Laser-induced Copper Research Articles

Laser-induced copper superhydrophobicity to improve heat transfer and reduce limestone deposition in water heating systems

Laser-induced copper superhydrophobicity to improve heat transfer and reduce limestone deposition in water heating systems

Laser surface processing technology for performance enhancement of TENG

<p>The triboelectric nanogenerator (TENG), as a new energy harvesting device, can efficiently harvest mechanical energy from the environment to provide continuous power for electronic devices, which has great potential for powering intelligent distributed network. Laser processing technology, which enables structural, phase, and property control at different scales, can quickly and easily complete the surface patterning of TENG and facilitate efficient energy harvesting. In this work, we outline the working modes and principles of TENG, review the research progress of laser surface processing technology for fabricating TENG in recent years, including laser-induced graphene (LIG), laser ablation, laser carbonization, laser-induced copper, etc., and perspectives on the challenges and future directions for development of laser surface processing for performance enhancement of TENG.</p>

Lagrangian perspective on the expansion dynamics and shielding effect of femtosecond laser-induced copper plasma plumes

Femtosecond laser ablation of metals generates a strongly ionized plasma plume near the irradiated surface. The resulting plasma shielding effect can reduce subsequent laser energy deposition and lower nanomachining efficiency, especially during multi-pulse irradiation. Understanding the spatiotemporal evolution of the laser-induced plasma and its associated shielding effect is, therefore, crucial. A hybrid two-temperature and direct simulation Monte Carlo (TTM-DSMC) computational model is developed in this study, which synergistically couples the ultrafast laser–metal interaction physics and the plasma collisional transport. The model simulates the plasma properties including electron density, temperature dynamics, reflectivity, and energy attenuation throughout the plume expansion process from femtosecond to nanosecond timescales. A complex “penguin-shaped” plasma plume with internal shockwaves is observed due to the effects of double-pulse irradiation. Significantly enhanced plasma reflectivity and reduced laser energy deposition demonstrate the accumulated shielding effect, which increases with higher plasma density accumulation when the pulse separation is insufficient. Our model provides valuable theoretical guidance for optimizing processing parameters to enhance efficiency and precision in femtosecond laser machining. The integrated TTM-DSMC approach could also facilitate the study of laser-induced plasmas in other contexts like material characterization and nanoparticle synthesis.

Low-cost, wearable, multifunctional antennas based on laser-induced copper for wireless information and power transmission

Low-cost, wearable, multifunctional antennas based on laser-induced copper for wireless information and power transmission

Laser-induced fibers and copper phthalocyanine modified laser-induced graphene electrodes for sensitive and selective electrochemical detection of nitrite.

We have recently reported laser-induced fibers (LIF) as a promising nanomaterial that possesses good electrochemical activity and are easily manufacturable. In this paper, for the first time, the application of LIF as functionalization materials on laser-induced graphene (LIG) electrodes for the detection of nitrate is demonstrated. The as-fabricated LIF surfaces on Kapton were extracted by ultrasonication as a dispersion and were used to modify the surface of the LIG electrode. An enhancement in active surface area from 0.669 cm2 for bare LIG to 0.83 cm2 for LIF-modified LIG was observed. Similarly, the heterogeneous electron transfer rate increased from 0.190 to 0.346 cm s-1 for LIF/LIG electrodes. The electrochemical detection of nitrite was achieved by modifying the LIG with a nanocomposite of LIF and copper phthalocyanine (CuPc). The presence of CuPc provided the desired catalytic activity towards the oxidation of nitrite, and the LIF enhanced the electron transfer to the electrode. Such a synergetic combination of the LIF embedded with CuPc enabled reaching a low limit of detection (LoD) of 0.12 μM, a large linear range from 10 to 10 000 μM and good selectivity in the presence of potential interferants. The sensor had a long shelf life of 30 days and good analytical capability to detect nitrite in mineral, tap, and groundwater. The potential of LIF is largely unexplored and the findings reported here on the fibers would open manifold opportunities for realizing novel applications.

Investigation of the signal uncertainty in laser-induced breakdown spectroscopy based on error propagation considering self-absorption

The relatively high signal uncertainty of laser-induced breakdown spectroscopy (LIBS) is a key obstacle to its analytical performance and large-scale application. Despite the extensive research efforts to reduce signal uncertainty, few fundamental studies have been conducted because of the complexity of the microscopic mechanisms involved in plasma evolution. Recently, error propagation analysis has provided an inspiring perspective by linking signal uncertainty with plasma property fluctuations, while further investigation is urgently needed due to the limitations of the employed plasma diagnostic techniques. In this study, a spectrum fitting model was proposed for optically thick and homogeneous plasmas to provide more reliable plasma properties for error propagation analysis for the first time. The model was applied to laser-induced copper plasmas using a laser wavelength of 1064 nm and a pulse duration of 25 ns. The uncertainty of an atomic copper line was analyzed at different delay times. Our findings revealed that the fluctuation of columnar total number density was the most significant factor under the investigated conditions, and that the correlation term of temperature and columnar total number density made a considerable negative contribution. Furthermore, self-absorption suppressed the magnitudes of major contribution terms for the signal uncertainty of LIBS.

Theoretical estimations of the incoherent pumping of laser-induced copper plasma

The optical pumping of laser-induced copper plasma by incoherent light of a fast-discharge xenon flashlamp is proposed to enhance the stimulated emission of the laser-induced plasma (LIP). To study the spatiotemporal evolution of the incoherent pumping of LIP, a numerical approach based on the collisional-radiative model and kinetic equations has been employed. The influence of total density and gas temperature on the stimulated emission and gain coefficient of the plasma plume was studied. The results show an enhancement of the intensity of the spectral lines of atomic copper. This idea demonstrates that the pumping of LIP by a low energy, fast-discharge flashlamp may be replacement for the expensive laser-pumped LIP for the improvement of the sensitivity of the related spectral diagnostics methods of plasma, such as laser-induced breakdown spectroscopy.

Formation of subsurface Cu-O-Si system through laser-induced plasma-assisted copper penetration for fabricating robust adhesive copper wire on glass substrate

This study reports an approach, laser-induced plasma-assisted penetration (LIPAP), to facilitate copper diffusion to the glass interior using a femtosecond laser. TEM images and EDS analysis showed copper particles could diffuse into the glass up to 300 nm from the surface. The diffusion was driven by the local high temperatures generated by consecutively incident highly repetitive laser pulses. Furthermore, the HR-TEM images showed that, between the surface copper layer and the internal amorphous SiO2, there were crystalline regions of copper nanoparticles and copper oxides and an amorphous zone, belonging to the Cu-O-Si system, through which, the surface copper layer was firmly connected with the glass substrate. The LIPAPed copper layer then served as a patterning seed for electroless-plating of highly conductive copper wires. Consequently, copper wires with a resistivity of 9.9×10-8Ωm were obtained. Finally, a scratch adhesion test was performed to quantify the adhesion of the resulting copper films. Results showed that copper remained adhered to the surface before reaching the ultimate glass crush load of 30 N, corresponding to normal scratch stress of 240 MPa. Accordingly, based on the LIPAP-formed special subsurface nanostructures serving as the mechanical anchoring basis, highly conductive and adhesive electroless-plated copper wires were achieved.

Comparative study on the copper plasma confined with upward and downward conical cavities in laser-induced breakdown spectroscopy

In this study, the confinement effects of upward and downward conical cavities on laser-induced copper plasma were investigated by optical emission spectroscopy and fast imaging technique. It follows from the time-integrated spectra, the time-resolved spectra, and the spatial distributions of spectral intensity that the superior enhancement effects on spectral intensity are obtained in the upward conical cavity. Compared to the plasmas without confinement, plasma temperature and electron number density are increased in the presence of upward conical cavity, while no enhancements are obtained in the downward conical cavity. Reflection model of shockwave in a conical cavity is established to interpret these phenomena. The enhancement of the plasma plume confined in the upward conical cavity results from the compression of the plume towards its central region by the shockwave, as well as the accelerated collisions between the particles therein. No enhancement effect of the plasma in the downward conical cavity is obtained because of the radial expansion of plasma plume and the population reduction of excited species in the plasma primary core due to the pressure of oblique downward shockwave. This shockwave reflection model is further verified by the fast imaging, where the direct observation of the plasma plume agrees well with the enhancement effects of the two cavities on the spectral intensity.

High-performance triboelectric nanogenerator powered flexible electroluminescence devices based on patterned laser-induced copper electrodes for visualized information interaction

Flexible electroluminescence (EL) devices with self-powered features are of significant interest in information interaction, wearable electronics, and artificial intelligence. However, one of the most challenging issues on realization of such devices is the development of a customizable metal electrode with a high-efficient, low-cost and facile manufacturing technique in comparison with traditional physical vapor deposition. Herein, high-performance triboelectric nanogenerator (TENG) powered flexible EL devices are reported based on customizable patterned laser-induced copper (LIC) electrodes through a high-efficient, facile, and mask-free laser direct writing (LDW) technology. The fabricated LIC electrode endows high conductivity of 0.4 Ω/sq, mechanical durability, and long-term stability for over 20 weeks. Meanwhile, the LIC-based TENG is fabricated to harvest mechanical energy and can achieve high output performances to power various portable electronics. Moreover, the flexible self-powered EL devices based on letters “TENG”-patterned LIC electrodes can be lighted up by the LIC-based TENG operated at even 0.3 Hz for customizable patterned display. Furthermore, the quick response (QR) code-patterned self-powered EL device is developed to achieve real-time visualized information interaction by reading out of smartphone. Consequently, this work demonstrates the tremendous potential for energy harvesting, customizable patterned self-powered EL display, information interaction and other field.

High-Performance Triboelectric Nanogenerator Powered Flexible Electroluminescence Devices Based on Patterned Laser-Induced Copper Electrodes for Visualized Information Interaction

High-Performance Triboelectric Nanogenerator Powered Flexible Electroluminescence Devices Based on Patterned Laser-Induced Copper Electrodes for Visualized Information Interaction

Investigation of Shielding Effects on Picosecond Laser-Induced Copper Plasma Characteristics under Different Focusing Distances

In traditional laser-induced breakdown spectroscopy (LIBS) applications, the line intensity and analysis capability are susceptible to plasma shielding. To investigate the shielding effects on the characteristics of Cu plasma in air, a ~120-picosecond laser with a wavelength of 1064 nm was employed to produce plasma. The plasma temperature and electron density were calculated under the condition of local thermal equilibrium (LTE) and optically thin, while the relationships between the line intensity, plasma temperature and electron density were analyzed. Moreover, the LTE condition was validated by the McWhirter relation, plasma relaxation time and diffusion length, and the optically thin condition was observed through the variation in line intensity. The results indicated that when the focal point was below the target surface, the plasma shielding was the weakest, and the highest line intensity could be obtained. In addition, there was a positive correlation between the increased plasma temperature and the degree of shielding effect. When the focal point was above the target surface, the high-irradiance pulse directly broke down the free air and produced a shock wave. Under the high pressure of the over-heated shock wave, the line intensity, plasma temperature and electron density increased again. This study provides an important insight into the experiments and applications of picosecond LIBS.

Polyaramid-Based Flexible Antibacterial Coatings Fabricated Using Laser-Induced Carbonization and Copper Electroplating.

A method for the fabrication of flexible electrical circuits on polyaramid substrates is presented based on laser-induced carbonization followed by copper electroplating. Locally carbonized flexible sheets of polyaramid (Nomex), by laser radiation, create rough and highly porous microstructures that show a higher degree of graphitization than thermally carbonized Nomex sheets. The found recipe for laser-induced carbonization creates conductivities of up to ∼45 S cm-1, thereby exceeding that observed for thermally pyrolyzed materials (∼38 S cm-1) and laser carbon derived from Kapton using the same laser wavelength (∼35 S cm-1). The electrical conductivity of the carbonized tracks was further improved by electroplating with copper. To demonstrate the electrical performance, fabricated circuits were tested and improvement of the sheet resistance was determined. Copper films exhibit antimicrobial activity and were used to fabricate customized flexible antibacterial coatings. The integration of laser carbonization and electroplating technologies in a polyaramid substrate points to the development of customized circuit designs for smart textiles operating in high-temperature environments.

Effect of sample temperature on spectroscopic investigation of laser-induced aluminum and copper plasma

In this work, the influence of samples temperature and laser energy on the optical emission spectra and plasma parameters of laser-induced breakdown spectroscopy for aluminum and copper metallic target is investigated. The samples are uniformly cooled down to −70 °C and heated up to 200 °C by an external liquid nitrogen and ceramic heater, respectively. The plasma formed is generated by ablating the surface targets using Nd:YAG laser with laser energies of 100 mJ, 200 mJ and 300 mJ. The emission spectra at ambient atmospheric pressure are recorded using HR4000 spectrometer. From these spectra, plasma temperatures and electron densities are determined by using Boltzmann plot and Stark broadening methods, respectively. A significant increase in the peak intensity of spectral lines is observed with increase in the laser energy as well as sample temperature for both elements. Both of these parameters have shown a clear influence on dynamics of laser-induced plasma for each species. In brief, both laser energy and sample temperature affect the emission intensity, temperature and density of the laser-induced plasma generated from aluminum and copper samples.

Dependence of radiation decay constant of laser produced copper plasma on focal position

Laser-induced copper plasma is investigated experimentally and theoretically. Laser-induced plasma on the surface of the copper sample is generated by focusing a nanosecond (∼7 ns) laser pulse. The experiment is performed in the ambient atmosphere at three different focal positions (lens to sample distances). The main objective of this work is to investigate the effect of the focal position on the radiation decay constant of the plasma. Experimental data are used for estimating the plasma temperature, electron density, ablated mass, and radiation decay constant. It is shown that these parameters essentially depend on the focal position with respect to the sample surface. The theory of relaxation of radiation is considered for the kinetic evolution of the plasma. The results of the theory are compared with the obtained experimental data.

Effect of distance between the laser spot and the cavity center on spatially confined laser-induced copper plasma

We investigated the effect of distance between the laser spot and the cavity center on spatially confined laser-induced copper plasma in air. Spatial cylindrical cavities with various diameters (2mm, 3mm, 4mm and 5mm) and heights (2mm, 4mm, 6mm and 8mm) were used to confine the plasma, and different enhancements were observed when the laser spot at different locations in the same cavity. The maximum enhancement factor for the spectral intensity of Cu atomic line to be around 9 was measured at a time delay of 2.5μs when the distance was 0mm. The plasma temperature was calculated by the Boltzmann plot method, including five Cu atomic lines (324.75nm, 327.40nm, 510.55nm, 515.32nm and 521.82nm). The enhancement of the plasma temperature had a similar trend with the spectral intensity and also showed a strong dependence on the distance. The results demonstrated that the enhancement effect at the center of the cavity was the most significant for the uniform and balanced compression of the reflected shock waves in all directions.

Detecting Temporal Changes of Self-Absorption in a Laser-Induced Copper Plasma from Time-Resolved Photomultiplier Signal Emission Profiles.

This work reports an investigation on the feasibility of using a photomultiplier tube (PMT) to follow the time evolution of self-absorption of copper resonance transitions at 324.7 nm and 327.4 nm. The plasma was obtained by focusing a Nd:YAG laser, operated at 1064 nm, on a series of aluminum alloy standard disks containing different copper concentrations. The results described have been obtained at different times and with different set-ups. These set-ups consisted of a Paschen-Runge polychromator, a LIBS 2000 spectrometer, and a spectrometer equipped with both an intensified charge-coupled device (ICCD) and PMT. Both PMT signals and time-resolved spectra were obtained and the ratio of the two Cu resonant lines was calculated, compared, and discussed. By selecting different delay times and integration gates of the PMT signals, the self-absorption effect of the Cu resonant lines was found to be changing, implying that, by careful selection of the integration window of PMT signals, the self-absorption may be minimized, thus improving the calibration linearity of the technique.

Laser induced selective electroless copper plating on polyurethane using EDTA-Cu as active material

Using EDTA-Cu as the active material and polyurethane as the matrix, flexible cathodes were fabricated by laser-induced electroless copper plating process (LPKF-LDS) and characterized by SEM, X-ray energy spectrum and Auger electron spectroscopy. Flexible cathodes prepared from EDTA-Cu and polyurethane showed good selectivity in copper plating process. Composition and particle morphology of EDTA-Cu, laser power, scanning speed, laser wavelength, laser spot size, pulse frequency etc. are the main factors that affect the fineness of electroless copper plating. By adjusting these parameters, the fineness of the copper plating was improved. X-ray energy spectrum and Auger electron spectroscopy results showed that after the laser scanning, both Cu^0 and Cu^(+1) appeared in the scanning area, revealing thus the mechanism of electroless copper plating for polyurethane-EDTA-Cu flexible cathodes.

磁约束飞秒激光诱导铜等离子体特性研究

磁约束飞秒激光诱导铜等离子体特性研究

Laser-induced plasmas in air studied using two-color interferometry

Temporally and spatially resolved density profiles of Cu atoms, electrons, and compressed air, from laser-induced copper plasmas in air, are measured using fast spectral imaging and two-color interferometry. From the intensified CCD images filtered by a narrow-band-pass filter centered at 515.32 nm, the Cu atoms expansion route is estimated and used to determine the position of the fracture surface between the Cu atoms and the air. Results indicate that the Cu atoms density at distances closer to the target (0–0.4 mm) is quite low, with the maximum density appearing at the edge of the plasma's core being ∼4.6 × 1024 m−3 at 304 ns. The free electrons are mainly located in the internal region of the plume, which is supposed to have a higher temperature. The density of the shock wave is (4–6) × 1025 m−3, corresponding to air compression of a factor of 1.7–2.5.