Search

Abstract Ferroelectric BaBi4Ti4O15 was prepared using solid-state calcination at 950 °C for four hours. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy were utilized to understand its microstructure and other structural aspects. Particle size was around

Abstract This study presents a novel approach to fabricating interdigitated capacitive (IDC) touch sensors using graphite-based pencils on a wood substrate. The sensors were designed to detect touches and pressure variations, offering a cost-effective and environmentally friendly solution for sensor fabrication. The fabrication process involved abrasion of graphite pencils on a wooden substrate to create conductive traces, followed by the integration of interdigitated electrode structures. Capacitance variations resulting from touch interactions were investigated to calibrate sensor responses for tailored tasks. The sensitivity of the sensor was found to be 1.2 pF/kPa, highlighting its responsiveness to pressure variations. Additionally, the sensors were interfaced with an Arduino Uno microcontroller board to demonstrate practical applications, such as replicating arrow key functionality. Additionally, the sensors exhibit sensitivity to environmental factors, with the relative change in capacitance increasing from 0.1 to 0.65 as relative humidity ranges from 30 to 90%. Furthermore, variations in temperature from 30 to 60ºC result in a relative change in capacitance increasing to approximately 0.5. The results indicate the feasibility and versatility of using wood-based substrates and graphite-based pencils for fabricating IDC touch sensors, offering promising prospects for sustainable and accessible sensor technology.

Abstract Textile industry dye effluent contains a mixture of different kinds of dyes. Many times, photocatalysis is targeted as a solution for the treatment of dye effluent from the textile industry. Many researches have been published related to the photocatalysis of single textile dyes but in the real-world scenario, effluent is a mixture of dyes. Magnesium oxide (MgO) is used as a photocatalyst to treat a mixture (binary solution) of Methylene blue (MB) and Methylene violet (MV) along with individual MB and MV dyes in this article. MgO shows remarkable photocatalytic activity at about 93 and 88% for MB and MV dye in binary solution within 135 min. Furthermore, to study the influence of process parameters, experiments are designed with the help of the central composite design (CCD), and Response surface methodology (RSM) is used to study the interactions between parameters. For this study, five parameters are selected i.e., Photocatalyst dosage, initial concentration of both dyes, time of exposure to the light source, and pH of the binary solution. The photocatalytic process is also optimized and finally optimization of process parameters is validated with an experiment. The result of the validation experiment is very close to the predicted photocatalytic activity.

Abstract Electrowetting behaviour for carbon nanotubes (CNT) grown on stainless steel mesh was investigated. The effect of temperature, time, and applied bias voltage on the contact angle of water droplets was studied. The impact of temperature variation on contact angle was also performed for the temperature ranging from 25 to 70 °C. A decrement of contact angle by 68% was observed for the mentioned range indicating a transition from a hydrophobic to hydrophilic nature. A similar trend was observed on the application of electric potential to the CNT-modified stainless-steel mesh ranging from 0 to 8 V with a transition of contact angle from 146 to 30 deg respectively. A comparative analysis for the contact angle variation with time for CNT-coated mesh and uncoated mesh was performed for 180 min. It is observed that uncoated mesh shows a reduction in contact angle to 0 deg with time while the CNT coated mesh shows surplus hydrophobicity with a 2 deg decrement in the extent of time. CNT-modified mesh successfully absorbs 95% of rhodamine B (RB) dye and detergent from water in 10 cycles.

With the improvement in people’s quality of life, the requirements for health and safety are also increasing. While many wearable devices are available, those wearable devices specifically designed for the safety of night workers have yet to be effectively utilized. A survey conducted with 100 night workers revealed that they have expressed concerns about their safety and that of their colleagues due to lack of visibility while working on the road at night. To address this issue, a wearable electromagnetic energy generator was designed as a permanent solution to increase the visibility of night workers by illuminating LEDs and reduce the discomfort associated with wearable devices. The generator can be integrated with uniforms and converts the kinetic energy generated by the human body during work into electrical power. The generator achieved a maximum output power of 4.28 mW under 2.8 Hz, with a power density is 51.56 μW/cm3. The LED brightness driven by the generator reached 218 Lux. To ensure user customization, the Living Lab strategy was employed, allowing direct user participation during the development process and incorporating improvements based on their feedback. After gathering feedback from the workers, the uniform was redesigned and revised multiple times. Ultimately, the product received high satisfaction scores and was successfully delivered to local municipalities. This paper details a comprehensive study covering the process from needs survey to product design.

Abstract The fabrication of a Poly (vinylidene fluoride) membrane (PVDF) and ceramic-assisted bismuth vanadate-polyvinylidene fluoride (BiVO4-PVDF) composite membrane was achieved through the utilization of the electrospinning technique. The composition and structure of the fabricated membranes were characterized by X-ray powder diffraction, Raman analysis, scanning electron microscopy, Thermo gravimetric analyzer, Fourier transform infrared spectroscopy, and UV–Vis spectroscopy techniques. The prepared polymeric membranes were then utilized for catalytic investigation and to explore, how structure affects catalytic activity using 5 mg/L, 10 mL methylene blue (MB) dye solution. Ultrasonication, visible light irradiation, and the combination were used to study piezocatalysis, photocatalysis, and piezo-photocatalysis, moreover, degradation intermediates were also explored using scavengers. Electrospun BiVO4-PVDF (BV-PVDF) composite has been found to have better piezocatalytic and photocatalytic properties than PVDF. The experimental findings reveal that the composite of BiVO4-PVDF demonstrates the highest efficiency in dye degradation, achieving a maximum degradation rate of 61% within a processing time of 180 min. The rate of degradation was calculated to be 0.0047 min−1, indicating a promising potential for the composite in the field of dye degradation.

Abstract The mechanochemical ball milling followed by heating at 650 °C for 5 h successfully produced the single-phase Bi2VO5.5 powder. Catalytic activity for methylene blue dye degradation was investigated. Raman spectroscopy and X-ray diffraction were used to confirm the phase formation. The sample’s charge carrier transportation behavior was ascertained using time-dependent photocurrent analysis. The piezo-photocatalysis experiment yielded a 63% degradation efficiency for the ball-milled Bi2VO5.5 sample. The pseudo-first-order kinetics of the piezo-photocatalytic dye degradation are discerned, and the significant k value of 0.00529 min−1 is achieved. The scavenger test declares the h+ radical is the predominant active species during the piezo-photocatalysis experiment. Vigna radiata seeds were used in a phytotoxicity test to evaluate the germination index. The mechanochemical activation method facilitates reactions by lowering reaction temperature and time. The effect of improved piezo-photocatalytic efficiency on the ball-milled Bi2VO5.5 powder is an unexplored area, and we have attempted to investigate it. Here, ball-milled Bi2VO5.5 powder achieved improved dye degradation performance.

Abstract A thermoregulating smart textile based on phase change material (PCM) polyethylene glycol (PEG) was prepared by chemically grafting carboxyl-terminated PEG onto cotton. Further deposits of graphene oxide (GO) nanosheets were made on the PEG grafted cotton (PEG-g-Cotton) to improve the thermal conductivity of the fabric and to block harmful UV radiation. The GO-PEG-g-Cotton was characterized by Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and field emission-scanning electron microscopy (FE-SEM). With an enthalpy of 37 and 36 J/g, respectively, the DSC data revealed that the functionalized cotton's melting and crystallization maxima occurred at 58 °C and 40 °C, respectively. The thermogravimetric analysis (TGA) presented that GO-PEG-g-Cotton was thermally more stable in comparison to pure cotton. The thermal conductivity of PEG-g-Cotton increased to 0.52 W/m K after GO deposition, while pure cotton conductivity was measured as 0.045 W/m K. The improvement in the UV protection factor (UPF) of GO-PEG-g-Cotton was observed indicating excellent UV blocking. This temperature-regulating smart cotton offers a high thermal energy storage capability, better thermal conductivity, thermal stability, and excellent UV protection.

0.5Ba (Zr0.2Ti0.8)O3-0.5(Ba0.7Sr0.3)TiO3 (BST-BZT) ceramic composition is known for exihibiting electrical properties. The present study brings out the prospective approach of utilizing well known BST-BZT ceramic composition for water cleaning application via piezocatalysis, photocatalysis and piezo-photocatalysis process. For this, BST-BZT ceramic composition was synthesized through solid state route reaction method and was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Methylene Blue (MB) a cationic dye was used as a representative organic pollutant, where the maximum degradation was observed in piezo-photocatalysis process (∼92%) followed by photocatalysis process (∼82%) and piezocatalysis process (∼65%) in 240 min. Furthermore, the degradation of MB dye was examined under solar light irradiation in order to assess the potential of the BST-BZT ceramic composition. A study on the BST-BZT ceramic composition's photocatalytic activity in an indoor setting was also conducted. Finally, the phytotoxicity level of “Vigna radiata” seeds was examined to determine the extent of MB dye breakdown and its subsequent usage.

Abstract Finite element studies were conducted on 0.5Ba(Zr0.2 Ti0.8) O3–0.5(Ba0.7 Ca0.3)TiO3 (BCZT) piezoelectric particles embedded in polyethylene matrix to create a piezocomposite having a positive and negative Poisson's ratio of −0.32 and 0.2. Polyethylene with a positive Poisson's ratio is referred to as non-auxetic while those with negative Poisson's ratio are referred to as auxetic or inherently auxetic. The effective elastic and piezoelectric properties were calculated at volume fractions of (4%, 8% to 24%) to study their sensing and harvesting performance. This study compared lead-free auxetic 0–3 piezocomposite for sensing and energy harvesting with non-auxetic one. Inherently auxetic piezocomposites have been studied for their elastic and piezoelectric properties and improved mechanical coupling, but their sensing and energy harvesting capabilities and behavior patterns have not been explored in previous literatures. The effect of Poisson's ratio ranging between −0.9 to 0.4 on the sensing and energy harvesting performance of an inherently auxetic lead free piezocomposite composite with BCZT inclusions has also not been studied before, motivating the author to conduct the present study. Auxetic piezocomposite demonstrated an overall improvement in performance in terms of higher sensing voltage and harvested power. The study was repeated at a constant volume fraction of 24% for a range of Poisson's ratio varied between −0.9 to 0.4. Enhanced performance was observed at the extreme negative end of the Poisson's ratio spectrum. This paper demonstrates the potential improvements by exploiting auxetic matrices in future piezocomposite sensors and energy harvesters.

The presence of toxic compounds in waste leads to unfavorable hazardous properties, there is an urgent urge for the remediation of environmental contamination. This work focuses on the removal of organic pollutants from the water. Piezocatalytic properties of transparent glass nanocomposites of Bi2ZnB2O7 (BBZO) were studied for water-cleaning application. Melt quenching followed by heat treatment of fabricated glass-nanocomposites were able to degrade different organic dyes. To study the microstructure of the samples under consideration, X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) were performed. To get the elemental composition of the glass nanocomposite samples, XPS (X-ray photoelectron spectroscopy) was utilized. Methylene blue (MB) dye was used as a model dye for degradation, and it is found that heat-treated glass nanocomposite sample at 475 °C for 1 h (HT/475 °C/1hr) gives maximum dye degradation of 78% under 240 min of ultrasonication with a degradation rate of 0.0065min−1. Furthermore, an obtained by-product from degraded dye was used to experiment to study phytotoxicity assessment using brown gram seeds and it has been found that treated water with BBZO HT/475 °C/1hr sample gives less phytotoxicity of water (Germination Index is found to be 88%).

This study comprises the combined effect of piezocatalytic and photocatalytic activity to obtain improved piezo-photocatalytic dye degradation efficiency in visible light. Single-phase Bi2VO5.5 powder was prepared through solid-state synthesis at 750 °C in 8 h. Time-dependent photocurrent responses were conducted to understand the phenomenon of charge carrier transport in visible light. Bi2VO5.5 powder sample demonstrated high photocatalytic efficiency and good reusability possessing a bandgap value of 2.13 eV. Bi2VO5.5 powder sample attained ∼70% and ∼58% degradation efficiency during photocatalysis and piezocatalysis respectively. The piezo-photocatalytic methylene blue dye attained ∼82% degradation efficiency in 240 min duration of visible light illumination. The scavenger test depicted holes (h+) as the principal active species in the piezo-photocatalytic dye degradation. There incurred no severe loss in photocatalytic efficiency even after 4 cycles which proclaims the reusability of the Bi2VO5.5 powder sample. A study on the kinetic rate constant with varying dye concentrations was conducted. With varied dye concentration of 5, 10, 15 mg/L, the kinetic rate constant obtained was 0.00528, 0.0030, and 0.00125 min−1, respectively. Germination index was found through a phytotoxicity test using vigna radiata seeds. Here visible light along with mechanical energy has been used to achieve higher MB dye degradation efficiency through piezo-photocatalysis.

Abstract A single‐phase Bi2VO5.5 powder is formed effectively through a mechanochemical ball milling approach at 650 °C in 5 h and its photocatalytic performance on methylene blue dye is explored. X‐ray diffraction and Raman spectroscopy analytical instruments are utilized to confirm the phase formation. The evident presence of irregular‐shaped grains is affirmed using a scanning electron microscope. To ascertain the chemical condition of the components present, the Bi2VO5.5 powdered sample undergo an X‐Ray photoelectron spectroscopy investigation. The sample is analyzed using a time‐dependent photocurrent to discern its charge carrier transportation behavior. A photocatalytic study using Bi2VO5.5 powder produced through the mechanochemical ball milling method has not been explored till now. The efficacy of the ball‐milled Bi2VO5.5 powder to attain enhanced photocatalytic efficiency which hasn't been investigated till now, is explored. The ball‐milled Bi2VO5.5 sample achieved 70% degradation efficiency when performing the photocatalysis investigation. The photocatalytic dye degradation discerns pseudo‐first‐order kinetics and achieves a notable k value of 0.00636 min−1. The scavenger test indicates that h+ radicals are the prominent active species during the photocatalysis experiment. The germination index is determined by conducting a phytotoxicity test with the use of Vigna radiata seeds. Here ball‐milled Bi2VO5.5 powder attains enhanced dye degradation efficiency.

Abstract This study focuses on analyzing the poling effect of BaBi4Ti4O15 (BBT) on the basis of photo and piezo‐catalysis performance. BBT powder is prepared via a solid state reaction followed by calcination at 950 °C for 4 h. BBT is characterized by an X‐ray diffractometer, scanning electron microscopy, Raman spectroscopy, and X‐ray photoelectron spectroscopy. The optical bandgap of BBT is evaluated with the help of Tauc's plot and found to be 3.29 eV, which comes in the photon energy range of ultra‐violet radiation. BBT powder is poled by using Corona poling in the presence of 2 kV mm−1 of electric field. An aqueous solution of methyl blue (MB) dye in the presence of UV radiation is used to evaluate the photo/piezocatalysis performance. Photocatalysis, piezocatalysis, and photo–piezo catalysis degradation efficiencies of poled and unpoled BBT powder are tested for 120 min of UV light irradiation. Photo–piezocatalysis shows degradation efficiencies of 62% and 40% for poled and unpoled BBT powder, respectively. Poling of BBT powder shows significant enhancement in degradation performance of MB dye in aqueous solution. Scavenger tests are also performed to identify reactive species.

Abstract In the present numerical simulation work, effective elastic and piezoelectric properties are calculated and a comparative study is conducted on a cement matrix‐based piezocomposite with 0–3 and gyroid triply periodic minimal surface (TPMS) inclusions. The present study compares the effective properties of different piezoelectric materials having two different types of connectivity of the inclusions namely, 0–3 inclusions where the inclusions are physically separated from each other and are embedded within the matrix and the second one is TPMS inclusions having interpenetrating phase type connectivity. Effective properties are calculated for four different materials at five different volume fractions namely, 10%, 15%, 20%, 25%, and 30% volume fractions of inclusion by volume. In terms of effective properties and direct piezoelectric effect, TPMS piezocomposite is found to perform better compared to 0–3 piezocomposite. Lead‐free piezoelectric material 0.5Ba(Ca0.8Zr0.2)O3 − 0.5(Ba0.7Ca0.3)TiO3 demonstrates better performance compared to all other material inclusions studied. The present study attempts to highlight improved piezoelectric effective properties of lead‐free material‐based piezocomposites with TPMS inclusions.

Abstract Piezoelectric materials play an important role in powering nano and microelectromechanical systems. However, these are often limited by their low sensing, actuation, and power outputs. This study proposes a novel poling direction arrangement theoretically in the piezoelectric materials which enhances the output parameters drastically. The poling angle was graded from bottom to top surface of element in linear fashion which helps in utilizing the bending and shear stresses efficiently. The sensing, actuation and energy harvesting performance of Pb[ZrxTi1‐x]O3 in graded mode was compared with those obtained from operating in transverse and shear modes. It was found from finite element simulations that a maximum sensing voltage of 11.85 V was been obtained in graded mode which was around 15 times higher than that obtained in shear mode. Likewise, a maximum strain of 8.2 μm/m and a tip displacement of 34.3 μm was observed in the graded mode. Eventually, the maximum power of 0.12 W was harvested from graded mode harvester followed by shear mode harvester where only : 1.6 × 10−3 W could be harvested. However, the associated challenge with such study is the fabrication and graded poling of piezoelectric which still is an unexplored research area for scientific fraternity.

This study covers a self-powered wireless communication system that is powered using a piezoelectric energy harvester (PEH) in a shoe. The lead-zirconate-titanate (PZT) ceramic of the PEH was coated with UV resin, which (after curing under UV light) allowed it to withstand periodic pressure. The PEH was designed with a simple structure and placed under the sole of a shoe. The durability of the PEH was tested using a pushing tester and its applicability in shoes was examined. With periodic compression of 60 kg, the PEH produced 52 μW of energy at 280 kΩ. The energy generated by the PEH was used to power a wireless transmitter. A step-down converter with an under-voltage lockout function was used to gather enough energy to operate the wireless transmitter. The transmitter can be operated initially after walking 24 steps. After the transmitter has been activated, it can be operated again after 8 steps. Because a control center receives signals from the transmitter, it is possible to check the status of workers who work outside at night or mostly alone, to detect emergencies.

Abstract This study proposes the design of a micro‐spiral‐shaped piezoelectric energy harvester that scavenges energy from blood pressure variation in the cardiac cycle. The harvester can be a miniaturized perennial source of power that could even eliminate the need for replacement of conventional batteries used in current pacemaker technology. The concept of a 25 µm thin spiral‐based piezoelectric energy harvester with a diameter of 6 mm satisfying the dimensional constraints has been proposed. A number of lead‐free materials have been used along with Pb[ZrxTi1−x]O3 (PZT‐5A) to compare the performance. The harvester has been designed in such a way that the natural frequency of the structure remains in the range of 1.1–1.3 Hz, which is equivalent to 66–78 heart beats min−1 of humans. The obtained alternating electric current from piezoelectric materials is converted into direct current. The maximum open‐circuit voltage obtained is ≈0.9 V, which is not sufficient for charging a pacemaker battery. Therefore, boost converter circuit is employed to step up the voltage. It is found that K0.475Na0.475Li0.05(Nb0.92Ta0.05Sb0.03)O3 (KNLNTS) has the best performance as compared to other materials under study. The boosted voltage obtained from KNLNTS is ≈6 and ≈7 V for 80 and 90% duty cycle, respectively, which are sufficient for pacemaker battery charging.

In this article, the performance of various piezoelectric materials is simulated for the unimorph cantilever-type piezoelectric energy harvester. The finite element method (FEM) is used to model the piezolaminated unimorph cantilever structure. The first-order shear deformation theory (FSDT) and linear piezoelectric theory are implemented in finite element simulations. The genetic algorithm (GA) optimization approach is carried out to optimize the structural parameters of mechanical energy-based energy harvester for maximum power density and power output. The numerical simulation demonstrates the performance of lead-free piezoelectric materials in unimorph cantilever-based energy harvester. The lead-free piezoelectric material K0.5Na0.5NbO3-LiSbO3-CaTiO3 (2 wt.%) has demonstrated maximum mean power and maximum mean power density for piezoelectric energy harvester in the ambient frequency range of 90–110 Hz. Overall, the lead-free piezoelectric materials of K0.5Na0.5NbO3-LiSbO3 (KNN-LS) family have shown better performance than the conventional lead-based piezoelectric material lead zirconate titanate (PZT) in the context of piezoelectric energy harvesting devices.

This paper examines the selection and performance evaluation of a variety of piezoelectric materials for cantilever-based sensor applications. The finite element analysis method is implemented to evaluate the relative importance of materials properties such as Young's Modulus (E), piezoelectric stress constants (e31), dielectric constant (ε) and Poisson's ratio (υ) for cantilever-based sensor applications. An analytic hierarchy process (AHP) is used to assign weights to the properties that are studied for the sensor structure under study. A technique for order preference by similarity to ideal solution (TOPSIS) is used to rank the performance of the piezoelectric materials in the context of sensor voltage outputs. The ranking achieved by the TOPSIS analysis is in good agreement with the results obtained from finite element method simulation. The numerical simulations show that K0.5Na0.5NbO3–LiSbO3 (KNN–LS) materials family is important for sensor application. Young's modulus (E) is most influencing material's property followed by piezoelectric constant (e31), dielectric constant (ε) and Poisson's ratio (υ) for cantilever-based piezoelectric sensor applications.