer matrix were analyzed using techniques such as X-ray diffraction and scanning electron microscopy, while the electrical, thermal, and mechanical properties of the composites were also evaluated. The results revealed that the PS composite films filled with GS exhibited a more pronounced piezoresistive response as compared to the CNT-based composites, despite their lower mechanical and thermal performance

Recent advances in boron- and nitrogen-doped carbon-based materials and their various applications

Carbon, owing to its unique properties such as surface area, pore features, conductivity, and chemical and thermal stability, has found several applications in the field of sensors, energy storage, electrocatalysis, and hydrogen storage. However, the properties of pristine carbon are sometimes insufficient to meet the requirements of a particular application. Heteroatom co-doping may not only enhance the surface area, improve the porosity, and enhance the redox activity, but it also increases stability. B, N heteroatom co-doping has gained popularity as it is found to be an effective way to enhance the properties of porous carbon by influencing the physicochemical, electrochemical, and electrical properties, thereby widening its applications. In this review, the rational synthetic strategies that are used to produce B, N co-doped carbon are described. Further, the charge conduction in such B, N co-doped carbon-based materials (including metal and metal-free) is discussed in detail. Certain remarkable works representing the various applications of B, N co-doped carbon in the area of electrocatalysis, energy storage (rechargeable batteries and supercapacitors), and sensors are also highlighted. Finally, the review ends with a discussion of the existing challenges and possible future directions of research on B, N co-doped carbon.Web of Science911art. no. 210196

Synergistic protection of Si anode based on multi-dimensional graphitic carbon skeletons

Inspired by the natural corn structure, a Si@hollow graphene shell@graphene (Si@GS@G) anode material was prepared in which silicon nanoparticles were preliminarily anchored onto the surface of an elastic graphene shell and further constrained using graphene sheets. Hollow graphene oxide shells with abundant surficial hydrogen bonds, which were synthesized using a novel bottom-up method, were used as an intermediate material to anchor positively charged silicon nanoparticles via electrostatic attraction and achieve a rational spatial distribution. The inner hollow graphene shell anchorage and outer graphene constraint synergistically constituted a porous and robust conductive corn-like structure. The as-fabricated Si@GS@G anode afforded efficient electron and ion transport pathways and improved structural stability, thereby enhancing Li+ storage capability (505 mAh.g(-1) at 10 A.g(-1)) and extending the lifespan compared to the single hollow graphene shell or graphene sheet-protected Si anode (72% capacity retention after 500 cycles). The improved kinetics of the Si@GS@G anode were investigated using electro impedance spectroscopy, galvanostatic intermittent titration, and pseudocapacitance contribution rate analysis, and the structural evolution was analyzed using ex situ electron microscopy. This study proposes a novel hollow graphene oxide shell as an activated intermediate material for designing a porous electrode structure that facilitates an enhanced electrochemical performance.Web of Scienc

Dynamic <I>in vitro</I> hemocompatibility of oligoproline self-assembled monolayer surfaces

The blood compatibility of self-assembled monolayers (SAMs) of oligoproline, a nonionic antifouling peptide, was investigated using the cone-and-plate assay imitating arterial blood flow conditions. End-capped oligoprolines composed of 6 and 9 proline residues (Pro6 and Pro9) and a Cys residue were synthesized for preparing SAMs (Pro-SAMs) on Au-sputtered glass. The surface of Pro-SAMs indicated hydrophilic property with a smooth topology. The adsorption of blood components and the adhesion of blood cells, including leukocytes and platelets, were strongly suppressed on Pro-SAMs. Moreover, Pro9-SAM did not trigger the activation of platelets (i.e., the conformational change of GPIIb/IIIa and P-selectin (CD62P) expression on platelets and the formation of aggregates). Our results demonstrate that Pro9-SAM completely inhibited acute thrombogenic responses and the activation of platelets under dynamic conditions

Facile production of ultra-fine silicon nanoparticles

A facile procedure for the synthesis of ultra-fine silicon nanoparticles without the need for a Schlenk vacuum line is presented. The process consists of the production of a (HSiO1.5)(n) sol-gel precursor based on the polycondensation of low-cost trichlorosilane (HSiCl3), followed by its annealing and etching. The obtained materials were thoroughly characterized after each preparation step by electron microscopy, Fourier transform and Raman spectroscopy, X-ray dispersion spectroscopy, diffraction methods and photoluminescence spectroscopy. The data confirm the formation of ultra-fine silicon nanoparticles with controllable average diameters between 1 and 5 nm depending on the etching time.Web of Science79art. no. 20073