Laser-induced Forward Transfer Research Articles

Glass marking by laser transfer implantation (LTI) of plasmonic nanoparticles

Gold nanoparticles in the near surface volume of glass are generated by combining laser-induced forward transfer (LIFT) and laser implantation into one single laser process called laser transfer implantation (LTI). Nanosecond pulses of a KrF excimer laser at 248 nm wavelength are used to transfer and implant the material from a gold- coated, UV-transparent polymer film into soda lime, borofloat, and flint glasses. The process can be applied for marking glass with colored labels consisting of spectrally selectively absorbing plasmonic nanoparticles.

Laser-Induced Forward Transfer of Silver Nanoparticles for a Black Metal Absorber

Plasmonic nanostructures emerged as an appealing approach for black metal absorbers (BMAs) to provide significant light absorption. We present the simple and rapid fabrication of BMAs using laser-induced forward transfer of silver nanoparticles (AgNPs). Randomly distributed plasmon silver nanostructures at a multiscale were produced simultaneously during laser transfer, providing significant light absorption and antireflection features. The laser-transferred BMAs exhibit excellent absorption capacity of a value over 96% and a minimum reflection of 0.38%. A high scanning speed of 10 m/s was used that can complete the laser-induced forward transfer (LIFT) process within 2 s for a 1 cm2 area. The nearfield light confinement is discussed in terms of the morphology of the obtained nanostructures. Photothermal conversion with macroscale temperature rising was demonstrated for the LIFT process is an effective method for the industrial production of BMAs with excellent absorption capacity.

Hybrid superhydrophobic/hydrophilic patterns deposited on glass by laser-induced forward transfer method for efficient water harvesting

In recent years, the combination of factors such as growing population and global climate change has resulted in freshwater shortages. Therefore, water harvesting from the atmospheric fog in order to produce freshwater supply inspired by nature has received much attention. The water harvesting capability of the creatures is significantly based on the combination of both wettability states on their surfaces. In this study, a facile physicochemical hybrid method was used for the fabrication of glass surfaces with contrast wettability. First, fractal and regular repeated geometric patterns were deposited on a glass substrate using brass sheet as donor material by laser induced forward transfer (LIFT) method. Subsequently, stearic acid (SA) treatment was used to convert the wettability of the superhydrophilic (SHL) deposited patterns on glass to superhydrophobic. In order to investigate the effect of the shape of designed patterns on glass surfaces in the water harvesting efficiency, the amount of collected water for a period of time from untreated hydrophilic (HL) glass, superhydrophobic (SHB) glass and hybrid superhydrophobic/hydrophilic (SHB-HL) surfaces were measured. The obtained results indicate that the hybrid of superhydrophobic and hydrophilic regions and selecting the optimal pattern can improve the water harvesting performance by up to 300%.

Field Electron Emission from Crumpled CVD Graphene Patterns Printed via Laser-Induced Forward Transfer.

A new approach to the fabrication of graphene field emitters on a variety of substrates at room temperature and in an ambient environment is demonstrated. The required shape and orientation of the graphene flakes along the field are created by the blister-based laser-induced forward transfer of CVD high-quality single-layer graphene. The proposed technique allows the formation of emitting crumpled graphene patterns without losing the quality of the initially synthesized graphene, as shown by Raman spectroscopy. The electron field emission properties of crumpled graphene imprints 1 × 1 mm2 in size were studied. The transferred graphene flakes demonstrated good adhesion and emission characteristics.

Indium Tin Oxide-Free Inverted Organic Photovoltaics Using Laser-Induced Forward Transfer Silver Nanoparticle Embedded Metal Grids.

Laser-induced forward transfer (LIFT) printing has emerged as a valid digital printing technique capable of transferring and printing a wide range of electronic materials. In this paper, we present for the first time LIFT printing as a method to fabricate silver (Ag) nanoparticle (np) grids for the development of indium tin oxide (ITO)-free inverted PM6:Y6 nonfullerene acceptor organic photovoltaics (OPVs). Limitations of the direct use of LIFT-printed Ag np grids in inverted ITO-free OPVs are addressed through a Ag grid embedding process. The embedded laser-printed Ag grid lines have high electrical conductivity, while the Ag metal grid transparency is varied by altering the number of Ag grid lines within the inverted OPVs’ ITO-free bottom electrode. Following the presented Ag-grid embedding (EMP) process, metal-grid design optimizations, and device engineering methods incorporating an EMB-nine-line Ag np grid/PH500/AI4083/ZnO bottom electrode, we have demonstrated inverted ITO-free OPVs incorporating laser-printed Ag grids with 11.0% power conversion efficiency.

Parametric investigations on laser-induced forward transfer based micro-3D printing of NiTi alloy

ABSTRACT Laser-induced forward transfer (LIFT)-based micro-3D printing is a process in which the pulsed laser beam is used to transfer the material from thin-film deposited substrate (donor substrate) to the target substrate by inducing a high-pressure gas between the thin film and substrate. This study is focused on printing NiTi shape memory alloy using micro-3D printing for the continuous line pattern deposition. NiTi material is coated in the thin film via sputtering process, and the line pattern is deposited by CO2 laser at a wavelength of 10.6 μm for the transfer process. Numerical simulation is performed to analyze the interface temperature between the thin film and sacrificial layer. The optimized laser fluences for 1.5 μm and 3 μm sacrificial layer thicknesses are 770 mJ/cm2 and 2300 mJ/cm2, respectively. The printed pixel size decreases with an increase in the overlap, and the adhesion of pixels (with substrate) increases with an increase in the target substrate temperature. The transferred pixels are characterized using energy dispersive spectroscopy analysis and X-ray diffraction techniques. The study paves a way for the successful micro-3D printing of NiTi for potential microdevice fabrication.

Automated Laser-Transfer Synthesis of High-Density Microarrays for Infectious Disease Screening.

Laser-induced forward transfer (LIFT) is a rapid laser-patterning technique for high-throughput combinatorial synthesis directly on glass slides. A lack of automation and precision limits LIFT applications to simple proof-of-concept syntheses of fewer than 100 compounds. Here, an automated synthesis instrument is reported that combines laser transfer and robotics for parallel synthesis in a microarray format with up to 10 000 individual reactions cm- 2 . An optimized pipeline for amide bond formation is the basis for preparing complex peptide microarrays with thousands of different sequences in high yield with high reproducibility. The resulting peptide arrays are of higher quality than commercial peptide arrays. More than 4800 15-residue peptides resembling the entire Ebola virus proteome on a microarray are synthesized to study the antibody response of an Ebola virus infection survivor. Known and unknown epitopes that serve now as a basis for Ebola diagnostic development are identified. The versatility and precision of the synthesizer is demonstrated by in situ synthesis of fluorescent molecules via Schiff base reaction and multi-step patterning of precisely definable amounts of fluorophores. This automated laser transfer synthesis approach opens new avenues for high-throughput chemical synthesis and biological screening.

Inside Cover

The ability to sort yeast cells is important for diverse applications in the industry and research. We determined the aging level of yeast by the fluorescence lifetime imaging microscopy (FLIM) by an endogenous fluorophore NAD(P)H, which was label-free and non-invasive. Young and active yeast cells were sorted by the laser-induced forward transfer (LIFT) system at the single cell level. The high viability of sorted cells was achieved. Further details can be found in the article by Yawei Kong, Yinping Zhao, Yao Yu, Wenhua Su, Zhijia Liu, Yiyan Fei, Jiong Ma, and Lan Mi (e202100344)

Facile Modification of Flexible Electrodes via Laser Transfer.

In this work, we report the modification of commercially available electrochemical electrodes with tin oxide (SnO2) and Pd doped SnO2 (Pd-SnO2) via pulsed laser-induced forward transfer (LIFT). The pulsed light irradiation working as in situ pulsed photo-thermal treatment allows for the transfer of SnO2 and Pd-SnO2 from UV absorbing metal complex precursors onto flexible, commercially available screen-printed electrodes. The laser transfer conditions are optimized and the material transferred under different conditions is evaluated morphologically and chemically, and its functionality is tested against the detection of copper ions. For example, by applying laser fluences in the range 100–250 mJ/cm2, the shape and the size of the transferred features ranges from nano-polyhedrons to near corner-grown cubic Pd-SnO2 or near cubic Pd-SnO2. In addition, the EDX analysis is consistent with the XPS findings, i.e., following laser transfer, Pd amounts lower than 0.5% are present in the Pd-SnO2 pixels. First sensing tests were carried out and the transferred Pd-SnO2 proved to enhance the cathodic peak when exposed to Cu(II) ions. This photo-initiated fabrication technology opens a promising way for the low-cost and high-throughput manufacturing of metal oxides as well as for electrodes for heavy metal ion detection.

Theoretical Modeling and Experimental Studies of Ultra-Thin Chip Transfer in Laser-Induced Forward Transfer

In order to understand and optimize the complex transfer process of ultrathin chip in laser-induced forward transfer (LIFT), a substrate–dynamic release layer (DRL)–chip structure is proposed, and a finite-element and cohesive zone model (CZM) is developed to investigate the laser ejecting needle formation and ultrathin chip peeling evolution, which is used to help analyze the impact transfer behavior of ultrathin chip in LIFT. The model considers laser absorption, conduction, volumetric expansion, and crack propagation in the substrate–DRL–chip structure. The results of the model indicate that longer laser irradiation time could produce larger maximum vapor pressure and chip transfer velocity. In addition, there are three transfer conditions in LIFT: no transfer, successful transfer, and impact fracture, which are sensitive to laser fluence. In order to achieve successful ultrathin chip transfer, an LIFT window is established and provides guidance for the appropriate laser fluence in LIFT.

Assessing Polymer-Surface Adhesion with a Polymer Collection.

Polymer modification plays an important role in the construction of devices, but the lack of fundamental understanding on polymer-surface adhesion limits the development of miniaturized devices. In this work, a thermoplastic polymer collection was established using the combinatorial laser-induced forward transfer technique as a research platform, to assess the adhesion of polymers to substrates of different wettability. Furthermore, it also revealed the influence of adhesion on dewetting phenomena during the laser transfer and relaxation process, resulting in polymer spots of various morphologies. This gives a general insight into polymer-surface adhesion and connects it with the generation of defined polymer microstructures, which can be a valuable reference for the rational use of polymers.

Laser-Induced Forward Transfer Printing on Microneedles for Transdermal Delivery of Gemcitabine.

Cancer treatment with chemotherapeutic drugs remains to be challenging to the physician due to limitations associated with lack of efficacy or high toxicities. Typically, chemotherapeutic drugs are administered intravenously, leading to high drug concentrations that drive efficacy but also lead to known side effects. Delivery of drugs through transdermal microneedles (MNs) has become an important alternative treatment approach. Such delivery options are well suited for chemotherapeutic drugs in which sustained levels would be desirable. In the context of developing a novel approach, laser-induced forward transfer (LIFT) was applied for bioprinting of gemcitabine (Gem) to coat polymethylmethacrylate MNs. Gem, a chemotherapeutic agent used to treat various types of cancer, is a good candidate for MN-assisted transdermal delivery to improve the pharmacokinetics of Gem while reducing efficiency limitations. LIFT bioprinting of Gem for coating of MNs with different drug amounts and successful transdermal delivery in mice is presented in this study. Our approach produced reproducible, accurate, and uniform coatings of the drug on MN arrays, and on in vivo transdermal application of the coated MNs in mice, dose-proportional concentrations of Gem in the plasma of mice was achieved. The developed approach may be extended to several chemotherapeutics and provide advantages for metronomic drug dosing.

Development and Experimental Assessment of a Model for the Material Deposition by Laser-Induced Forward Transfer

The potential to deposit minute amounts of material from a donor to an acceptor substrate at precise locations makes laser-induced forward transfer (LIFT) a frequently used tool within different research fields, such as materials science and biotechnology. While many different types of LIFT exist, each specialized LIFT application is based on a different underlying transfer mechanism, which affects the to-be-transferred materials in different ways. Thus, a characterization of these mechanisms is necessary to understand their limitations. The most common investigative methods are high-speed imaging and numerical modeling. However, neither of these can, to date, quantify the material deposition. Here, analytical solutions are derived for the contact-based material deposition by LIFT, which are based on a previously observed equilibrium state. Moreover, an analytical solution for the previously unrecognized ejection-based material deposition is proposed, which is detectable by introducing a distance between the donor and acceptor substrates. This secondary mechanism is particularly relevant in large scale production, since each deposition from a donor substrate potentially induces a local distance between the donor and acceptor substrates.

Single cell sorting of young yeast based on label-free fluorescence lifetime imaging microscopy.

Saccharomyces cerevisiae is an attractive organism used in the fermentation industry and is an important model organism for virus research. The ability to sort yeast cells is important for diverse applications. Replicative aging of Saccharomyces Cerevisiae is accompanied by metabolic changes that are related to an essential coenzyme, reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H). Here, a single cell sorting method based on fluorescence lifetime imaging microscopy (FLIM) and laser-induced forward transfer (LIFT) was implemented for the first time. The aging level of yeast was determined based on the FLIM by NAD(P)H, which was a label-free and noninvasive method for studying individual cells. Then, young and active yeast cells were sorted by the LIFT system at the single cell level. During the entire experiment, a sterile and humid environment was maintained to ensure the activity of cells. The high viability of sorted cells was achieved by the LIFT combining with FLIM.

On-the-fly bare die bonding based on laser induced forward transfer (LIFT)

Die bonders are faster than ever at 42,000 units per hour (UPH) these days. However, the die transfer process is often the limiting time constraint due to the inertia of the mechanical actuators. In addition, the mechanical die ejection physically limits the minimum possible die dimensions. To overcome these limitations we developed a laser-induced on-the-fly bare die bonding technology. Experimental results verify, this technology significantly accelerates the die ejection process and enables up to 108,000 UPH. Further, this technology opens up possibilities for efficient and novel concepts for automatable production, e.g. for flexible ultra-thin wafers.

Printing Regime for Single Metal Microdroplet Deposition in Laser-Induced Forward Transfer

Printing Regime for Single Metal Microdroplet Deposition in Laser-Induced Forward Transfer

Liquid Crystal Doped Photopolymer Microlenses Printed by a Simpler and Cleaner Laser-Induced Forward Transfer Process

Liquid Crystal Doped Photopolymer Microlenses Printed by a Simpler and Cleaner Laser-Induced Forward Transfer Process

Hybrid Superhydrophobic/Hydrophilic Patterns Deposited on Glass by Laser-Induced Forward Transfer Method for Efficient Water Harvesting

Hybrid Superhydrophobic/Hydrophilic Patterns Deposited on Glass by Laser-Induced Forward Transfer Method for Efficient Water Harvesting

Laser induced forward transfer of high viscosity silver paste on double groove structure

Front side metallization is a critical process for the production of solar cells; current research focuses on downsizing finger electrodes and lowering printing costs. Laser-induced forward transfer (LIFT) has the advantages of non-contact and non-mask, which can reduce wafer breakage and silver paste usage during front side metallization. Although LIFT is beneficial in reducing printing costs, it is difficult to further downsize fingers electrodes. In this study, a silicon wafer with a laser-etched double groove structure was adopted as the acceptor to increase the printing resolution of LIFT. During the transfer process, contact between silver paste film and acceptor can only occur in the narrow area between the double grooves. Since the contact area is restricted, the width of the printed line will not exceed the narrow area. This approach improves printing resolution while preserving non-contact and non-mask characteristics. The lines printed have an average width of 30.5 μm and an average aspect ratio of 0.97. Furthermore, the line’s width will not be affected by fluctuations in laser fluence within a specific laser fluence interval. The research with different viscosities revealed four distinct transfer regimes. Through a visual observation system, the donor removal processes of different transfer regimes were observed. The experimental results show that only the sharp-shaped line transfer can achieve high-resolution lines, and the optimal results can be obtained only at a viscosity of 25 Pa·s. Finally, double pulses transfer was adopted to address the issue of excessive line thickness fluctuations.

Laser printing of large-scale metal micro/nanoparticle array: Deposition behavior and microstructure

In this study, a novel printing process is proposed to efficiently fabricate a large-scale micro/nanoparticle array via laser-induced forward transfer of femtoliter metal voxels. A sputtering metal film with sub-micrometer thickness was initially patterned to an independent voxel array using a picosecond laser. Then, an ultraviolet nanosecond laser induced the voxel transfer from the donor substrate to the receiver entirely after it was irradiated by a single laser pulse. The results indicated that single laser irradiation can print a microparticle array that covers an area of several millimeters. The printed microparticle size varied from 5 μm to 580 nm. Furthermore, the proposed printing process exhibited high controllability by adjusting the voxel volume. The morphology of the cross section of the printed copper microparticles exhibited a lower porosity and oxidation state, and ultrafine nanograins were generated within an amorphous shell. The location deviations of the printed microparticles obeyed the chi-square distribution with a mean value of 1 μm. Moreover, the proposed process can avoid the satellite microdroplets and debris for reducing the resolution because unstable jetting and microdroplet separation are eliminated. The proposed approach enables the printing of a large-scale microstructure array with high efficiency and flexibility.