Search Results (99)

The purpose of this work is to demonstrate that laser-induced conductive tracts in AlN ceramic can be applied for fabrication of an integrated resistive heating element. Nanosecond laser processing at a wavelength of 1064 nm of ceramic in vacuum is used for a formation of conductive areas. It is demonstrated that the applied laser fluence and the number of pulses influence strongly the electrical properties of the material in the irradiated zone. The resistance value of the produced tracks with a length of about 4 mm and width of about 1 mm may vary from 17 to about 2000 Ohms, depending on the processing conditions. The material in the processed zone is characterized by means of surface composition, morphology, and electric properties. It is found that the electrical conductivity of the formed structure is based on the ceramic decomposition and formation of aluminum layer. The analysis of the influence of the temperature on the electrical resistance value shows that the material’s conductivity could be preserved after annealing, as in the present study it is confirmed up to 300 °C. The ability of the formed tracks to serve as a basis element of ceramic integrated resistive heater is studied by applying DC voltage. It is found that the fabricated element can be used with a high reliability to about 90 °C without special requirements for contact design and encapsulation. Operation at higher temperatures is also demonstrated as the maximal one achieved is about 150 °C at 10V. The performance of the heater is investigated and discussed as the operation range is defined. The proposed element can be a basis for a design of an integrated heater in ceramic with high stability and applications in everyday life and research. Full article

Based on a distributed feedback laser diode (DFB-LD) under optical feedback, a novel scheme for generating neuron-like tonic spiking is proposed, and the characteristics of the generated neuron-like tonic spiking are numerically investigated. Firstly, through adopting the Lang–Kobayashi model to analyze the nonlinear dynamics of the DFB-LD under optical feedback, the switching between different dynamic states is observed by continuously increasing the biased current of the DFB-LD, and the current regions required for driving the DFB-LD into the stable states and period one (P1) states are determined. Next, a rectangular electrical pulse is introduced as a stimulus signal to modulate the DFB-LD, and the lower and upper current values of the rectangular electrical pulse are set at the regions in which the DFB-LD operates at the stable state and P1 state, respectively. Under suitable operation parameters, sub-nanosecond tonic spiking can be generated. Finally, through adjusting the delayed time of optical feedback and selecting the matched rectangular electrical pulse, the frequency of tonic spiking can be detuned within a range exceeding 5 GHz. Full article

Upscaling perovskite solar cells and modules requires precise laser patterning for series interconnection and spatial characterization of cell parameters to understand laser–material interactions and their impact on performance. This study investigates the use of nanosecond (ns) and picosecond (ps) laser pulses at varying fluences for the P3 patterning step of perovskite solar cells. Hyperspectral photoluminescence (PL) imaging was employed to map key parameters such as optical bandgap energy, Urbach energy, and shunt resistance. The mappings were correlated with electrical measurements, revealing that both ns and ps lasers can be utilized for effective series interconnections with minimal performance losses at optimized fluences. Our findings provide a deeper understanding of fluence-dependent effects in P3 patterning. Moreover, the results demonstrate that the process window is robust, allowing for reasonable cell performance even with deviations from optimal parameters. This robustness, coupled with the scalability of the laser patterning process, emphasize its suitability for industrial module production. Full article

Cancer treatment has historically depended on conventional methods like chemotherapy, radiation, and surgery; however, these strategies frequently present considerable limitations, including toxicity, resistance, and negative impacts on healthy tissues. In addressing these challenges, drug-free cancer therapies have developed as viable alternatives, utilizing advanced physical and biological methods to specifically target tumor cells while reducing damage to normal tissues. This review examines several drug-free cancer treatment strategies, such as high-intensity focused energy beams, nanosecond pulsed electric fields, and photothermal therapy as well as the use of inorganic nanoparticles to promote selective apoptosis. We also investigate the significance of targeting the tumor microenvironment, precision medicine, and immunotherapy in the progression of personalized cancer therapies. Although these approaches demonstrate significant promise, challenges including scalability, safety, and regulatory obstacles must be resolved for clinical application. This paper presents an overview of current research in drug-free cancer therapies, emphasizing recent advancements, underlying scientific principles, and the steps required for clinical implementation. Full article

Polypropylene (PP) membranes have found diverse applications, such as in wastewater treatment, lithium-ion batteries, and pharmaceuticals, due to their low cost, excellent mechanical properties, thermal stability, and chemical resistance. However, the intrinsic hydrophobicity of PP materials leads to membrane fouling and filtration flux reduction, which greatly hinders the applications of PP membranes. Dielectric barrier discharge (DBD) is an effective technique for surface modification of materials because it generates a large area of low-temperature plasma at atmospheric pressure. In this study, O₂ was added to nanosecond pulsed Ar DBD to increase its reactivity. Electrical and optical diagnostic techniques were used to study the discharge characteristics of the DBD at varying O₂ contents. The uniformity of the discharge was quantitatively analyzed using the observed discharge images. Water contact angle measurements were used to assess the surface hydrophilicity of polypropylene. The surface morphology and chemical composition of the PP materials before and after treatment were analyzed using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that the moderate addition of O₂ enhances surface hydrophilicity and the uniformity of the modification. By increasing the O₂ addition from 0% to 0.1%, the average power increased from 4.19 W to 5.79 W, and the energy efficiency increased from 17.78% to 21.51%. The water contact angle of the DBD-treated PP showed a tendency to decrease and then increase with increasing O₂ content, with the optimum O₂ addition determined to be 0.1%. Under this condition, the water contact angle of the PP surface decreased by 31.88°, which is 52.31% lower than the untreated surface. O₂ increases the number of oxygen-containing polar groups (-OH, C=O, and O-C=O) on the surface of the material, and deepens and densifies the grooves on the surface of the PP material, resulting in an increase in the hydrophilicity of the PP surface. Full article

Electroporation ablation, as an innovative cancer treatment, not only preserves the structure and function of affected organs but also significantly reduces surgical risks, offers patients a safer and more effective therapeutic option, and demonstrates immense potential in the field of oncology. This paper presents the innovative design of a high-voltage nanosecond pulse generator triggered by a silicon carbide (SiC) photoconductive switch. The generator is capable of stably outputting adjustable voltages ranging from 10 kV to 15 kV, with pulse widths precisely controlled between 10 and 15 nanoseconds, and an operating frequency adjustable from 1 Hz to 10 Hz. This device enables instant activation and deactivation of the pulse generator during ablation, enhancing the efficiency of strong electric field applications and preventing overtreatment due to delayed shutdown. This paper introduces the structure and basic principles of this novel SiC photoconductive switch-triggered pulse device and reports on the impact of device-related pulse parameters on the ablation effect of hepatocellular carcinoma cells through cell experiments. Under optimal ablation parameters, the CCK8 results show that the number of viable cells is only 0.7% of that in the untreated control group after 12 h of subculture following ablation. These findings hold significant importance for expanding the application areas of SiC devices. Full article

In this work, atmospheric pulsed laser deposition was used to prepare photosensitive elements. This technology is a practical and relatively inexpensive way of obtaining highly porous nanostructures composed of nanoparticles or nanoaggregates characterized by a large surface-to-volume ratio. Samples were produced via laser nanosecond or picosecond laser ablation of pure ZnO or mixed ZnO-TiO₂ targets on quartz substrates with pre-deposited gold electrodes. The structure, morphology, optical, and electrical properties of the nanostructures obtained were studied regarding the sample composition and laser ablation regime applied. The ablation of a mixed ZnO-TiO₂ target led to the fabrication of composite samples consisting of ZnO and Zn₂TiO₄ nanoparticles. The electrical properties of pure and composite samples were studied under exposure to UV light irradiation. It was found that the photosensitive properties of the samples depended on the ablation regime applied. The dark current measured for the nanosecond-deposited samples was a few nA, which was an order of magnitude larger compared to the picosecond-deposited samples. The value of the photogenerated current of the nanosecond-deposited samples was 10³-times higher than that of the picosecond-deposited samples. This is due to the lower absorption of the picosecond-deposited samples, as well as to the presence of defect-related radiative recombination in the picosecond-deposited samples, which limits the photocurrent rise. The estimated rise and decay times were longer for the composite samples independently of the deposition regime applied. Full article

Thin films based on tungsten oxide (WO₃) were grown by nanosecond pulsed laser deposition on alumina printed-circuit boards to fabricate electrochemical sensors for nitrogen dioxide (NO₂) detection. Samples exposed to thermal annealing (400 °C for 3 h) were also produced to compare the main properties and the sensor performance. Before gas testing, the morphology and structural properties were investigated. Scanning electron microscopy and atomic force microscopy showed the formation of granular films with a more compact structure before the thermal treatment. Features of the main WO₃ phases were identified for both as-deposited and annealed samples by Raman spectroscopy, whereas X-ray diffraction evidenced the amorphous nature of the as-deposited samples and the formation of crystalline phases after thermal annealing. The as-deposited samples showed a higher W/O ratio, as displayed by energy-dispersive X-ray spectroscopy. An Arrhenius plot revealed a lower activation energy (0.11 eV) for the as-deposited thin films, which are the most electrically conductive samples, presenting a better gas response (30% higher than the response of the annealed ones) in the investigated NO₂ concentration range of 5–20 ppm at the moderate device operating temperature of 75 °C. This behavior is explained by a larger quantity of oxygen vacancies, which enhances the sensing mechanism. Full article

Currently, tissue engineering technologies are promising for the restoration of damaged organs and tissues. For regeneration of electrically conductive tissues or neural interfaces, it is necessary to provide electrical conductivity for the transmission of electrophysiological signals. The developed biocomposite structures presented in this article possess such properties. Their composition includes bovine serum albumin (BSA), gelatin, eosin-Y and single-walled carbon nanotubes (SWCNTs). For the first time, a biocomposite structure was formed from the proposed hydrogel using a nanosecond laser, and a two-photon absorption cross section value of 580 GM was achieved. Increased viscosity over 3 mPa∙s and self-focusing with a nonlinear refractive index of 42 × 10⁻¹² cm²/W make it possible to create a biocomposite structure over the entire specified area. The obtained electrical conductivity value was 19 mS∙cm⁻¹, due to the formation of effective electrically conductive networks. For a biocomposite with a concentration of gelatin 3 wt. %, formed by low-energy near-IR pulses, the survival of Neuro 2A nerve tissue cells was confirmed. The obtained results are important for the creation of new tissue engineering structures and neural interfaces from a biopolymer hydrogel based on the organic dye eosin-Y and carbon nanotubes by two-photon polymerization. Full article

Background/Objectives: Electrochemotherapy (ECT) is a safe and efficient method of targeted drug delivery using pulsed electric fields (PEF), one that is based on the phenomenon of electroporation. However, the problems of electric field homogeneity within a tumor can cause a diminishing of the treatment efficacy, resulting only in partial response to the procedure. This work used gold nano-particles for electric field amplification, introducing the capability to improve available elec-trochemotherapy methods and solve problems associated with field non-homogeneity. Methods: We characterized the potential use of gold nanoparticles of 13 nm diameter (AuNPs: 13 nm) in combination with microsecond (0.6–1.5 kV/cm × 100 μs × 8 (1 Hz)) and nanosecond (6 kV/cm × 300–700 ns × 100 (1, 10, 100 kHz and 1 MHz)) electric field pulses. Finally, we tested the most prominent protocols (microsecond and nanosecond) in the context of bleomycin-based electrochemotherapy (4T1 mammary cancer cell line). Results: In the nano-pulse range, the synergistic effects (improved permeabilization and electrotransfer) were profound, with increased pulse burst frequency. Addi-tionally, AuNPs not only reduced the permeabilization thresholds but also affected pore resealing. It was shown that a saturated cytotoxic response with AuNPs can be triggered at significantly lower electric fields and that the AuNPs themselves are non-toxic for the cells either separately or in combination with bleomycin. Conclusions: The used electric fields are considered sub-threshold and/or not applicable for electrochemotherapy, however, when combined with AuNPs results in successful ECT, indicating the methodology’s prospective applicability as an anticancer treatment method. Full article

In this study, a single-outer-spiral electrode with inductance of 20 μH is employed to couple the energy input of a bipolar nanosecond pulse for the purpose of generating a large-scale atmospheric pressure plasma jet. When the spiral electrode is wrapped around a plasma jet tube with a length of 35 cm, the electrical field can be optimized, resulting in a stable laminar flow field, and a plasma jet with a length and diameter larger than 14 cm and 1.2 cm can be generated. A comparative study of the bipolar and unipolar pulse excitation voltages is also conducted, showing that the maximum lengths of the plasma jet excited by a bipolar pulse voltage, positive pulse voltage, and negative are 14 cm, 10 cm, and 7 cm, respectively. The temporal and spatially resolved spectra of the plasma jets excited by both bipolar and unipolar pulses are investigated, respectively, and the main physiochemical processes of the active species and the plasma dynamics’ evolution are discussed. Full article

Plasma focus devices represent a class of hot and dense plasma sources that serve a dual role in fundamental plasma research and practical applications. These devices allow the observation of various phenomena, including the z-pinch effect, nuclear fusion reactions, plasma filaments, bursts, shocks, jets, X-rays, neutron pulses, ions, and electron beams. In recent years, considerable efforts have been directed toward miniaturizing plasma focus devices, driven by the pursuit of both basic studies and technological advancements. In this paper, we present the design and construction of a compact, portable pulsed plasma source based on plasma focus technology, operating at the ~2–4 Joule energy range for versatile applications (PF-2J: 120 nF capacitance, 6–9 kV charging voltage, 40 nH inductance, 2.16–4.86 J stored energy, and 10–15 kA maximum current at short circuit). The components of the device, including capacitors, spark gaps, discharge chambers, and power supplies, are transportable within hand luggage. The electrical characteristics of the discharge were thoroughly characterized using voltage and current derivative monitoring techniques. A peak current of 15 kiloamperes was achieved within 110 nanoseconds in a short-circuit configuration at a 9 kV charging voltage. Plasma dynamics were captured through optical refractive diagnostics employing a pulsed Nd-YAG laser with a 170-picosecond pulse duration. Clear evidence of the z-pinch effect was observed during discharges in a deuterium atmosphere at 4 millibars and 6 kilovolts. The measured pinch length and radius were approximately 0.8 mm and less than 100 μm, respectively. Additionally, we explore the potential applications of this compact pulsed plasma source. These include its use as a plasma shock irradiation device for analyzing materials intended for the first wall of nuclear fusion reactors, its capability in material film deposition, and its utility as an educational tool in experimental plasma physics. We also show its potential as a pulsed plasma thruster for nanosatellites, showcasing the advantages of miniaturized plasma focus technology. Full article

The phenomenon known as bipolar cancellation is observed when biphasic nanosecond electric field pulses are used, which results in reduced electroporation efficiency when compared to unipolar pulses of the same parameters. Basically, the negative phase of the bipolar pulse diminishes the effect of the positive phase. Our study aimed to investigate how bipolar cancellation affects Ca²⁺ electrochemotherapy and cellular response under varying electric field intensities and pulse durations (3–7 kV/cm, 100, 300, and 500 ns bipolar 1 MHz repetition frequency pulse bursts, n = 100). As a reference, standard microsecond range parametric protocols were used (100 µs × 8 pulses). We have shown that the cancellation effect is extremely strong when the pulses are closely spaced (1 MHz frequency), which results in a lack of cell membrane permeabilization and consequent failure of electrochemotherapy in vitro. To validate the observations, we have performed a pilot in vivo study where we compared the efficacy of monophasic (5 kV/cm × ↑500 ns × 100) and biphasic sequences (5 kV/cm × ↑500 ns + ↓500 ns × 100) delivered at 1 MHz frequency in the context of Ca²⁺ electrochemotherapy (B16-F10 cell line, C57BL/6 mice, n = 24). Mice treated with bipolar pulses did not exhibit prolonged survival when compared to the untreated control (tumor-bearing mice); therefore, the bipolar cancellation phenomenon was also occurrent in vivo, significantly impairing electrochemotherapy. At the same time, the efficacy of monophasic nanosecond pulses was comparable to 1.4 kV/cm × 100 µs × 8 pulses sequence, resulting in tumor reduction following the treatment and prolonged survival of the animals. Full article

Pulsed power equipment is often characterized by high energy density and field intensity. In the presence of strong electric field intensity, charge accumulation within insulators exacerbates electric field non-uniformity, leading to potential insulation breakdown, thereby posing a significant threat to the safe operation of pulsed power equipment. In this manuscript, we introduce nonlinear composite materials with field-dependent conductivity and permittivity to adaptively regulate the distribution of the pulsed electric field in insulation equipment. Finite-element modeling and analysis of the needle-plate electrodes and high-voltage bushing are carried out to comprehensively investigate the non-uniformity of the distribution of the electric field and the homogenization effect of various nonlinear materials in the presence of pulsed excitations of different timescales. Numerical results indicate that the involvement of nonlinear composite materials significantly improves the electric field distribution under pulse excitations. In addition, variations in the rising time of the pulses affect the maximum electric field intensity within the insulators considerably, but for pulses of nanosecond and microsecond scales, the tendencies are the opposite. Finally, via the simulations of the bushing, we illustrate that some measures proposed for improving the uniformity of the electric field under low frequencies, e.g., increasing the length of the electric field equalization layer and the distance of the underside of the electric field equalization layer from the grounding screen, are still effective for the homogenization of pulsed electric field. Full article

Electroporation-based procedures employing nanosecond bipolar pulses are commonly linked to an undesirable phenomenon known as the cancelation effect. The cancellation effect arises when the second pulse partially or completely neutralizes the effects of the first pulse, simultaneously diminishing cells’ plasma membrane permeabilization and the overall efficiency of the procedure. Introducing a temporal gap between the positive and negative phases of the bipolar pulses during electroporation procedures may help to overcome the cancellation phenomenon; however, the exact thresholds are not yet known. Therefore, in this work, we have tested the influence of different interphase delay values (from 0 ms to 95 ms) using symmetric bipolar nanoseconds (300 and 500 ns) on cell permeabilization using 10 Hz, 100 Hz, and 1 kHz protocols. As a model mouse hepatoma, the MH-22a cell line was employed. Additionally, we conducted in vitro electrochemotherapy with cisplatin, employing reduced interphase delay values (0 ms and 0.1 ms) at 10 Hz. Cell plasma membrane permeabilization and viability dependence on a variety of bipolar pulsed electric field protocols were characterized. It was shown that it is possible to minimize bipolar cancellation, enabling treatment efficiency comparable to monophasic pulses with identical parameters. At the same time, it was highlighted that bipolar cancellation has a significant influence on permeabilization, while the effects on the outcome of electrochemotherapy are minimal. Full article