‘Anti-aging’ chemistry taken from nature overcomes next-gen lithium battery decay

Phys.org  November 15, 2021 Degradation occurs pretty much everywhere in nature since oxygen is one of the elements most capable of attracting electrons from other atoms and molecules. Organisms often produce different types of enzymes that work to scavenge active oxygen and free radicals to alleviate the issue. Inspired by the anti-oxygen coping mechanisms in nature researchers in China developed a photostabilizer—a simple, anti-aging binder additive to the electrolyte that can scavenge the singlet oxygen atoms and free radicals as they occur. Through experimental investigation and theoretical calculation, they found that the scavenging mechanism in layered transition metal oxides-based lithium […]

Flexible, stretchable battery capable of moving smoothly like snake scales

Nanowerk  September 28, 2021 Researchers in South Korea have made a structure with individual, overlapping units, similar to snake scales that can be used to construct shape-morphing batteries for untethered soft robots. They created it by folding well-defined, two-dimensional patterns with cutouts, the folding lines mimicking the hinge structure of snakeskin, enabling stable deformations without mechanical damage to rigid cells. The structure is applied to a stretchable Li-ion battery, constructed to form an arrangement of electrically interconnected, hexagonal pouch cells. Simulation confirmed that the battery maintains its performance under dynamic deformation with a 90% stretching ratio and 10-mm-radius bending curve, […]

Unbreakable glass inspired by seashells

Phys.org  September 28, 2021 Nacre, mother of pearl, made of stiff pieces of chalk-like matter that are layered with highly elastic soft proteins, has the rigidity of a stiff material and durability of a soft material. It is 3000 times tougher than the materials that compose it. An international team of researchers (Canada, USA- University of Colorado) took the architecture of nacre and replicated it with layers of glass flakes and acrylic, yielding an exceptionally strong yet opaque material that can be produced easily and inexpensively. They made the composite optically transparent. By tuning the refractive index of the acrylic, […]

Winged microchip is smallest-ever human-made flying structure

Science Daily  September 22, 2021 An international team of researchers (South Korea, UK, USA – Northwestern University, University of Wisconsin, University of Connecticut, University of Illinois, University of Purdue, China, Hong Kong) studied wind-dispersed seeds to build microfliers and optimized its aerodynamics to ensure that it falls at a slow velocity in a controlled manner. They fabricated precursors to flying structures in flat, planar geometries and bonded them onto a slightly stretched rubber substrate. When the stretched substrate is relaxed, a controlled buckling process occurred causing the wings to “pop up” into precisely defined three-dimensional forms. It included sensors, a […]

Engineering a polymer network to act as active camouflage on demand

Phys.org  September 16, 2021 Despite extensive efforts to create colour-changing materials and devices, it is challenging to achieve pixelated structural coloration with broadband spectral shifts in a compact space. An international team of researchers (USA – University of Pennsylvania, South Korea) describes pneumatically inflating thin membranes of main-chain chiral nematic liquid crystalline elastomers that have such properties. By taking advantage of the large elasticity anisotropy and Poisson’s ratio (>0.5) of these materials, they geometrically programed the size and the layout of the encapsulated air channels to achieve colour shifting from near-infrared to ultraviolet wavelengths with less than 20% equi-biaxial transverse […]

World’s first discovery of liquid directional steering on a bio-inspired surface

Phys.org  September 16, 2021 A liquid deposited on a surface tends to move along directions that reduce surface energy, which is mainly dictated by surface properties rather than liquid properties, such as surface tension. Achieving well-controlled directional steering remains challenging because the liquid-solid interaction mainly occurs in the 2D domain. An international team of researchers (China, Hong Kong) has shown that the spreading direction of liquids with different surface tensions can be tailored by designing 3D capillary ratchets that create an asymmetric and 3D spreading profile both in and out of the surface plane. Such directional steering is also accompanied […]

Water-repellent nanomaterial inspired by nature

Science Daily  September 7, 2021 Using colloidal gels of fullerite C60 and C70 nanocrystals researchers at the University of Central Florida have developed superhydrophobic films and coatings. They demonstrated that despite the high surface energy of these van der Waals molecular crystals their gelation can create films having self-affine fractal surfaces with multiscale roughness. In experiments when submerged in water the material stayed dry up to 3 h even at a water depth of two feet and exhibit the plastron effect. According to the researchers non-wettable films of such materials are unique as fullerites get photosensitized instantaneously generating extremely high […]

Lightweight composite material inspects itself: Changes in color indicate deformations

Science Daily  August 23, 2021 An international team of researchers (Switzerland, UK) developed a new type of laminate that changes color as soon as the material is deformed. The laminate is composed of alternating layers of a plastic polymer and artificial nacre or mother-of-pearl and is modelled on the biological example of the mussel shell. It consists of glass platelets arranged in parallel, which are compacted, sintered, and solidified using a polymeric resin making it extremely hard and break-resistant. The second layer consists of a polymer and an indicator molecule synthesised specifically for this application. The molecule is activated as […]

Microbially produced fibers: Stronger than steel, tougher than Kevlar

Phys.org  July 21, 2021 A problem associated with recombinant spider silk fiber is the need to create β-nanocrystals, a main component of natural spider silk, which contributes to its strength. Researchers at Washington University redesigned the silk sequence by introducing amyloid sequences that have high tendency to form β-nanocrystals. They created different polymeric amyloid proteins using three well-studied amyloid sequences as representatives. The resulting proteins had less repetitive amino acid sequences than spider silk, making them easier to be produced by engineered bacteria. The longer the protein, the stronger and tougher the resulting fiber. The 128-repeat proteins resulted in a […]

Electrohydraulic arachno-bot a fascinating lightweight

EurekAlert  June 16, 2021 Researchers at the University of Colorado exploited the principles of spiders’ joints to drive articulated robots without any bulky components and connectors. The Electrohydraulic Soft-actuated joints (SES) joints comprised of both rigid and softer elements can be used in many different configurations. The joints use electrostatic forces to locally pressurize a hydraulic fluid, and cause flexion of a segmented structure. SES joints with rotation angles up to 70° blocked torques up to 70 mN m, and specific torques up to 21 N m kg−1 have been demonstrated. SES joints demonstrated high speed operation, with measured roll-off […]