A nanogenerator (NG) is an energy harvester device that converts mechanical energy into electrical energy on a small scale by relying on physical changes. Piezoelectric semiconductor materials play a key role in producing high output power in piezoelectric nanogenerator. Low cost, reliability, deformation, and electrical and thermal properties are the main criteria for an excellent device. Typically, there are several main types of piezoelectric materials, zinc oxide (ZnO) nanorods, barium titanate (BaTiO₃) and lead zirconate titanate (PZT). Among those candidate, ZnO nanorods have shown high performance features due to their unique characteristics, such as having a wide-bandgap semiconductor energy of 3.3 eV and the ability to produce more ordered and uniform structures. In addition, ZnO nanorods have generated considerable output power, mainly due to their elastic nanostructure, mechanical stability and appropriate bandgap. Apart from that, doping the ZnO nanorods and adding doping impurities into the bulk ZnO nanorods are shown to have an influence on device performance. Based on findings, Ni-doped ZnO nanorods are found to have higher output power and surface area compared to other doped. This paper discusses several techniques for the synthesis growth of ZnO nanorods. Findings show that the hydrothermal method is the most commonly used technique due to its low cost and straightforward process. This paper reveals that the growth of ZnO nanorods using the hydrothermal method has achieved a high power density of 9 µWcm⁻².

Traditional copper-based planar antennas have traditional disadvantages for wearable applications because of poor flexibility, deteriorated signal under deformation, expensive and environmental problems. To solve these issues, graphene has been proposed as a radiating material with high electrical conductivity, great flexibility, and the possibility of being printed on low-cost textile/paper substrates. In this study, graphene was used as a conductive material in an a two-port MIMO antenna for wearable smart communication. The graphene MIMO wearable antenna is printed on Jeans with a dielectric constant of 1.67, and an overall dimension of 35 × 55 mm³. The antenna operates in a multiband mode within the 5G sub-6 GHz spectrum, covering two distinct frequency ranges of 3.1–4.3 GHz and 4.9–6.0 GHz. This makes it a strong candidate for wearable 5G sub-6 GHz terminals, body-centric wireless communication systems, and short-range WLAN/ISM-based smart wearable devices. In addition, higher-order resonant bands at 8.25–9.4 GHz and 10.82–14.4 GHz are observed, indicating that the proposed design inherently exhibits wideband characteristics in the X-band region. The graphene is highly electrically conductive being 4.02 × 10⁵ S/m. The SAR analysis was carried out for the entire bandwidth, and it can be seen that energy absorption tends to be more restricted by increasing the skin depth (SC and OC) with higher frequency because of the dependence of dielectric properties on frequency. The maximum measured SARs are quite low below the ICNIRP safety limits 0.84 W/kg averaged over 10 g of tissue at an input power of 0.5 W, and hence it indicates that the proposed graphene-based MIMO configuration is a suitable solution for long-term wearable applications as it does not impose any health threats to the user.

Development and design of wearable textile antenna on various fabric substrate for unlicensed ultra-wideband applications

The acoustical requirements in terms of intelligibility and liveliness are dissimilar for both of sounds-recitation and speech on religious subjects at UTeM mosque. To attain an overall satisfactory acoustical performance, it is significant to find an optimum Reverberation Time (RT) and the best directivity, which is the major factors affecting intelligibility and liveliness. This experiment is conduct to gauge the effect of RT by making it a variable, while keeping other factors as non-variable and fulfilling ideal conditions for maximum intelligibility. Bearing in mind, the acoustical problems always occurred in any communication building. To improve the problem, this paper presents the new idea of improvement by using biodegradable sound absorber materials which is the mixture of dried rice straw and kapok.