Fabrication, Characterization, and Properties of Poly (Ethylene-Co-Vinyl Acetate) Composite Thin Films Doped with Piezoelectric Nanofillers

Vertical Etching of Scandium Aluminum Nitride Thin Films Using TMAH Solution

A wide bandgap, an enhanced piezoelectric coefficient, and low dielectric permittivity are some of the outstanding properties that have made ScxAl1-xN a promising material in numerous MEMS and optoelectronics applications. One of the substantial challenges of fabricating ScxAl1-xN devices is its difficulty in etching, specifically with higher scandium concentration. In this work, we have developed an experimental approach with high temperature annealing followed by a wet etching process using tetramethyl ammonium hydroxide (TMAH), which maintains etching uniformity across various Sc compositions. The experimental results of etching approximately 730 nm of ScxAl1-xN (x = 0.125, 0.20, 0.40) thin films show that the etch rate decreases with increasing scandium content. Nevertheless, sidewall verticality of 85°~90° (±0.2°) was maintained for all Sc compositions. Based on these experimental outcomes, it is anticipated that this etching procedure will be advantageous in the fabrication of acoustic, photonic, and piezoelectric devices.

Deposition, Characterization, and Modeling of Scandium-Doped Aluminum Nitride Thin Film for Piezoelectric Devices

In this work, we systematically studied the deposition, characterization, and crystal structure modeling of ScAlN thin film. Measurements of the piezoelectric device's relevant material properties, such as crystal structure, crystallographic orientation, and piezoelectric response, were performed to characterize the Sc0.29Al0.71N thin film grown using pulsed DC magnetron sputtering. Crystal structure modeling of the ScAlN thin film is proposed and validated, and the structure-property relations are discussed. The investigation results indicated that the sputtered thin film using seed layer technique had a good crystalline quality and a clear grain boundary. In addition, the effective piezoelectric coefficient d33 was up to 12.6 pC/N, and there was no wurtzite-to-rocksalt phase transition under high pressure. These good features demonstrated that the sputtered ScAlN is promising for application in high-coupling piezoelectric devices with high-pressure stability.

Mortise-tenon joint structured hydrophobic surface-functionalized barium titanate/polyvinylidene fluoride nanocomposites for printed self-powered wearable sensors

Self-powered wearable sensors exhibiting high sensitivity and flexibility have attracted widespread interest in the field of wearable electronics. Herein, a 3D printing technique was employed to fabricate a fully printed, flexible self-powered sensor with high piezoelectric performance. This printing technique is based on the hydrophobic surface-functionalized barium titanate (FD-BTO)/polyvinylidene fluoride (PVDF) composite film. To strengthen the interface bond between BTO and PVDF, the BTO nanoparticles were surface functionalized using hydrophobic 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES). As a result, there was an increase in the content of the β-phase in the PFDTES modified BTO (FD-BTO) nanoparticle composite film. The 3D-printed self-powered sensor based on the optimum FD-BTO/PVDF composite film exhibited excellent sensitivity (61.6 mV kPa-1) with a piezoelectric coefficient (d33) of 69.1 pC/N, which is two-fold higher than that of the unfunctionalized BTO/PVDF counterpart. Additionally, the power sensor displayed excellent mechanical durability in the 20 000 cyclic force tests. In practice, the printed devices were used as a sports wearable device to monitor and analyze athlete motion, and a self-powered printed sensor array (5 × 5), which could effectively detect the pattern image of the external pressure input. The 3D-printed self-powered sensor demonstrated herein can contribute significantly to the applications and the development of printed electronic wearable devices.

Controlled local release of PPARγ agonists from biomaterials to treat peripheral nerve injury

OBJECTIVE

Poor clinical outcomes following peripheral nerve injury (PNI) are partly attributable to the limited rate of neuronal regeneration. Despite numerous potential drug candidates demonstrating positive effects on nerve regeneration rate in preclinical models, no drugs are routinely used to improve restoration of function in clinical practice. A key challenge associated with clinical adoption of drug treatments in nerve injured patients is the requirement for sustained administration of doses associated with undesirable systemic sideeffects. Local controlled-release drug delivery systems could potentially address this challenge, particularly through the use of biomaterials that can be implanted at the repair site during the microsurgical repair procedure.

APPROACH

In order to test this concept, this study used various biomaterials to deliver ibuprofen sodium or sulindac sulfide locally in a controlled manner in a rat sciatic nerve injury model. Following characterisation of release parameters in vitro, ethylene vinyl acetate tubes or polylactic-co-glycolic acid wraps, loaded with ibuprofen sodium or sulindac sulfide, were placed around directly-repaired nerve transection or nerve crush injuries in rats.

MAIN RESULTS

Ibuprofen sodium, but not sulindac sulfide caused an increase in neurites in distal nerve segments and improvements in functional recovery in comparison to controls with no drug treatment.

SIGNIFICANCE

This study showed for the first time that local delivery of ibuprofen sodium using biomaterials improves neurite growth and functional recovery following PNI and provides the basis for future development of drug-loaded biomaterials suitable for clinical translation.

Biochar as an Effective Filler of Carbon Fiber Reinforced Bio-Epoxy Composites

The goal of this work was to investigate the effect of the biochar additive (2.5; 5; 10 wt.%) on the properties of carbon fiber-reinforced bio-epoxy composites. The morphology of the composites was monitored by scanning electron microscopy (SEM), and the thermomechanical properties by dynamic mechanical thermal analysis (DMTA). Additionally, mechanical properties such as impact strength, flexural strength andtensile strength, as well as the thermal stability and degradation kinetics of these composites were evaluated. It was found that the introduction of biochar into the epoxy matrix improved the mechanical and thermal properties of carbon fiber-reinforced composites.

Influence of Polymer Composition on the Controlled Release of Docetaxel: A Comparison of Non-Degradable Polymer Films for Oesophageal Drug-Eluting Stents

Following the huge clinical success of drug-eluting vascular stents, there is a significant interest in the development of drug-eluting stents for other applications, such as the treatment of gastrointestinal (GI) cancers. Central to this process is understanding how particular drugs are released from stent coatings, which to a large extent is controlled by drug-polymer interactions. Therefore, in this study we investigated the release of docetaxel (DTX) from a selection of non-degradable polymer films. DTX-polymer films were prepared at various loadings (1, 5 and 10% w/w) using three commercially available polymers including poly(dimethylsiloxane) (PSi), poly (ethylene-co-vinyl acetate) (PEVA) and Chronosil polyurethane (PU). The formulations were characterised using different techniques such as photoacoustic Fourier-transform infrared (PA-FTIR) spectrophotometry, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The effect of DTX on the mechanical properties of the films, in-vitro release, and degradation tests were also assessed. For all polymers and DTX loadings, the drug was found to disperse homogenously without crystallisation within the polymer matrix. While no specific interactions were observed between DTX and PSi or PEVA, hydrogen-bonding appeared to be present between DTX and PU, which resulted in a concentration-dependent decrease in the Young’s moduli of the films due to disruption of inter-polymeric molecular interactions. In addition, the DTX-PU interactions were found to modulate drug release, providing near-linear release over 30 days, which was accompanied by a significant reduction in degradation products. The results indicate that DTX-loaded PU films are excellent candidates for drug-eluting stents for the treatment of oesophageal cancer.

Synthesis and Modification of Nanostructured Thin Films

The idea of nanomaterials, nanoscience, and nanotechnologies was formulated by Richard Feynman in 1959 in his famous lecture "There's Plenty of Room at the Bottom" [...].