Laser Microprinting of Transparent and Weakly Absorbing Solutions

A laser-based technique for printing transparent andweakly absorbing liquids is developed. Its principleof operation relies in the tight focusing of shortlaser pulses inside the liquid and close to its freesurface, in such a way that the laser radiation isabsorbed in a tiny volume around the beam waist,with practically no absorption in any other locationalong the beam path. If the absorbed energyovercomes the optical breakdown threshold, acavitation bubble is generated, and its expansionresults in the propulsion of a small fraction of liquidwhich can be collected on a substrate, leading to theprinting of a microdroplet for each laser pulse. Thetechnique does not require the preparation of theliquid in thin film form, and its forward mode ofoperation imposes no restriction concerning theoptical properties of the substrate. We demonstratethat the technique is capable of printingmicrodroplets with good resolution, reproducibilityand control, and analyze the influence of the mainprocess parameters. The mechanisms of liquidprinting are also investigated: time-resolvedimaging provides a clear picture of the dynamics ofliquid transfer which allows understanding the mainfeatures observed in the printed droplets

Laser-induced forward transfer of single-walled carbon nanotubes

The objective of this work is the application of laser-induced forward transfer (LIFT) for the fabrication of chemiresistor sensors. The receiver substrate is an array with metal electrodes and the active materials placed by LIFT are single-walled carbon nanotubes (SWCNT). The functionality of such sensors depends on the geometry of the active material onto the metallic electrodes. First the best geometry for the sensing materials and electrodes was determined, including the optimization of the process parameters for printing uniform pixels of SWCNT onto the sensor electrodes. The sensors were characterized in terms of their sensing characteristics, i.e., upon exposure to ammonia, proving the feasibility of LIFT

Two Engineered OBPs with opposite temperature-dependent affinities towards 1-aminoanthracene

Engineered odorant-binding proteins (OBPs) display tunable binding affinities triggered by temperature alterations. We designed and produced two engineered proteins based on OBP-I sequence: truncated OBP (tOBP) and OBP::GQ20::SP-DS3. The binding affinity of 1-aminoanthracene (1-AMA) to these proteins revealed that tOBP presents higher affinity at 25°C (kd=0.45M) than at 37°C (kd=1.72M). OBP::GQ20::SP-DS3 showed an opposite behavior, revealing higher affinity at 37°C (kd=0.58M) than at 25°C (kd=1.17M). We set-up a system containing both proteins to evaluate their temperature-dependent binding. Our data proved the 1-AMA differential and reversible affinity towards OBPs, triggered by temperature changes. The variations of the binding pocket size with temperature, confirmed by molecular modelling studies, were determinant for the differential binding of the engineered OBPs. Herein we described for the first time a competitive temperature-dependent mechanism for this class of proteins.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684). A.R. and F.G. thank FCT for funding their scholarships with the references SFRH/BPD/98388/2013 and SFRH/BD/114684/2016, respectively. T.G.C. thanks senior position funded by the European Union through the European Regional Development Fund (ERDF) under the Competitiveness Operational Program (COP-A1-A1.1.4-E nr.30/01.09.2016). C.S. thanks to the BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Access to computing resources funded by the Project "Search-ON2: Revitalization of HPC infrastructure of UMinho" (NORTE-07-0162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF), is also gratefully acknowledged.info:eu-repo/semantics/publishedVersio

Laser-induced forward transfer of single-walled carbon nanotubes

The objective of this work is the application of laser-induced forward transfer (LIFT) for the fabrication of chemiresistor sensors. The receiver substrate is an array with metal electrodes and the active materials placed by LIFT are single-walled carbon nanotubes (SWCNT). The functionality of such sensors depends on the geometry of the active material onto the metallic electrodes. First the best geometry for the sensing materials and electrodes was determined, including the optimization of the process parameters for printing uniform pixels of SWCNT onto the sensor electrodes. The sensors were characterized in terms of their sensing characteristics, i.e., upon exposure to ammonia, proving the feasibility of LIFT.ISSN:0947-8396ISSN:1432-0630ISSN:0340-379

Deposition and characterization of lines printed through laser-induced forward transfer

The possibility of printing two-dimensional micropatterns of biomolecule solutions is of great interest in many fields of research in biomedicine, from cell-growth and development studies to the investigation of the mechanisms of communication between cells. Although laser-induced forward transfer (LIFT) has been extensively used to print micrometric droplets of biological solutions, the fabrication of complex patterns depends on the feasibility of the technique to print micron-sized lines of aqueous solutions. In this study we investigate such a possibility through the analysis of the influence of droplet spacing of a water and glycerol solution on the morphology of the features printed by LIFT. We prove that it is indeed possible to print long and uniform continuous lines by controlling the overlap between adjacent droplets. We show how, depending on droplet spacing, several printed morphologies are generated, and we offer, in addition, a simple explanation of the observed behavior based on the jetting dynamics characteristic of the LIFT of liquids

Deposition and characterization of lines printed through laser-induced forward transfer

The possibility of printing two-dimensional micropatterns of biomolecule solutions is of great interest in many fields of research in biomedicine, from cell-growth and development studies to the investigation of the mechanisms of communication between cells. Although laser-induced forward transfer (LIFT) has been extensively used to print micrometric droplets of biological solutions, the fabrication of complex patterns depends on the feasibility of the technique to print micron-sized lines of aqueous solutions. In this study we investigate such a possibility through the analysis of the influence of droplet spacing of a water and glycerol solution on the morphology of the features printed by LIFT. We prove that it is indeed possible to print long and uniform continuous lines by controlling the overlap between adjacent droplets. We show how, depending on droplet spacing, several printed morphologies are generated, and we offer, in addition, a simple explanation of the observed behavior based on the jetting dynamics characteristic of the LIFT of liquids