Laser-induced Forward Transfer Technique Research Articles

High-definition direct-print of metallic microdots with optical vortex induced forward transfer

We demonstrate high-definition, direct-printing of micron-scale metallic dots, comprised of close-packed gold nanoparticles, by utilizing the optical vortex laser-induced forward transfer technique. We observe that the spin angular momentum of the optical vortex, associated with circular polarization, assists in the close-packing of the gold nanoparticles within the printed dots. The printed dots exhibit excellent electrical conductivity without any additional sintering processes. This technique of applying optical vortex laser-induced forward transfer to metallic dots is an innovative approach to metal printing, which does not require additional sintering. It also serves to highlight new insights into light–matter interactions.

One-Step Non-Contact Additive LIFT Printing of Silver Interconnectors for Flexible Printed Circuits

The single-pass one-step method for printing conductive silver tracks on a glass surface, using the laser-induced forward transfer (LIFT) technique, was proposed, providing a unique opportunity for high-throughput printing of surface micro- and nanostructures with high electrical conductivity and positioning accuracy. This method was developed via our multi-parametric research, resulting in the selection of the optimal material, laser irradiation, and transfer conditions. Optical, scanning and transmission electron, and atomic force microscopy methods, as well as X-ray diffraction, were used to characterize the surface structure and phase state of the printed structures, while energy-dispersive X-ray and X-ray photoelectron microscopy were employed for their chemical microanalysis. Depending on the laser irradiation parameters, the specific electrical conductivity of the printed tracks varied from 0.18 to 83 kS/cm, approaching that of donor magnetron-sputtered films. This single-pass one-step method significantly facilitates fast, large-scale, on-demand local laser printing of metallic (sub)microcomponents of microelectronic devices.

Laser-induced forward transfer (LIFT) based bioprinting of the collagen I with retina photoreceptor cells

This study focuses on the 3D bioprinting of retina photoreceptor cells using a laser-induced forward transfer (LIFT) based bioprinting system. Bioprinting has a great potential to mimic and regenerate the human organoid system, and the LIFT technique has emerged as an efficient method for high-resolution micropatterning and microfabrication of biomaterials and cells due to its capability of creating precise, controlled microdroplets. In this study, the parameters for an effective femtosecond laser-based LIFT process for 3D bioprinting of collagen biomaterial were studied. Different concentrations of collagen I solutions were tested and 0.75 mg/ml to 1 mg/ml collagen Ⅰ was identified as the right concentration that can be transferred through the LIFT system. Then, retinal cone cells were mixed with collagen I and Dulbecco's Modified Eagle's Medium (DMEM) and printed drop-by-drop lines. Some important laser parameters such as pulse energy and pulse pick divider were experimented with to form a successful, smooth, high-resolution deposition. The cell viability in the bioink and printed droplet was measured at different time horizons. A general full factorial design of the experiment was used to analyze and observe the relationship between the droplet quality and the LIFT process parameters. Using 15 µJ and 16 µJ pulse energy, the cell-laden bioink was printed successfully. This research study will help to print other retinal neuron cells with collagen Ⅰ in the LIFT system and show the way of constructing layer-by-layer different cell lines that will help to fabricate the retina ultimately.

Digital laser-induced printing of MoS2

Abstract Due to their atomic-scale thickness, handling and processing of two-dimensional (2D) materials often require multistep techniques whose complexity hampers their large-scale integration in modern device applications. Here we demonstrate that the laser-induced forward transfer (LIFT) method can achieve the one-step, nondestructive printing of the prototypical 2D material MoS2. By selecting the optimal LIFT experimental conditions, we were able to transfer arrays of MoS2 pixels from a metal donor substrate to a dielectric receiver substrate. A combination of various characterization techniques has confirmed that the transfer of intact MoS2 monolayers is not only feasible, but it can also happen without incurring significant defect damage during the process. The successful transfer of MoS2 shows the broad potential the LIFT technique has in the emerging field of printed electronics, including printed devices based on 2D materials.

Printing via Laser-Induced Forward Transfer and the Future of Digital Manufacturing.

In the last decades, digital manufacturing has constituted the headline of what is starting to be known as the 'fourth industrial revolution', where the fabrication processes comprise a hybrid of technologies that blur the lines between fundamental sciences, engineering, and even medicine as never seen before. One of the reasons why this mixture is inevitable has to do with the fact that we live in an era that incorporates technology in every single aspect of our daily lives. In the industry, this has translated into fabrication versatility, as follows: design changes on a final product are just one click away, fabrication chains have evolved towards continuous roll-to roll processes, and, most importantly, the overall costs and fabrication speeds are matching and overcoming most of the traditional fabrication methods. Laser-induced forward transfer (LIFT) stands out as a versatile set of fabrication techniques, being the closest approach to an all-in-one additive manufacturing method compatible with virtually any material. In this technique, laser radiation is used to propel the material of interest and deposit it at user-defined locations with high spatial resolution. By selecting the proper laser parameters and considering the interaction of the laser light with the material, it is possible to transfer this technique from robust inorganic materials to fragile biological samples. In this work, we first present a brief introduction on the current developments of the LIFT technique by surveying recent scientific review publications. Then, we provide a general research overview by making an account of the publication and citation numbers of scientific papers on the LIFT technique considering the last three decades. At the same time, we highlight the geographical distribution and main research institutions that contribute to this scientific output. Finally, we present the patent status and commercial forecasts to outline future trends for LIFT in different scientific fields.

Separated nano jetting and micro jetting regimes by double-pulse irradiation of a metal film: towards multiscale printing.

The Double-Pulse (DP) version of the Laser-Induced Forward Transfer (LIFT) technique holds great potential to improve the resolution and flexibility of printing applications. In this study, we investigate the transfer of copper. A long laser pulse is first applied to melt thin copper films deposited on a transparent substrate, followed by an ultrashort laser pulse to initiate the transfer of the liquid material towards a receiver substrate. Time-resolved imaging experiments reveal that ejections from nanodrops to liquid jets with controllable diameters, from few micrometers down to the nanometers scale can be obtained with the control parameters of DP-LIFT. Comparing simulation and experiments we discuss how the ejection characteristics are governed by various factors including the shape, diameter and temperature of the melted pool created with the first long pulse. While the formation of microjets is due to the dynamical deformation of the melted film, as for the conventional LIFT process applied with liquid donors, the results indicate a different and distinct process for the formation of nanojets. We extrapolate from the observations a feature caused by the interaction of the shockwave, generated by the femtosecond laser irradiation, with the deformed surface of the pool. Ultimately, we establish the range of irradiation parameters leading to the observation of single separated microjets and nanojets. The latter are accompanied by nano printing demonstrations. Considering all accessible regimes together, a unique technological perspective is the possibility to achieve multi-scale printing from the same donor.

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 (LIFT) Technique as an Alternative for Assembly and Packaging of Electronic Components

Current trends in microelectronics chip bonding and assembly encompass ultra-fine pitch components with flexible form factors and advanced die-attach materials, which can sustain conformal strain without compromise in adhesion and reliability. These trends have highlighted the need for advanced microfrabrication technologies, which allow the on-demand digital fabrication of interconnections and die-attach bumps on chip carriers and interposers with challenging topographies. Laser printing, based on the laser induced forward transfer (LIFT) technique, has addressed such micromanufacturing challenges over the past decade. Several previous demonstrations of highly resolved and conformal interconnections for the bonding and packaging of micro and opto-electronic components are summarized in this paper. Latest advances in the laser printing and laser sintering of highly viscous nanopastes for achieving planar or three-dimensional (3D) structures consisting of Ag paste are demonstrated. The latter is achieved by stacking of arrays or bumps in a digital manner. The reported results verify that LIFT offers control over both the lateral and vertical dimensions. This control can facilitate the soldering process of heterogeneous components, whose pads have significant height and pitch dissimilarities. The applicability of LIFT in the fields of packaging and assembly of flexible and heterogeneous integration schemes, is further validated.

Selective powder feeding system in additive manufacturing using laser-induced forward transfer technique

In this study, we demonstrate a powder feeding system without a recoater for powder bed fusion-type additive manufacturing. The powder bed fusion system disposes a large quantity of powder, which is filled in the building container. To solve this problem, we developed a selective powder feeding system using laser-induced forward transfer technology. Our system comprised a donor film, laser component, and receiver substrate. The donor film was continuously moved from roll to roll, and the polymer powder was supplied on the lower side of the film with a rotating roller. The powder was transferred from the film surface to the receiver substrate, 3D object building area, by the irradiation of the laser beam with a wavelength of 532 nm. The laser beam was scanned over the scan area on the donor film. By continuously moving the donor film and receiver substrate, the powder layer was stacked on the receiver substrate. From the single-layer stacking experiment, we investigated that the gap between the donor film and receiver substrate strongly depended on the spreading of the powder. Moreover, by stacking 60 times, we acquired the rectangular-shaped powder block with a height of 10 mm. These results pave the way for developing an economical powder bed fusion system with reduced powder waste. • Additive manufacturing system with selective powder feeding was developed. • This system selectively feeds the powder to a 3D model or powder bed without contact by using LIFT technologies. • This selective powder feeder achieves a more economical AM strategy without exposing the powder to high temperatures. • Our results pave the way for developing an economical powder bed fusion system with reduced powder waste.

Optical and Morphological Properties of Silver Nanoparticles Synthesis by Laser Induced Forward Transfer Technique

Various methods could be employed to synthesize nanomaterials. In this work laser induced forward technology was used to synthesize silver nanoparticles. Silver nanomaterials were tested using different measuring instruments such as UV–vis diffuse (DRS), Atomic Force Microscopy (AFM), and optical Microscope to characterize features such as the optical and morphological properties of these nanoparticles. AFM results show that when the laser energy of the pulsed Nd: YAG laser increases, the diameter and roughness of produced AgNPs will be decreased for the same number of pulses and the air cavity between donner and acceptor. Also, results show that when laser energy is (300,400) mJ, the AgNPs diameters are (95.76,88.44) nm and the roughness are (7,6) nm respectively. While, results show that as laser pulses increase, structure to be rougher for different laser pulses and constant laser energy at 300 mJ the same behavior will be found when the laser energy becomes 400mJ.Finally, results show that the reflectance peaks of Ag NPs increase by decreasing the number of pulses to a maximum value of 467 at 2 pulses.

3D Printing at Micro-Level: Laser-Induced Forward Transfer and Two-Photon Polymerization.

Laser-induced forward transfer (LIFT) and two-photon polymerization (TPP) have proven their abilities to produce 3D complex microstructures at an extraordinary level of sophistication. Indeed, LIFT and TPP have supported the vision of providing a whole functional laboratory at a scale that can fit in the palm of a hand. This is only possible due to the developments in manufacturing at micro- and nano-scales. In a short time, LIFT and TPP have gained popularity, from being a microfabrication innovation utilized by laser experts to become a valuable instrument in the hands of researchers and technologists performing in various research and development areas, such as electronics, medicine, and micro-fluidics. In comparison with conventional micro-manufacturing methods, LIFT and TPP can produce exceptional 3D components. To gain benefits from LIFT and TPP, in-detail comprehension of the process and the manufactured parts’ mechanical–chemical characteristics is required. This review article discusses the 3D printing perspectives by LIFT and TPP. In the case of the LIFT technique, the principle, classification of derivative methods, the importance of flyer velocity and shock wave formation, printed materials, and their properties, as well as various applications, have been discussed. For TPP, involved mechanisms, the difference between TPP and single-photon polymerization, proximity effect, printing resolution, printed material properties, and different applications have been analyzed. Besides this, future research directions for the 3D printing community are reviewed and summarized.

Blister-based laser-induced forward transfer of 1D and 2D carbon nanomaterials

The possibility of laser printing of single-walled carbon nanotubes (SWCNTs) and graphene via blister-based laser-induced forward transfer technique is demonstrated. Laser radiation with optimized fluence, that is absorbed in a thin aluminium film, causes its local evaporation and blistering without rupture, which leads to the ejection of carbon nanomaterial from the donor to the receiving substrate. The use of preliminary cutting of the donor layer into square pixels allows printing SWCNTs while maintaining their shape. Raman analysis indicates the transfer of carbon nanomaterials without significant degradation.

Fluorescence enhanced BA-LIFT for single cell detection and isolation

Laser bioprinting is a term that refers to a group of laser-based techniques for printing living cells with high precision and good viability. Most of these techniques are based on modifications of the standard laser induced forward transfer technique (LIFT). When it comes to printing living material, direct laser irradiation should be avoided, therefore an indirect LIFT technique comprising an energy absorption layer should be used. This work presents a blister actuated-LIFT (BA-LIFT) technique which uses a commercial polyimide tape as a uniform energy absorption layer. To increase the potential of the technique for cell selection and printing accuracy, we take advantage of the high optical transmission of the polyimide layer to implement an in-line fluorescence and conventional imaging vision system coaxial with the laser path. With this system and using the appropriate staining methodology it is possible to track and identify different cell types, selecting those to be transferred and tracking cell survival both in the donor and acceptor substrates. We studied the BA-LIFT printability map for sodium alginate and methylcellulose hydrogels in the fluence range from 6.1 to 2.0 J cm−2 together with the cell viability assessment measured by our fluorescence system. The study has revealed that less concentrated, therefore less viscose hydrogel shows better results with lower fluences, whereas hydrogels with higher concentrations present better results at higher fluences. Also, at low fluences 98 % of cell viability was obtained, besides both primary cells and cell lines keep their integrity, proliferating and functional activity. The technique was tested by tracking and targeting mouse hematopoietic progenitor stem cells transferred to assess colony forming units; moreover, natural killer cells were isolated and its activation in a stimulation media was tracked with the fluorescence system.

Investigation on high speed laser printing of silver nanoparticle inks on flexible substrates

The ever-increasing demand for more efficient, cost- and time-effective electronics required in production-grade technology, impels the research in the field of printed electronics. Laser-induced forward transfer (LIFT) technique meets the requirements for precise deposition and high resolution components, however further research has to be conducted in order to improve the process’ speed and reproducibility. In this work, laser printing of silver (Ag) nanoparticle lines on PEN substrate at high repetition rates (10–40 kHz) is introduced and an investigation on the factors that affect the printing results, including the experimental setup’s parameters and inks’ rheological characteristics, is conducted. Specifically, a high-speed imaging setup is employed in order to study the liquid bubble formation and jet expansion, for four Ag nanoparticle inks of different viscosities and four different repetition rates. At the same time, different values of donor-receiver distance and scanning step are applied, in order to succeed optimum lines. The results indicate that, for high repetition rates, best quality lines derive from high viscosity inks when the distance between the donor and the receiver is relatively small.

Overlapping Limitations for ps-Pulsed LIFT Printing of High Viscosity Metallic Pastes

Laser-induced forward transfer (LIFT) technique has been used for printing a high viscosity (250 Pa·s) commercial silver paste with micron-size particles (1–4 µm). Volumetric pixels (voxels) transferred using single ps laser pulses are overlapped in order to obtain continuous metallic lines. However, interference problems between successive voxels is a major issue that must be solved before obtaining lines with good morphologies. The effects of the laser pulse energy, thickness of the donor paste film, and distance between successive voxels on the morphology of single voxels and lines are discussed. Due to the high viscosity of the paste, the void in the donor film after a printing event remains, and it negatively affects the physical transfer mechanism of the next laser pulses. When two laser pulses are fired at a short distance, there is no transfer at all. Only when the pulses are separated by a distance long enough to avoid interference but short enough to allow overlapping (≈100 µm), is it possible to print continuous lines in a single step. Finally, the knowledge obtained has allowed the printing of silver lines at high speeds (up to 60 m/s).

Simulation of direct and blister-assisted laser-induced forward transfer techniques

In Laser-Induced Forward Transfer (LIFT), fluid motion is a complex hydrodynamic phenomenon. In the case of LIFT of high-viscosity fluids, the formation of a stable hollow column between the donor and the acceptor substrates takes place, whereas the transference of low-viscosity fluids through Blister-Assisted LIFT (BA-LIFT) leads to secondary effects that have not been already explained, such as secondary jets or bulgy shapes. In this work, every reported regime has been modeled through a Phase Field FEM model for both LIFT and BA-LIFT.

Deposition of Fine Linewidth Silver Layer using a Modified Laser-induced Forward Transfer Technique

This paper reports the deposition of a metal line using a multilayer stack and laser-induced forward transfer (LIFT) using a low cost continuous wave blue laser with a wavelength of 450 nm. The donor structure was composed of a light-to-heat (LTH) layer, a release layer, and a transfer layer in series. Amorphous silicon as the LTH layer absorbs photon energy and converts it to heat. A release layer was melted so that a silver transfer layer would be transferred to the receiver substrate. The transferred silver layer showed reasonable physical and electrical characteristics. A low cost fine linewidth metal layer could be achieved using this modified LIFT technique and blue laser.

Laser printing of microbial systems: effect of absorbing metal film.

Recently, it was shown that laser-induced forward transfer (LIFT) technology and the laser engineering of microbial systems (LEMS) technique (based on LIFT method) are effective for isolation of micro-organisms from different complex substrates. These techniques frequently utilize Au as an absorbing layer material. The purpose of this study was to investigate the influence of absorbing film materials (Au, Ti and Cr) on the effectiveness of laser printing of micro-organisms to improve LEMS and LIFT techniques. It was shown that application of Ti and Cr absorbing layers activates bacterial growth after laser printing and is significantly more effective in comparison to Au films, which actually show a suppressing effect on bacterial cells. Results of this study can be applied for LEMS and LIFT protocols for improving bacterial isolation and microbial growth. SIGNIFICANCE AND IMPACT OF THE STUDY: Laser-induced forward transfer technique (LIFT) is currently used for printing of micro-organisms and in biosensor techniques, for single-cell isolation, and for culturing of micro-organisms from complex substrates. We have studied the influence of absorbing film materials (Au, Ti and Cr) on the effectiveness laser printing of micro-organisms. It was shown that application of Ti and Cr absorbing layers activates bacterial growth and is more effective in LIFT compared to Au films, which actually have a suppressive effect on bacteria cells. The results can improve LIFT protocols for bacteria isolation and culturing of microbial systems.

Effect of Laser Fluence on a Microarray Droplets Micro-Organisms Cells by LIFT Technique

Laser Induced Forward Transfer (LIFT) is one important method to fabricate microstructures, and it has been widely used in direct-print many materials with a high degree of spatial re- solution. In present work, The results of the application of the LIFT on micro-organism cells like (Yeast and Escherichia coli (E.coli))transfer, a microarray droplets have been created from liquid thin film coated titanium Oxide thin film and study the laser fluence on the droplet transfer with checking the viability of the transferred cells assessing the potential of laser. Titanium Oxide thin films average thickness less than 250 nm, were deposited on glass substrate. For characterization, Scanning Electron Microscope was exercised to check the integrity of micro-organisms cells ( Yeast and E.coli ) which showed maintenance during the process. The MacConkey agriculture media was used to test viability of Yeast and E.coli cells. Further, studying the optimum environments to preserve viability of the transferred yeast cells, these conditions were at laser fluence of 10mJ/cm2 and 150µm distance between donor and receptor layers.

Three-Dimensional Bioprinting: Emerging Technology in Cardiovascular Medicine.

With recent advances made in research, we are at a revolutionary and challenging period for 3-dimensional (3D) bioprinting, where a single device (printer) can deposit and layer building blocks of bioink (a composition of cells and structural scaffolds). A key advantage of 3D bioprinting is the ability to produce complex designs from a computer-aided file, making it possible to generate identical copies of patient tissues and organs within 3D space. A wide range of biomaterials are used for 3D printing; similarly, different types of bioprinters have been developed to deposit bioink. Thermal inkjet utilizes a thermal resistor and heat to force down the printing material. Piezoelectric inkjet uses the same approach with a piezoelectric crystal. 3D printers with microextrusion technologies use direct mechanical energy to deposit the printing material. Acoustic picoliters, which are nozzleless bioprinters, use a liquid reservoir that can contain cells as well as a variety of biological materials underneath a series of interdigitized acoustic rings. By adjusting the frequency of acoustic pulse, the size of the droplet can be changed and reduced to sizes that contain single cells with higher cell viabilities. Laser-induced forward transfer also uses a nozzleless approach. Using a series of laser pulses and alternating layers of absorption gelatins, laser-induced forward transfer techniques aim to deliver printing material to a substrate that can result in <95% cell viability. Cardiac valve replacement therapies include the use of mechanical or biological heart valves. …