Screen Printing Technique Research Articles

A 3D printed pressure sensor based on a bossed diaphragm with straight-annular grooves

Purpose To supply temporary pressure testing devices with favorable performance for emergency environments, this paper aims to present a pressure sensor with a central boss and straight-annular grooves. The structural feature is modeled and optimized by neural network-based method, and the device prototype is fabricated by 3D printing techniques. Design/methodology/approach The study initially compares mechanical properties of the proposed structure with two conventional designs using finite element analysis. The impacts from structural dimensions on sensor performance are modeled using a Backpropagation neural network and optimized through genetic algorithms. The sensing diaphragm is fabricated using stereolithography (SLA) 3D printing, while the piezoresistors and necessary interconnects are realized with screen printing techniques. Findings The experimental results demonstrate that the fabricated sensor exhibits a sensitivity of 2.8866 mV/kPa and a nonlinearity of 6.81% within the pressure range of 0–100 kPa. This performance is an improvement of 118% in sensitivity and a decrease of 54% in nonlinearity compared to flat diaphragm structure, highlighting the effectiveness of proposed diaphragm configuration. Originality/value This research offers a holistic methodology that encompasses the structural design, optimization and fabrication of pressure sensors. The proposed diaphragm and corresponding modelling method can provide a practical approach to enhance the measurement capabilities of pressure sensors. By leveraging SLA printing for diaphragm and screen printing for circuit, the prototype can be produced in a timely manner.

Rheological investigations on frequency selective surface carbon composite microwave absorber.

A high-performance stealth platform is one of the crucial requirements in defence technology that could practically be realized by building effective microwave frequency selective surface (FSS) absorbers. Herein, we report the design and manufacturing of an absorber by tuning the rheology of cell architecture. Initially, a fan-shaped cell (10.4 mm2) was designed for its surface and bulk rheology. The FSS overlayer composition was investigated using SEM, EDX, and XRD and tuned for 0.25% carbon: 1.5% silver to achieve the ink resistivity ∼255 Ω □-1. The bulk rheology was optimized for air (Roha) spacer (thickness ∼2.8 mm), interlayer dielectrics (0.2 mm each), carbon composition (5%), and cell dimension (10.2 mm). Analyses are presented for absorption loss (RC, dB), bandwidth (GHz), resonance dispersion, and constitutive (ε, μ) parameters, compounded with an equivalent circuit model with the settings R = 273.55 Ω, L = 2.25 nH, C = 0.057 pF and the Fabry-Perot reactance mode@10 GHz. The bi-modal response was investigated for induced polarization, electromagnetic fields, volume power distribution, and angular (Θ = 0°-50°) and rotational stability (Φ = 0°-90°) against TE/TM incidences. The FSS pattern was implemented using a screen printing technique to fabricate a prototype absorber and subjected to the free space measurements in an anechoic chamber. The prototype behaviour was found to be commensurate with the simulated performance, thereby achieving a figure of merit of RC ∼-25 dB@10 GHz, accessible bandwidth 4 GHz (in X band) by using the thickness of 0.057 λ0. Details are presented in this study.

Nanobinders advance screen-printed flexible thermoelectrics.

Limited flexibility, complex manufacturing processes, high costs, and insufficient performance are major factors restricting the scalability and commercialization of flexible inorganic thermoelectrics for wearable electronics and other high-end cooling applications. We developed an innovative, cost-effective technology that integrates solvothermal, screen-printing, and sintering techniques to produce an inorganic flexible thermoelectric film. Our printable film, comprising Bi2Te3-based nanoplates as highly orientated grains and Te nanorods as "nanobinders," shows excellent thermoelectric performance for printable films, good flexibility, large-scale manufacturability, and low cost. We constructed a flexible thermoelectric device assembled by printable n-type Bi2Te3-based and p-type Bi0.4Sb1.6Te3 films, which achieved a normalized power density of >3 μW cm-2 K-2, ranking among the highest in screen-printed devices. Moreover, this technology can be extended to other inorganic thermoelectric film systems, such as Ag2Se, showing broad applicability.

Modification of glass screen printed electrodes with graphene quantum dots for enhanced power output in miniaturized microbial fuel cells

This paper demonstrates screen-printing technique, Glass Screen printed (GSP) on glass layer with Graphene Quantum Dots (GQDs) via drop casting approach to manufacture electrodes for Miniaturized Microbial Fuel Cells (MMFCs). MMFCs are viable options to sustainably operate low-power devices such as sensors, implantable medical devices, etc. However, the technology is still not fully mature for practical applications due to limitations of output power. Materials and design improvements are required for decreasing internal resistance for better electron transfer and improving overall performance. In this work the electrodes manufactured by GSP technique, and anode modified by GQD was tested in MMFC using RO wastewater. It was found that the GQDs increased the surface area to improve electron transfer kinetics at the anode. As a result, GQDs-based GSPEs showed 7.4 times higher power output 332 nW/cm2 compared to its unaltered electrode which displayed a power output of 44.8 nW/cm2. Electrodes made by GSP technique are more durable and less susceptible to biofouling and corrosion compared to conventional methods. The modified anodes further showed sustained output for long term operation.

A Novel Frequency-Selective Surface-Enhanced Composite Honeycomb Absorber with Excellent Microwave Absorption.

Multifunctional structures with excellent wave-absorbing and load-bearing properties have attracted much attention in recent years. Unlike other wave-absorbing materials, honeycomb wave-absorbing materials have appealing radar absorption and mechanical properties. However, the existing honeycomb wave-absorbing materials have problems such as narrow absorption band and poor compression resistance. In this study, a novel frequency selective surface-enhanced composite honeycomb absorbers (FSS-CHAs) are fabricated by combining a honeycomb structure with wonderful load-bearing capacity and FSS through screen-printing and inlay-locking techniques. After reflectivity measurements, the effective absorption band (RL < -10 dB) of CHA is 6.25-17.47 GHz and a bandwidth of 11.22 GHz, the effective absorption band of the FSS-CHA is 3.96-18 GHz and a bandwidth of 14.04 GHz, 25.13% improvement compared to the CHA, the mechanism of wave absorption is explained using transmission line theory. The simulation results show that the wide bandwidth is due to the different absorption mechanisms of FSS-CHA at low and high frequencies. The compression test shows that the compression strength of FSS-CHA is 17.10 MPa. In addition, FSS-CHA has a low cost of only USD 270.7/m2. This study confirms the possibility of combining FSS with radar-absorbing honeycombs, which provides a reference for the design of future broadband wave-absorbing structures, offers a novel approach to integrating FSS with CHA, and aims to optimize their efficacy and utility in stealth technology.

Screen-Printed PVDF Piezoelectric Pressure Transducer for Unsteadiness Study of Oblique Shock Wave Boundary Layer Interaction.

Shock wave boundary/layer interactions (SWBLIs) are critical in high-speed aerodynamic flows, particularly within supersonic regimes, where unsteady dynamics can induce structural fatigue and degrade vehicle performance. Conventional measurement techniques, such as pressure-sensitive paint (PSP), face limitations in frequency response, calibration complexity, and intrusive instrumentation. Similarly, MEMS-based sensors, like Kulite® sensors, present challenges in terms of intrusiveness, cost, and integration complexity. This study presents a flexible, lightweight polyvinylidene fluoride (PVDF) piezoelectric sensor array designed for high-resolution wall-pressure measurements in SWBLI research. The primary objective is to optimize low-frequency pressure fluctuation detection, addressing SWBLI's need for accurate, real-time measurements of low-frequency unsteadiness. Fabricated using a double-sided screen-printing technique, this sensor array is low-cost, flexible, and provides stable, high-sensitivity data. Finite Element Method (FEM) simulations indicate that the sensor structure also has potential for high-frequency responses, behaving as a high-pass filter with minimal signal attenuation up to 300 kHz, although the current study's experimental testing is focused on low-frequency calibration and validation. A custom low-frequency sound pressure setup was used to calibrate the PVDF sensor array, ensuring uniform pressure distribution across sensor elements. Wind tunnel tests at Mach 2 verified the PVDF sensor's ability to capture pressure fluctuations and unsteady behaviors consistent with those recorded by Kulite sensors. The findings suggest that PVDF sensors are promising alternatives for capturing low-frequency disturbances and intricate flow structures in advanced aerodynamic research, with high-frequency performance to be further explored in future work.

Enhancing Sensing Performance of SnO2-Based Gas Sensors Using Bismuth Ions As Catalytic Additives

Metal oxide semiconductor (MOS) based resistive-type gas sensors play a crucial role in monitoring and detecting various gases for a wide range of applications, from environmental monitoring to industrial safety. Among the various MOS materials, SnO2 has emerged as a prominent gas sensing material due to its high sensitivity, excellent stability, and low cost. In recent years, significant efforts have been directed towards further enhancing the performance of SnO2-based gas sensors. According to the gas sensing mechanism of resistive-type gas sensor, improving the receptor function can fundamentally modify the sensing performance to combustible gases. Surface functionalization using catalytic additives has been introduced as an effective approach to strengthen the receptor function of sensing material. In this study, Bismuth (Bi) ions are employed as one of foreign receptors to improve the performance of SnO2-based gas sensors due to their high catalytic activity. SnO2, Bi2O3-mixed SnO2, Bi-loaded SnO2 and Bi-doped SnO2 particles were successfully synthesized. XRD, SEM-EDS and N2 adsorption/desorption measurements were conducted to characterize the as-prepared samples. The results revealed that Bi2O3-mixed SnO2 and Bi-loaded SnO2 materials show similar crystal structure and specific surface area with pure-SnO2 NPs. Meanwhile, Bi2O3 particles were physically mixed with SnO2 nanoparticles in the Bi2O3-mixed SnO2 sample. For Bi-loaded SnO2 sample, no Bi2O3 particles are observed, and Bi ions are well dispersed onto the SnO2 surface. Additionally, Bi-doped SnO2 particles show significantly smaller crystallite size and a larger specific surface area than pure-SnO2 NPs, indicating that Bi ions were doped into SnO2 lattice during the Bi-doping process. Subsequently, thin-film gas sensors were fabricated using a screen-printing technique based on as-prepared materials, and gas sensing performance measurements were conducted from 200oC to 350oC. The results show that Bi-loaded and Bi-doped SnO2 sensors exhibit significantly higher sensitivity to C2H5OH than pure and Bi2O3-mixed SnO2 sensors. Generally, there are mainly two reaction pathways during C2H5OH oxidation, including dehydration to produce C2H4 and dehydrogenation to generate CH3CHO. According to the previous research, the oxidation of C2H5OH molecules on pure-SnO2 surface follows a large amount of dehydrogenation and partial dehydration. In this experiment, both Bi-loaded and Bi-doped SnO2 sensors exhibit comparable sensitivity to CH3CHO with C2H5OH accompanied by an extremely low response to C2H4, indicating that the oxidation of C2H5OH mainly depends on CH3CHO combustion. The results reveal that the catalytic activity of Bi ions improves the dehydrogenation process during C2H5OH oxidation on the SnO2 surface. Additionally, comparable sensitivity to all targeted gases is observed at 350oC for Bi-doped SnO2 sensor. The poor selectivity can probably be attributed to the modified electronic structure and chemical properties caused by the incorporation of bismuth ions into the SnO2 lattice, leading to overactive reactivity at higher temperature. Furthermore, Bi-loaded SnO2 sensor shows significantly lower sensitivity to CO, C7H8 and H2 than to C2H5OH at any operating temperature, illustrating excellent selectivity to C2H5OH. In conclusion, the dispersion of Bi ions onto the SnO2 surface improves sensitivity and selectivity to C2H5OH by accelerating dehydrogenation. This study provides valuable insights into the design and development of advanced gas sensing material with outstanding performance using catalytic additives.

Flexible electrochemical sensor based on N-doped helical carbon nanotubes coated manganese oxide nanoparticles for real-time monitoring of cellular hydrogen peroxide release

Electrochemical sensor is a sensitive and fast method to test hydrogen peroxide (H2O2) released from cancer cells. To map a clear understanding of the mechanisms during drug treatment of cancer, it is necessary to in-situ and real-time monitor of H2O2 content in the release process from cancer cells. Herein, N-doped helical carbon nanotubes (HCNTs) coated manganese oxide (MnO) nanoparticles (MnO@HCNTs) were prepared using a high-temperature molten salt method. The ratio of Mn salt to 2-methylimidazole was adjusted to optimize the Mn2+/Mn3+ ratio of the active center. The MnO@HCNTs were further modified on a polydimethylsiloxane (PDMS) based electrode printed by screen printing technique to build a flexible electrochemical sensor (MnO@HCNTs/PDMS). The presence of graphitic N increases the surface electron density, thereby enhancing the electrical conductivity of MnO@HCNTs/PDMS. Simultaneously, graphitic N triggers electronic arrangement in the Mn, leading to an increase in Mn-N coordination. Furthermore, the adsorption performance of MnO@HCNTs/PDMS for H2O2 increases with more N content, which may also enhance the electrocatalytic activity towards H2O2. The sensitivity of this sensor for H2O2 analysis was observed as 636.9 μA μM−1 cm−2 with a limit of detection as 2.6 nmol L−1 in a linear response range from 10.0 nmol L−1 to 1000.0 nmol L−1 and a fast response time of 1.2 s. Finally, the flexible MnO@HCNTs/PDMS was combined with a smart sensing system, which displayed the ability for highly sensitive real-time monitoring of drug-stimulated H2O2 that released from lung cancer cells A549 under the phorbol ester stimulation.

Enhancement of electrode surface hydrophilicity and selectivity with Nafion-PSS composite for trace heavy metal sensing in electrochemical sensors

BackgroundEffective electrochemical sensing requires optimal signal output value and sensitivity, which often pose a challenge due to their counter-intuitive relationship. In order to enhance both aspects, this study designs a modified screen-printed electrode (Nafion-PSS/SPE) comprising a composite formed by two sulfonate-rich polymers, namely Nafion and poly(sodium 4-styrenesulfonate) (PSS). The Nafion-PSS/SPE was utilized in the electrochemical determination of lead (Pb2+) and cadmium (Cd2+) via square wave anodic stripping voltammetry (SWASV). This innovative approach aims to improve detection limits and overall analytical performance in complex matrices. (84) ResultsThe addition of hydrophilic PSS positively improves surface wettability of Nafion-PSS/SPE, as confirmed by water contact angle analysis. Despite the improved wettability, the modified sensor maintains a high selectivity towards heavy metal ions. Cyclic voltammetry (CV) reveals a large electrochemically active surface area (ECSA) for cations (0.5646 cm2) and a relatively low ECSA for anions (0.3221 cm2). Under optimized conditions, the stripping responses for Pb2+ and Cd2+ exhibited linearity within the concentration ranges of 0.025–0.7 ppm and 0.0125–0.4 ppm, respectively. The detection limits achieved by the modified sensor are 6.478 ppb (Pb2+) and 5.277 ppb (Cd2+). The enhancement observed can be ascribed to the following factors, including presence of sulfonate ligands (Nafion and PSS), enhanced wettability (PSS), and surface selectivity (Nafion). Furthermore, even in the presence of interfering ions replicating the composition of effluent from the pesticide industry, the Nafion-PSS/SPE showcases remarkable selectivity for the target Pb2+ and Cd2+ ions. (148) SignificanceThis work presents a facile screen-printing technique that could be potentially adopted for batch production of heavy metal sensing devices. Besides, by scrutinizing the surface properties of the modified sensor, this work aims to provide insights on how the proposed modification approach can help to improve the sensor's detection performance. (50)

Facile fabrication of foldable electrospun nanofiber electrodes for electrodes for electronic biosensing

This study presents a rapid, sensitive and selective sensor based on electrospun nanofibers on laser-patterned electrodes, in which the laser micromachining process can directly fabricate the graphene electrode device for the electronical detection of glucose molecule. The layer of graphene film was formed on the glass substrate by a screen printing technique, and then the graphene electrodes can be fabricated by the ultraviolet (UV) nanosecond laser process with the wavelength of 355 nm. Based on the controlled the laser fluence and pulses, the electrode gap of 60 μm within the device can be fabricated. The polyvinyl alcohol (PVA) and glucose oxidase (GOD) composite nanofiber with weight percentage of 8% can be used by the electrospun process with used Glutaraldehyde(GA) steam for cross linking process. After that, it is blended with the conductivity of poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS), and the foldable nanofiber structures was made by electrospun process on the graphene electrode device. Finally, the electrical detection of graphene electrode device with the nanofibers at different concentrations of glucose can be measured, resulting in the linear variation is detecting the glucose concentration ranging form 0.01 to 3.12 mM. This work indicated that the low concentration and highly sensitive can be used for electronic biosensors

Triple-Mode Protection with Ln3+ Ion-Doped Core-Heptad-Shell Single Nanocrystals for High-Level Security Applications.

In this work, oleic acid (OA)-capped core-heptad-shell (CHS) nanocrystals (NCs) that exhibit multiple emissions achieved through downshifting and orthogonal upconversion are synthesized via layer-by-layer thermal decomposition. This method enables the downshifting process to be accommodated by doping ions in the inert space between two upconversion patterns (the core and fourth shell) and doping Ce/Tb or Ce/Eu ions in the NaGdF4 layer for the first time. These developed CHS NCs exhibit different emission colors via 980 and 800 nm orthogonal upconversion and downshifting emissions under 256 nm UV excitation in hexane solvent. Furthermore, surface-functionalized OA is removed using mild acid treatment. The resulting bare CHS NCs disperse well in water and exhibit 21.60-fold and 43.59-fold higher Ce/Tb and Ce/Eu luminescence intensities, respectively, than the OA-capped CHS NCs. These NCs are mixed with a carboxymethylcellulose (CMC) polymer in an aqueous medium to form a CMC-CHS NC gel. Invisible patterns and QR codes are printed on nonfluorescent paper using gels and screen-printing techniques. These patterns and QR codes exhibit three different emission colors under three different excitations. This method can be used for high-level anticounterfeiting applications.

Preparation of the scattering layer based on SnO2 nanocrystals for dye sensitized solar cell application

Abstract In this work, SnO2 paste was prepared based on (0.1 and 0.12 g) of SnO2 nanoparticles. The SnO2 film was deposited using Screen printing and doctor blade techniques, which it employed as scattering layer in Dye-Sensitized Solar Cell (DSSC). The crystal structure, morphology, and thermal stability of the paste were investigated using XRD, FE-SEM, and TGA techniques. The DSSC parameters were achieved to examining the effect of scattering layer on performance of DSSC. The results showed a crystalline structure predominantly composed of rutile SnO2 crystals arranged in a tetragonal pattern, with individual crystallites measuring approximately 100 nanometers in size. SEM images depicted the surface of SnO2 resembling a sponge with fine pores facilitating dye adsorption and electron mobility. Moreover, a decrease in average particle size was observed with increasing dye concentration, with the average grain size of SnO2 particles being below 100 nanometers at lower dye concentrations. TGA measurements indicated a phase transition occurring around 400 °C.

Photoluminescent Y2O3:Eu3+@PVA composite dispersions and films for anti-counterfeiting ink applications

The development of high-tech anti-counterfeiting inks to detect counterfeit products is a crucial task for almost every aspect of modern life around the world. Herein, we report the synthesis of photoluminescent xY2O3:Eu3+@PVA (x = 0, 1, 2.5, 5, 10, 15, and 20 wt%) composite dispersions and films and demonstrate their potential for anti-counterfeiting inks applications. Laser-synthesized m-Y2O3:Eu3+ nanoparticles (daver = 20.3 ± 6.9 nm) with strong red luminescence due to 5D0 → 7F0-4 transitions of Eu3+ were used as a pigment to create luminescent composites. Detailed photoluminescence properties of the obtained composite dispersions and films as a function of m-Y2O3:Eu3+ content were investigated in combination with SEM, EDX, UV–Vis and IR spectroscopy data. Tuning of the CIE coordinates of xY2O3:Eu3+@PVA is observed by changing the excitation wavelength. The results of SEM showed that the photoluminescent nanoparticles were uniformly distributed in the PVA film. Photoluminescent m-Y2O3:Eu3+-doped PVA composite inks can be applied via spray, brush, and screen-printing techniques to create security features on various surfaces, including glass, ceramics, paper, plastics, and currency notes. These inks remain stable for at least four months and offer a distinctive luminescent signature that is challenging to replicate, owing to the unique photoluminescence spectrum of Eu3+ in the monoclinic Y2O3 polymorph.

Exploring the efficiency enhancement of perovskite solar cells by chemical bath depositing SnO2 on mesoporous TiO2 electrode

This study presents a groundbreaking approach to enhance the efficiency of perovskite solar cells (PSCs) by employing Chemical Bath Deposited (CBD) SnO2 on mesoporous TiO2 (m-TiO2) as an electron transport layer (ETL) without a traditional compact TiO2 (c-TiO2) layer between FTO (fluorine-doped tin oxide) and m-TiO2 ETL. Our investigation reveals that this method significantly improves carrier dynamics, as evidenced by reduced time constants compared to traditional ETLs. The CBD SnO2 not only augments electron transport but also effectively reduces defect density in m-TiO2 films. These enhancements are reflected in the improved photovoltaic parameters of the cells, including higher open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and an impressive power conversion efficiency (PCE) exceeding 23.62 %. The study further underscores the scalability of this technology, highlighting advancements in screen printing and chemical bath deposition techniques vital for large-area PSC applications. Remarkably, the uniformity of PCE across large-area cells confirms the efficacy and consistency of this approach, which provides a new and general strategy for preparing high-efficiency PSCs.

Innovative designs for semitransparent carbon-based perovskite solar cells for building-integrated applications

Recently, semitransparent perovskite solar cells (SM-PSKs) have been developed, allowing part of the light to pass through the cell while absorbing the rest. Various strategies, including thinning the perovskite layer, innovative electrode materials, and incorporating plasmonic nanoparticles, have been explored, leading to efficiencies up to 14.78 % and transparency of 26.7 %. However, such cells face stability issues and are mostly fabricated in a controlled environment, limiting their scalability to module level and reducing their commercialization prospects. In contrast, carbon incorporation has shown potential for extending the lifespan of opaque PSKs, exhibiting remarkable stability of 1000 h and efficiencies exceeding 16 %. This study employs carbon-based perovskite solar cells fabricated using the screen printing technique with environmental conditions maintained at ambient levels for both temperature and humidity. The architecture of the cell is carefully modified to obtain several novel designs of semitransparent carbon-based perovskite solar cells (CSM-PSKs). UV–Vis spectroscopy tests are performed for each CSM-PSK, resulting in different average visible transparencies (AVT). The electrical properties of the opaque and proposed CSM-PSK designs are characterized using a Solar Simulator (Model: Solixon A-70-CU-2). Among the designs, one CSM-PSK demonstrates superior performance with an AVT of 8.65 % and a power conversion efficiency (PCE) of 5.6 %, highlighting their scalability for sustainable building-integrated energy solutions.

Investigation the Influence of Calcination Temperature on Structural, Electrical and Gas Sensing Properties MnO&lt;sub&gt;2&lt;/sub&gt; Thick Films

Metal oxide nanoparticles are widely used in various fields, including catalysis, sensing, energy storage, and more. Manganese dioxide (MnO2) is a promising material for gas sensors due to its sensitivity to various gases, including oxidizing and reducing gases. The calcination temperature affects their size, crystallinity, surface area, and other properties. In the present research work, the influence of calcination temperature on the structural, electrical and gas sensing properties of MnO2 nanoparticles or nanopowders was investigated. The MnO2 nanopowder was calcinated at 200, 400, 600, and 800 °C in a muffle furnace for 4 hours. After that, using the calcinated powder of MnO2, the thick films were prepared using the standard screen printing technique. The structural characterizations were investigated using SEM, EDS, and XRD. It has been found that as the calcination temperature is increased, the electrical, structural, and gas-sensing properties of MnO2 change. The prepared thick films calcinated at 200, 400, 600, and 800 °C are labeled as samples 1, 2, 3, and 4, respectively, in this paper. It has been found that sample 4 shows maximum resistivity, a more specific surface area, a smaller crystallite, and a maximum gas response to H2S gas. The maximum sensitivity was found to be 76.32% to H2S gas at operating temperature 120 °C. The response and recovery time was also found quickly.

An adaptive-conforming biodegradable flexible power supply based on continuous glucose oxidation

This paper reports an adaptive degradable flexible power supply. The power supply is produced using a batch-printed, easy-to-operate screen-printing technique that converts the chemical energy of glucose and oxygen into electricity. The power supply has stable current and voltage outputs in vitro, delivering a consistent open circuit potential of 0.2 V in vitro. Due to the flexibility and degradability of the power supply, the power supply can be implanted anywhere in the tissue. This breaks through the limitation of location, for example, mechanical energy harvesters can only be implanted in places with frequent movements. And due to the degradable nature of the power supply, surgical resection is avoided. Glucose and oxygen are ubiquitous and abundant in interstitial fluid. The in vivo experimental results prove that the power supply can power the light-emitting diode and have a stable current output. Therefore, the power supply is expected to provide internal power for implantable devices, avoiding transmission from external sources such as radio frequency.

Graphene-enhanced manganese dioxide functional ink infused with polyaniline for high-performance screen-printed micro supercapacitor

In the world of miniature advancements in technology, a current champion has emerged: the micro supercapacitors. In order to fabricate these micro-supercapacitors, we have developed a promising and user-friendly approach for printing a conductive functional ink containing a ternary composite of manganese dioxide (MnO2) nanoparticles, Graphene, and polyaniline (PANI) as a dopant. Screen-printing technique was employed to fabricate micro-supercapacitors using the nanocomposite conductive ink. The performance of the energy storage device was examined using flexible symmetric and asymmetric, with an aqueous 1 M KOH electrolyte. According to this strategy, the characterisation and electrochemical study results revealed that doping PANI into both symmetric and asymmetric devices significantly increased the material’s capacitive performance of areal capacitance 167 mFcm−2 for MnO2/Graphene/PANI-5 composite (MGP-5) and 292.5 mFcm−2 for asymmetric supercapacitor (ASSC) at 5 mVs−1. Furthermore, the asymmetric supercapacitor displayed outstanding cyclic stability, retaining 93.6% of its capacitance after 10000 cycles. This underscores the possibility of incorporating polyaniline (PANI) into MnO2 and graphene matrices as efficient blueprints for the development of superior electrode materials. The improvement represents a significant step forward, opening avenues for the future development of novel devices and their integration into top-of-the-line flexible energy storage systems.

Lanthanide conjugated colour-tunable luminescent hydrogels as direct printable inks for anticounterfeiting and forensic applications

Counterfeiting is a global concern that jeopardizes individuals, businesses, and nations, costing trillions of USD annually. To combat this, researchers are continuously developing strong security features to formulate anti-counterfeiting inks. Herein, a novel approach has been adopted to prepare advanced luminescent hydrogel with ligand H3BTC for important applications in authentication of goods and fingerprint detection. In present investigations, Tb3+ and Eu3+ ions conjugated H3BTC hydrogels have been synthesized which emits strong green (542 nm) and red (614 nm) colours under UV lamp (254 nm). Additionally, the colour tunability for intermediate colours i.e. yellow and orange have also been achieved by varying the concentrations of Eu and Tb in H3BTC hydrogel. These hydrogels can be directly printed on any substrate using conventional screen-printing techniques. Moreover, these hydrogels can directly be used for thumb impressions with green and red emissions under 254 nm UV lamp, while appearing white in normal light and making them promising for new alternative solutions to design next-generation security ink for anticounterfeiting and forensic applications.

Investigating the electrical and thermal properties of Cu and Al-doped ZnO thick films using the screen-printing technique for thermal resistance applications

The important properties of prepared Zinc Oxide (ZnO) thick films were investigated. The electrical and thermal properties of ZnO thick films were measured and analyzed using the MATLAB simulation tool. On a glass substrate, thick films of pure ZnO as well as ZnO doped with Cu and Al materials were fabricated using the screen-printing technique. The electrical parameters were calculated using the half-bridge approach to determine the unknown resistance, change in current, and voltage. The half-bridge circuit having a 50 M Ω reference resistance with 30 V excitation voltage. The thermocouple transducer (K type) was used to measure the heating and cooling temperature between 40 °C to 370 °C. The measured maximum TCR values are 0.0095 ppm/°C for pure ZnO film, 0.0068 ppm/°C for Cu-doped ZnO film, and 0.0123 ppm/°C for Al-doped ZnO film. The maximum measured resistance values are 5.9 × 107 Ω for pure ZnO film, 5.9 × 107 Ω for Cu-doped ZnO film, and 5.9 × 107 Ω for Al-doped ZnO film. Using MATLAB simulation, it was possible to observe key factors including the activation energy, unknown resistance, IV characteristics, thermal properties, temperature coefficient resistance (TCR) and resistive linear behavior of the ZnO films.