A smart sensor that can be woven into everyday life

A hybrid design combines sensitivity and flexibility to create an acoustic single-fibre sensor that can be knitted into fabric. The future of tracking our health and fitness looks wearable — and perhaps even implantable

Performance study of a novel solar solid dehumidification/regeneration bed for use in buildings air conditioning systems

In this paper, a novel solar solid dehumidification/regeneration bed has been proposed, and its three regeneration methods, i.e., simulated solar radiation regeneration, microwave regeneration, and combined regeneration of the microwave and simulated solar radiation, were experimentally investigated and compared, as well as the dehumidification performance. The degree of regeneration of the proposed system under the regeneration method combining both microwave irradiation and simulated solar radiation could reach 77.7%, which was 3.77 times higher than that of the system under the simulated solar regeneration method and 1.05 times higher than that of the system under the microwave regeneration. The maximum energy efficiency of the proposed system under the combined regeneration method was 21.7%, while it was only 19.4% for the system under microwave regeneration. All these proved that the combined regeneration method of the simulated solar and microwave radiation not only improved the regeneration efficiency of the system, but also enhanced the energy efficiency. For the dehumidification performance, the maximum transient moisture removal was 14.1 g/kg, the maximum dehumidification efficiency was 68.0% and the maximum speed of dehumidification was 0.294 g/(kgμs) when the inlet air temperature was at 26.09 °C and the air relative humidity was at 89.23%. By comparing the testing results with the semi-empirical results from the Page model, it was indicated that the Page model can predict the regeneration characteristics of the novel solar solid dehumidification/regeneration bed under the combined method of microwave and simulated solar regeneration. The results of this research should prove useful to researchers and engineers to exploit the potential of solar technologies in buildings worldwide

Electrospun 1D and 2D Carbon and Polyvinylidene Fluoride (PVDF) Piezoelectric Nanocomposites

Piezoelectric nanocomposite fibrous membranes consisting of polymer polyvinylidene fluoride (PVDF) as matrix and incorporating 1D carbon nanotubes (CNTs) and 2D graphene oxide (GO) were prepared using an electrospinning process. The influence of the filler type, loading, and dispersion status on the total PVDF crystallinity (X_{c}); Piezoelectric nanocomposite fibrous membranes consisting of polymer polyvinylidene fluoride (PVDF) as matrix and incorporating 1D carbon nanotubes (CNTs) and 2D graphene oxide (GO) were prepared using an electrospinning process. The influence of the filler type, loading, and dispersion status on the total PVDF crystallinity (F_{β}); the volume fraction of β phase in the samples (v_{β}); and the piezoelectric coefficient d_{33} were investigated. The V_{β} is used to assess the formation of β phase for the first time, which considered the combined influence of fillers on X_{c} and F_{β}, and is more practical than other investigations using only F_{β} for the assessment. The inclusion of all types of carbon fillers had resulted in a considerable reduction in the X_{c} compared with the neat PVDF, and the X_{c} decreased with the CNT loading while increased with the GO loading. The addition of CNT and GO had also reduced the F_{β} compared with the neat PVDF, and F_{β} increased with CNT loading while decreased as GO loading increased. The v_{β} is significantly reduced by the addition of CNT and GO, while v_{β} decreases with CNT and GO loading increases. Since the calculation of V_{β} has considered the combined influence of fillers on X_{c} and F_{β}, both of which were reduced by incorporating CNT and GO, the reduction of v_{β} was expected. The v_{β} of the PVDF/CNT composites were higher than that of the PVDF/GO composites. Although it is generally anticipated that d_{33} increases with v_{β}, it is observed that in the presence of CNT, d_{33} is dominated by the increase in electric conductivity of the composites during and after the electrospinning process, giving rise to transport of charges, produced by β crystals within the fiber to the surface of the sample. In addition, the 1D CNTs may have promoted the orientation of β crystals in the d_{33} direction, therefore, enhancing the d_{33} of the composites despite the hindrance of the β-phase formation (i.e., the reduction of v_{β}). Adding CNTs can also improve piezoelectricity through interfacial polarization, which increases the dielectric constant of composite (mobile charges within CNTs facilitate composite polarization). CNT loadings higher than 0.01 wt.% are sufficient to outperform the neat PVDF, and d_{33} becomes 59.7% higher than the neat PVDF at 0.03 wt.% loading, but only GO loadings of 0.5 wt.% achieved comparable d_{33} to the neat PVDF; further increase in GO loading had resulted in a decline in d_{33}. The low conductivity of GO, the influence of flocculation, and the lower aspect ratio compared with CNT may result in lower electron transfer and less orientation of the β-phase polycrystalline. The d_{33} of the PVDF/CNT composites is higher than that of the PVDF/GO composites despite much higher loading of GO. This study aims to contribute to the development of PVDF nanocomposites in piezoelectric energy harvesting applications (e.g., self-powered biosensors and wireless sensor networks)

Polyhexamethylene Biguanide: Polyurethane Blend Nanofibrous Membranes for Wound Infection Control

Polyhexamethylene biguanide (PHMB) is a broad-spectrum antiseptic which avoids many efficacy and toxicity problems associated with antimicrobials, in particular, it has a low risk of loss of susceptibility due to acquired antimicrobial resistance. Despite such advantages, PHMB is not widely used in wound care, suggesting more research is required to take full advantage of PHMB’s properties. We hypothesised that a nanofibre morphology would provide a gradual release of PHMB, prolonging the antimicrobial effects within the therapeutic window. PHMB:polyurethane (PU) electrospun nanofibre membranes were prepared with increasing PHMB concentrations, and the effects on antimicrobial activities, mechanical properties and host cell toxicity were compared. Overall, PHMB:PU membranes displayed a burst release of PHMB during the first hour following PBS immersion (50.5–95.9% of total released), followed by a gradual release over 120 h (≤25 wt % PHMB). The membranes were hydrophilic (83.7–53.3°), gradually gaining hydrophobicity as PHMB was released. They displayed superior antimicrobial activity, which extended past the initial release period, retained PU hyperelasticity regardless of PHMB concentration (collective tensile modulus of 5–35% PHMB:PU membranes, 3.56 ± 0.97 MPa; ultimate strain, >200%) and displayed minimal human cell toxicity (<25 wt % PHMB). With further development, PHMB:PU electrospun membranes may provide improved wound dressings

Understanding gas transport mechanisms in shale gas reservoir: Pore network modelling approach

This report summarizes the recent findings on gas transport mechanisms in shale gas reservoir by pore network modelling. Multi-scale pore network model was developed to accurately characterize the shale pore structure. The pore network single component gas transport model was established considering the gas slippage and real gas property. The gas transport mechanisms in shale pore systems were elaborated on this basis. A multicomponent hydrocarbon pore network transport model was further proposed considering the influences of capillary pressure and fluid occurrence on fugacity balance. The hydrocarbon composition and pore structure influences on condensate gas transport were analyzed. These results provide valuable insights on gas transport mechanisms in shale gas reservoir.Cited as: Song, W., Yao, J., Zhang, K., Yang, Y., Sun, H. Understanding gas transport mechanisms in shale gas reservoir: Pore network modelling approach. Advances in Geo-Energy Research, 2022, 6(4): 359-360. https://doi.org/10.46690/ager.2022.04.1

Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 IOP Publishing Ltd.A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 µm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt–Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode. The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt–Ir coil electrode. Thermal annealing of the CNT fiber at 250 °C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 µM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt–Ir sensor.Brunel University, the Royal Society and the National Institute of Health

Characteristics Analysis of High Mechanical Strength Gymnastic Leather and Its Producing Process Optimization

Content: With the development of China sports, researches related to sports leather should be paid attention because they usually required higher strength than commonly used leather. In this paper, we focus on the production of gymnastics leather. In gymnastics, the athlete's hand will have high intensity contact with the balance bar, so the gymnastics leather is required to have high intensity performance. At the same time, in order to comply with the ornamental function, gymnastics leather is required to be light color. In this research, glutaraldehyde was used as the main tanning agent, while acrylic polymer and synthetic were used for retanning, in order to obtain high strength, environmentally friendly white gym leather. The shrinkage temperature and mechanical properties of tanned leather were determined and analyzed to determine the suitable tanning agent. Besides, other properties including softness, gas permeability, water permeability, flexing resistance and yellowing-resistance were also measured for selecting proper production process. Therefore, gymnastics leather with ideal performance can be prepared by this method, and the leather conforms to the practical application standard. In addition, the research has guiding significance and application prospect for high strength chrome-free tanned leather. Take-Away: Aldehyde tanning agents and retanning agents, which can be used for gymnastics leather making, were evaluated and selected to achieve ideal effect of finish leather. This research is meaningful to produce not only gymnastics leather but also other sporty leather which require high strength