RESUMEN

Laser-induced forward transfer is a contactless, nozzle free process which enables accurate, precise and fast development of 3D structures. However, a number of shortcomings such as shockwave generation, poor adhesion to receiver substrates and uniform depositions limit LIFT to be utilized. Therefore, this research tends to put forward easy and effective solutions for successful mitigation of the LIFT limitations. Receiver surface modifications and low-pressure conditions are introduced through laser surface texturing (LST) and a vacuum pump. A number of textures and orientations are investigated for determining the optimal copper (Cu) deposition. Furthermore, utilization of the same laser system for LST enables the manufacturing process cost and time effective. In addition to Cu depositions, additive layers of silver (Ag) and platinum (Pt) are deposited. Finally, Ag and Pt micropillars are fabricated on their respective additive layers leading to formation of Cu-Ag and Cu-Pt alloys structure. Subsequently, electrical and material characterizations are made to validate for potential applications. Experimental evidence shows greater adhesion with electrical properties for LST-based LIFT in low pressure conditions. Finally, an energy analysis is performed based on theoretical and finite element methods (FEM) to gain greater insights into mechanics of the LIFT process.

RESUMEN

BACKGROUND: The cultivation, analysis, and isolation of single cells or cell cultures are fundamental to modern biological and medical processes. The novel LIFTOSCOPE technology aims to integrate analysis and isolation into one versatile, fully automated device. METHODS: LIFTOSCOPE's three core technologies are high-speed microscopy for rapid full-surface imaging of cell culture vessels, AI-based semantic segmentation of microscope images for localization and evaluation of cells, and laser-induced forward transfer (LIFT) for contact-free isolation of cells and cell clusters. LIFT transfers cells from a standard microtiter plate (MTP) across an air gap to a receiver plate, from where they can be further cultivated. The LIFT laser is integrated into the optical path of an inverse microscope, allowing to switch quickly between microscopic observation and cell transfer. RESULTS: Tests of the individual process steps prove the feasibility of the concept. A prototype setup shows the compatibility of the microscope stage with the LIFT laser. A specifically designed MTP adapter to hold a receiver plate has been designed and successfully used for material transfers. A suitable AI algorithm has been found for cell selection. CONCLUSION: LIFTOSCOPE speeds up cell cultivation and analysis with a target process time of 10 minutes, which can be achieved if the cell transfer is sped up using a more efficient path-finding algorithm. Some challenges remain, like finding a suitable cell transfer medium. SIGNIFICANCE: The LIFTOSCOPE system can be used to extend existing cell cultivation systems and microscopes for fully automated biotechnological applications.

RESUMEN

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.

RESUMEN

Laser-induced forward transfer (LIFT) is a useful technique for bioprinting using gel-embedded cells. However, little is known about the stresses experienced by cells during LIFT. This paper theoretically and experimentally explores the levels of laser pulse irradiation and pulsed heating experienced by yeast cells during LIFT. It has been found that only 5% of the cells in the gel layer adjacent to the absorbing Ti film should be significantly heated for fractions of microseconds, which was confirmed by the fact that a corresponding population of cells died during LIFT. This was accompanied by the near-complete dimming of intracellular green fluorescent protein, also observed in response to heat shock. It is shown that microorganisms in the gel layer experience laser irradiation with an energy density of ~0.1-6 J/cm2. This level of irradiation had no effect on yeast on its own. We conclude that in a wide range of laser fluences, bioprinting kills only a minority of the cell population. Importantly, we detected a previously unobserved change in membrane permeability in viable cells. Our data provide a wider perspective on the effects of LIFT-based bioprinting on living organisms and might provide new uses for the procedure based on its effects on cell permeability.

Asunto(s)

Bioimpresión , Bioimpresión/métodos , Recuento de Células , Rayos Láser , Luz , Saccharomyces cerevisiae

RESUMEN

Laser-based techniques for printing cells onto different substrates with high precision and resolution present unique opportunities for contributing to a wide range of biomedical applications, including tissue engineering. In this study, laser-induced forward transfer (LIFT) printing was employed to rapidly and accurately deposit patterns of cancer cells in a non-contact manner, using two different wavelengths, 532 and 355 nm. To evaluate the effect of LIFT on the printed cells, their growth and DNA damage profiles were assessed and evaluated quantitatively over several days. The damaging effect of LIFT-printing was thoroughly investigated, for the first time at a single cell level, by counting individual double strand breaks (DSB). Overall, we found that LIFT was able to safely print patterns of breast cancer cells with high viability with little or no heat or shear damage to the cells, as indicated by unperturbed growth and negligible gross DNA damage.

RESUMEN

Femtosecond laser pulses have been successfully used for film-free single-cell bioprinting, enabling precise and efficient selection and positioning of individual mammalian cells from a complex cell mixture (based on morphology or fluorescence) onto a 2D target substrate or a 3D pre-processed scaffold. In order to evaluate the effects of higher pulse durations on the bioprinting process, we investigated cavitation bubble and jet dynamics in the femto- and picosecond regime. By increasing the laser pulse duration from 600 fs to 14.1 ps, less energy is deposited in the hydrogel for the cavitation bubble expansion, resulting in less kinetic energy for the jet propagation with a slower jet velocity. Under appropriate conditions, single cells can be reliably transferred with a cell survival rate after transfer above 95% through the entire pulse duration range. More cost efficient and compact laser sources with pulse durations in the picosecond range could be used for film-free bioprinting and single-cell transfer.

RESUMEN

Laser-induced forward transfer for high-viscosity-of Pa·s-pastes differ from standard LIFT processes in its dynamics. In most techniques, the transference after setting a great gap does not modify the shape acquired by the fluid, so it stretches until it breaks into droplets. In contrast, there is no transferred material when the gap is bigger than three times the paste thickness in LIFT for high-viscosity pastes, and only a spray is observed on the acceptor using this configuration. In this work, the dynamics of the paste have been studied using a finite-element model in COMSOL Multiphysics, and the behavior of the paste varying the gap between the donor and the acceptor substrates has also been modeled. The paste bursts for great gaps, but it is confined when the acceptor is placed close enough. The obtained simulations have been compared with a previous work, in which the paste structures were photographed. The analysis of the simulations in terms of speed allows for predicting the burst of the paste-spray regime-and the construction of a printability map regarding the gap between the substrates.

RESUMEN

Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, a thermocouple with a thickness of 10 µm and a height of 250 µm, consisting of platinum and gold pillars is demonstrated. Multimaterial LIFT enables manufacturing in the micrometer to millimeter range, i.e., between lithography and other 3D printing technologies.