3 research outputs found
Highly Sensitive and Very Stretchable Strain Sensor Based on a Rubbery Semiconductor
There is a growing interest in developing
stretchable strain sensors to quantify the large mechanical deformation
and strain associated with the activities for a wide range of species,
such as humans, machines, and robots. Here, we report a novel stretchable
strain sensor entirely in a rubber format by using a solution-processed
rubbery semiconductor as the sensing material to achieve high sensitivity,
large mechanical strain tolerance, and hysteresis-less and highly
linear responses. Specifically, the rubbery semiconductor exploits π–π
stacked polyÂ(3-hexylthiophene-2,5-diyl) nanofibrils (P3HT-NFs) percolated
in silicone elastomer of polyÂ(dimethylsiloxane) to yield semiconducting
nanocomposite with a large mechanical stretchability, although P3HT
is a well-known nonstretchable semiconductor. The fabricated strain
sensors exhibit reliable and reversible sensing capability, high gauge
factor (gauge factor = 32), high linearity (<i>R</i><sup>2</sup> > 0.996), and low hysteresis (degree of hysteresis <12%)
responses at the mechanical strain of up to 100%. A strain sensor
in this format can be scalably manufactured and implemented as wearable
smart gloves. Systematic investigations in the materials design and
synthesis, sensor fabrication and characterization, and mechanical
analysis reveal the key fundamental and application aspects of the
highly sensitive and very stretchable strain sensors entirely from
rubbers
Self-Healing Phenomenon and Dynamic Hardness of C<sub>60</sub>-Based Nanocomposite Coatings
The
phenomenon of surface self-healing in C<sub>60</sub>-based
polymer coatings deposited by ion-beam assisted physical vapor deposition
was investigated. Nanoindentation of the coatings led to the formation
of a protrusion rather than an indent. This protrusion was accompanied
by an abnormal shape of the force–distance curve, where the
unloading curve lies above the loading curve due to an additional
force applied in pulling the indenter out of the media. The coatings
exhibited a nanocomposite structure that was strongly affected by
the ratio of C<sub>60</sub> ion and C<sub>60</sub> molecular beam
intensities during deposition. The coatings also demonstrated the
dynamic hardness effect, where the effective value of the hardness
depends significantly on the indentation speed
Nanohole-Structured and Palladium-Embedded 3D Porous Graphene for Ultrahigh Hydrogen Storage and CO Oxidation Multifunctionalities
Atomic-scale defects on carbon nanostructures have been considered as detrimental factors and critical problems to be eliminated in order to fully utilize their intrinsic material properties such as ultrahigh mechanical stiffness and electrical conductivity. However, defects that can be intentionally controlled through chemical and physical treatments are reasonably expected to bring benefits in various practical engineering applications such as desalination thin membranes, photochemical catalysts, and energy storage materials. Herein, we report a defect-engineered self-assembly procedure to produce a three-dimensionally nanohole-structured and palladium-embedded porous graphene hetero-nanostructure having ultrahigh hydrogen storage and CO oxidation multifunctionalities. Under multistep microwave reactions, agglomerated palladium nanoparticles having diameters of ∼10 nm produce physical nanoholes in the basal-plane structure of graphene sheets, while much smaller palladium nanoparticles are readily impregnated inside graphene layers and bonded on graphene surfaces. The present results show that the defect-engineered hetero-nanostructure has a ∼5.4 wt % hydrogen storage capacity under 7.5 MPa and CO oxidation catalytic activity at 190 °C. The defect-laden graphene can be highly functionalized for multipurpose applications such as molecule absorption, electrochemical energy storage, and catalytic activity, resulting in a pathway to nanoengineering based on underlying atomic scale and physical defects