Understanding the relationship between surfing performance and fin design.

This research aimed to determine whether accomplished surfers could accurately perceive how changes to surfboard fin design affected their surfing performance. Four different surfboard fins, including conventional, single-grooved, and double-grooved fins, were developed using computer-aided design combined with additive manufacturing (3D printing). We systematically installed these 3D-printed fins into instrumented surfboards, which six accomplished surfers rode on waves in the ocean in a random order while blinded to the fin condition.

Edge-Functionalized Graphene/Polydimethylsiloxane Composite Films for Flexible Neural Cuff Electrodes.

The design of neural electrodes has changed in the past decade, driven mainly by the development of new materials that open the possibility of manufacturing electrodes with adaptable mechanical properties and promising electrical properties. In this paper, we report on the mechanical and electrochemical properties of a polydimethylsiloxane (PDMS) composite with edge-functionalized graphene (EFG) and demonstrate its potential for use in neural implants with the fabrication of a novel neural cuff electrode. We have shown that a 200 μm thick 1:1 EFG/PDMS composite film has a stretchability of up to 20%, a Young's modulus of 2.

3D printing of surgical staples.

In this work, CAD design and additive manufacturing (3D printing) are used to fabricate surgical staples. The staples were analysed on their mechanical robustness according to ASTM standard F564-17 which involved the in-house design, prototyping and fabrication (using 3D printing) of specialized grips and extension blocks. Our results indicated that staples 3D printed using carbon fibre reinforced nylon 6 (CF-PA6) exhibited a strength value of 37 ± 3 MPa coupled with an implantation-suitable ductility value of 26 ± 4%.

Gellan Gum Hydrogels Filled Edible Oil Microemulsion for Biomedical Materials: Phase Diagram, Mechanical Behavior, and In Vivo Studies.

The demand for wound care products, especially advanced and active wound care products is huge. In this study, gellan gum (GG) and virgin coconut oil (VCO) were utilized to develop microemulsion-based hydrogel for wound dressing materials. A ternary phase diagram was constructed to obtain an optimized ratio of VCO, water, and surfactant to produce VCO microemulsion.

Performance evaluation of humpback whale-inspired shortboard surfing fins based on ocean wave fieldwork.

We present field results revealing improved surfing performance when a novel approach ("Real Whale", RW) is used for applying several of the humpback whale's passive flow control mechanisms, including tubercles, to surfboard fins. It is also the first study presenting evidence of dynamic performance of tubercled designs rotating on all three axes. We evaluated low aspect ratio, thruster-style 3-fin configurations used in high-performance surfing.

Bioinspired 3D Printable Soft Vacuum Actuators for Locomotion Robots, Grippers and Artificial Muscles.

Continued technological progress in robotic systems has led to more applications where robots and humans operate in close proximity and even physical contact in some cases. Soft robots, which are made of highly compliant and deformable materials, provide inherent safety features unlike conventional robots that are made of stiff and rigid components. Soft robotics is a rapidly developing field exploiting biomimetic design principles, novel sensor and actuation concepts, and advanced manufacturing techniques.

Degradable 3D-Printed Hydrogels Based on Star-Shaped Copolypeptides.

We present a star copolypeptide-based hydrogel ink capable of structural microfabrication using 3D extrusion printing. The material comprises an amphiphilic block copolymer structure of poly(benzyl-l-glutamate)- b-oligo(l-valine), which spontaneously forms hydrogels through hydrophobic interactions. The chemical design allows the bulk phase of the hydrogel to remain intact after application of shear due to its self-recovery behavior.

Conducting hydrogels for edible electrodes.

The development of highly swollen, strong, conductive hydrogel materials is necessary for the advancement of edible device research. Using a gellan gum/gelatin ionic-covalent entanglement (ICE) hydrogel, a simple method of producing conductive, edible hydrogels is described. ICE gels containing NaCl or CsCl were developed which exhibited conductivities of 200 ± 20 mS cm and 380 ± 30 mS cm, respectively.

Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides.

Reaction products from the ozonolysis of unsaturated lipids at gas-liquid interfaces have the potential to significantly influence the chemical and physical properties of organic aerosols in the atmosphere. In this study, the gas-phase dissociation behavior of lipid secondary ozonides is investigated using ion-trap mass spectrometry. Secondary ozonides were formed by reaction between a thin film of unsaturated lipids (fatty acid methyl esters or phospholipids) with ozone before being transferred to the gas phase as [M + Na] ions by electrospray ionization.

3D Printing of Transparent and Conductive Heterogeneous Hydrogel-Elastomer Systems.

A hydrogel-dielectric-elastomer system, polyacrylamide and poly(dimethylsiloxane) (PDMS), is adapted for extrusion printing for integrated device fabrication. A lithium-chloride-containing hydrogel printing ink is developed and printed onto treated PDMS with no visible signs of delamination and geometrically scaling resistance under moderate uniaxial tension and fatigue. A variety of designs are demonstrated, including a resistive strain gauge and an ionic cable.

Self-Healing Hydrogels.

Over the past few years, there has been a great deal of interest in the development of hydrogel materials with tunable structural, mechanical, and rheological properties, which exhibit rapid and autonomous self-healing and self-recovery for utilization in a broad range of applications, from soft robotics to tissue engineering. However, self-healing hydrogels generally either possess mechanically robust or rapid self-healing properties but not both. Hence, the development of a mechanically robust hydrogel material with autonomous self-healing on the time scale of seconds is yet to be fully realized.

Effect of heterocyclic capping groups on the self-assembly of a dipeptide hydrogel.

The mechanism and design rules associated with the self-assembly of short peptides into hydrogels is currently not well understood. In this work, four diphenylalanine-based peptides have been synthesised, bearing heterocyclic capping groups which have different degrees of hydrogen bonding potential and nitrogen substitution. For these four peptides, zeta potential and electrical impedance spectroscopy measurements were undertaken to monitor gelation, with the impedance data showing different gelation times for each peptide hydrogel.

Development of carboxymethyl cellulose-based hydrogel and nanosilver composite as antimicrobial agents for UTI pathogens.

Silver nanoparticles (AgNPs) containing hydrogel composite were first synthesized by preparing a new hydrogel from carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and the cross-linker ethylene glycol diglycidyl ether (EGDE), followed by the incorporation of AgNPs by microwave radiation. The resulting neat hydrogels and AgNPs-hydrogel composites were characterized using spectral, thermal, microscopic analysis and X-ray diffraction (XRD) analyses. The SEM and TEM results demonstrated that the synthesized AgNPs were spherical with diameters ranging from 8 to 14nm.

3D printing of layered brain-like structures using peptide modified gellan gum substrates.

The brain is an enormously complex organ structured into various regions of layered tissue. Researchers have attempted to study the brain by modeling the architecture using two dimensional (2D) in vitro cell culturing methods. While those platforms attempt to mimic the in vivo environment, they do not truly resemble the three dimensional (3D) microstructure of neuronal tissues.

4D Printing with Mechanically Robust, Thermally Actuating Hydrogels.

A smart valve is created by 4D printing of hydrogels that are both mechanically robust and thermally actuating. The printed hydrogels are made up of an interpenetrating network of alginate and poly(N-isopropylacrylamide). 4D structures are created by printing the "dynamic" hydrogel ink alongside other static materials.

Filling of carbon nanotubes and nanofibres.

The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications.

Poly(3,4-ethylenedioxythiophene):dextran sulfate (PEDOT:DS) - a highly processable conductive organic biopolymer.

A novel water-dispersible conducting polymer analogous to poly(3,4-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been chemically synthesized in a single reaction in high yield. PEDOT:DS, a new member of the polythiophene family, is composed of a complex between PEDOT and the sulfonated polysaccharide polyanion dextran sulfate. Drop-cast films of aqueous suspensions of the material display a native conductivity of up to 7 ± 1 S cm(-1), increasing to 20 ± 2 S cm(-1) after treatment with ethylene glycol and thermal annealing.

Three-dimensional printing fiber reinforced hydrogel composites.

An additive manufacturing process that combines digital modeling and 3D printing was used to prepare fiber reinforced hydrogels in a single-step process. The composite materials were fabricated by selectively pattering a combination of alginate/acrylamide gel precursor solution and an epoxy based UV-curable adhesive (Emax 904 Gel-SC) with an extrusion printer. UV irradiation was used to cure the two inks into a single composite material.

Robust biopolymer based ionic-covalent entanglement hydrogels with reversible mechanical behaviour.

Emerging applications of hydrogels such as soft robotics and cartilage tissue scaffolds require hydrogels with enhanced mechanical performance. We report the development of a robust biopolymer based ionic-covalent entanglement network hydrogel made from calcium cross-linked gellan gum and genipin cross-linked gelatin. The ratio of the two polymers and the cross-linker concentrations significantly affected the mechanical characteristics of the hydrogels.

Enhanced gelation properties of purified gellan gum.

Gellan gum is a hydrogel-forming polysaccharide when combined with monovalent or divalent cations such as sodium, magnesium, potassium or calcium. Commercially, gellan gums are sold with trace amounts of these cations, which have been proven to affect the gelation and mechanical properties of the resultant hydrogels. A new method based on impedance analysis for determining the gel transition temperature of purified and un-purified gellan gum is presented.

Extrusion printing of ionic-covalent entanglement hydrogels with high toughness.

Three-dimensional (3D) printing of hydrogels has recently been investigated for use in tissue engineering applications. One major limitation in the use of synthetic hydrogels is their poor mechanical robustness but the development of 'tough hydrogels' in conjunction with additive fabrication techniques will accelerate the advancement of many technologies including soft robotics, bionic implants, sensors and controlled release systems. This article demonstrates that ionic-covalent entanglement (ICE) gels can be fabricated through a modified extrusion printing process that facilitates in situ photopolymerisation.

Surface analysis of lipids by mass spectrometry: more than just imaging.

Mass spectrometry is now an indispensable tool for lipid analysis and is arguably the driving force in the renaissance of lipid research. In its various forms, mass spectrometry is uniquely capable of resolving the extensive compositional and structural diversity of lipids in biological systems. Furthermore, it provides the ability to accurately quantify molecular-level changes in lipid populations associated with changes in metabolism and environment; bringing lipid science to the "omics" age.

Biofabrication: an overview of the approaches used for printing of living cells.

The development of cell printing is vital for establishing biofabrication approaches as clinically relevant tools. Achieving this requires bio-inks which must not only be easily printable, but also allow controllable and reproducible printing of cells. This review outlines the general principles and current progress and compares the advantages and challenges for the most widely used biofabrication techniques for printing cells: extrusion, laser, microvalve, inkjet and tissue fragment printing.