Strain-engineered manufacturing of freeform carbon nanotube microstructures.

The skins of many plants and animals have intricate microscale surface features that give rise to properties such as directed water repellency and adhesion, camouflage, and resistance to fouling. However, engineered mimicry of these designs has been restrained by the limited capabilities of top-down fabrication processes. Here we demonstrate a new technique for scalable manufacturing of freeform microstructures via strain-engineered growth of aligned carbon nanotubes (CNTs). Offset patterning of the CNT growth catalyst is used to locally modulate the CNT growth rate. This causes the CNTs to collectively bend during growth, with exceptional uniformity over large areas. The final shape of the curved CNT microstructures can be designed via finite element modeling, and compound catalyst shapes produce microstructures with multidirectional curvature and unusual self-organized patterns. Conformal coating of the CNTs enables tuning of the mechanical properties independently from the microstructure geometry, representing a versatile principle for design and manufacturing of complex microstructured surfaces.This is the author accepted manuscript. The final published version can be found in Nature Communications here: http://www.nature.com/ncomms/2014/140729/ncomms5512/full/ncomms5512.html. This paper will be under embargo until 29/1/15

Ruddlesden Popper 2D perovskites as Li-ion battery electrodes

The electrochemical performance of 2-dimensional hybrid perovskite electrodes for Li-ion batteries are investigated using a high-molarity electrolyte. The effect of changing the halide content and layering structure is systematically explored.</p

Predictive Synthesis of Freeform Carbon Nanotube Microarchitectures by Strain-Engineered Chemical Vapor Deposition.

High-throughput fabrication of microstructured surfaces with multi-directional, re-entrant, or otherwise curved features is becoming increasingly important for applications such as phase change heat transfer, adhesive gripping, and control of electromagnetic waves. Toward this goal, curved microstructures of aligned carbon nanotubes (CNTs) can be fabricated by engineered variation of the CNT growth rate within each microstructure, for example by patterning of the CNT growth catalyst partially upon a layer which retards the CNT growth rate. This study develops a finite-element simulation framework for predictive synthesis of complex CNT microarchitectures by this strain-engineered growth process. The simulation is informed by parametric measurements of the CNT growth kinetics, and the anisotropic mechanical properties of the CNTs, and predicts the shape of CNT microstructures with impressive fidelity. Moreover, the simulation calculates the internal stress distribution that results from extreme deformation of the CNT structures during growth, and shows that delamination of the interface between the differentially growing segments occurs at a critical shear stress. Guided by these insights, experiments are performed to study the time- and geometry-depended stress development, and it is demonstrated that corrugating the interface between the segments of each microstructure mitigates the interface failure. This study presents a methodology for 3D microstructure design based on "pixels" that prescribe directionality to the resulting microstructure, and show that this framework enables the predictive synthesis of more complex architectures including twisted and truss-like forms.Air Force Office of Scientific Research Young Investigator Program (FA9550-11-1-0089), MIT Department of Mechanical Engineering, National Science Foundation (CMMI-1463344), National Institutes of Health (1R21HL114011-01A1), European Research Council (starting grant 337739-HIENA), Marie Curie (CIG Grant 618250-CANA

Comparison of selective culture media for the isolation of Taxon K species belonging to the Burkholderia cepacia complex

Objetivo: Dentro del complejo Burkholderia cepacia (cBc), el Taxón K, integrado por B. contaminans y B. lata, es frecuentemente aislado de muestras clínicas e industriales. Los métodos para aislar bacterias del cBc están consensuados en el ámbito clínico pero no para muestras de origen industrial y tampoco hay información documentada sobre la capacidad de recuperación de los medios de cultivo frente a especies del Taxón K. Dada la importancia del uso correcto de medios selectivos para la recuperación de microorganismos, el objetivo de este trabajo fue comparar el agar Trypan Blue-Tetraciclina (TB-T), el agar selectivo para Burkholderia cepacia (BCSA) y el BCSA comercial modificado (BCSAm) en el aislamiento de cepas del Taxón K. Métodos: empleamos el método ecométrico utilizado en el control de calidad de medios de cultivo. Analizamos criterios de productividad, selectividad y especificidad frente a cepas de referencia del cBc, aislamientos clínicos e industriales del Taxón K y cepas de otras especies. Resultados: no se observaron diferencias de productividad y selectividad entre los medios BCSA. Con ambos se obtuvo adecuada productividad y selectividad parcial por permitir el crecimiento de especies taxonómicamente cercanas al cBc. El medio TB-T presentó menor productividad (especialmente con B. contaminans) y menor selectividad. Por otra parte, no se observaron diferencias atribuibles al origen clínico o industrial de los aislamientos. Conclusión: los resultados permiten sugerir al BCSA o BCSAm como los medios selectivos de elección para el aislamiento del Taxón K, tanto en muestras de origen clínico como industrial.Objective: Within the Burkholderia cepacia complex (Bcc), the so called Taxon K, integrated by B. contaminans and B. lata, is frequently isolated from clinical and industrial samples. There is consensus in the use of culture media for the isolation of Bcc from clinical origin but not for industrial samples. By the other side there is no documented information about the performance of culture media recovering Taxon K species. Regarding the importance of the proper use of selective media in the recovery of microorganisms from clinical and industrial samples, the objective of this work was to compare Trypan Blue-Tetracycline agar (TB-T), Burkholderia cepacia selective agar (BCSA) and commercial modified Burkholderia cepacia selective agar (BCSAm) in the isolation of Taxon K strains. Methods: we employed the ecometric method for culture media quality control. Productivity, selectivity and specificity criteria were analyzed by testing Bcc reference strains, clinical and industrial Taxon K isolates and non Bcc strains. Results: no differences in terms of productivity and selectivity were observed between BCSA and BCSAm. Both medium, displayed adequate productivity and partial selectivity since the growth of non Bcc isolates was observed. Productivity (especially with B. contaminans isolates) and selectivity in TB-T was lower than BCSA medium. No differences were observed related to the clinical or industrial origin of isolates. Conclusion: results allow us to suggest BCSA or BCSAm selective media for the isolation of Taxon K strains in clinical or industrial samples.Los fondos para la realización del presente trabajo fueron aportados por la cuenta “Métodos Microbianos” administrada bajo el ámbito de la Facultad de Farmacia y Bioquímica de la Universidad de Buenos Aires

Elastic Inflatable Actuators for Soft Robotic Applications

The 20th century’s robotic systems have been made out of stiff materials and much of the developments in the field have pursued ever more accurate and dynamic robots which thrive in industrial automation settings and will probably continue to do so for many decades to come. However, the 21st century’s robotic legacy may very well become that of soft robots. This emerging domain is characterized by continuous soft structures that simultaneously fulfil the role of robotic link and robotic actuator, where prime focus is on design and fabrication of the robotic hardware instead of software control to achieve a desired operation. These robots are anticipated to take a prominent role in delicate tasks where classic robots fail, such as in minimally invasive surgery, active prosthetics and automation tasks involving delicate irregular objects. Central to the development of these robots is the fabrication of soft actuators to generate movement. This paper reviews a particularly attractive type of soft actuators that are driven by pressurized fluids. These actuators have recently gained substantial traction on the one hand due to the technology push from better simulation tools and new manufacturing technologies including soft-lithography and additive manufacturing, and on the other hand by a market pull from the applications listed above. This paper provides an overview of the different advanced soft actuator configurations, their design, fabrication and applications.This research is supported by the Fund for Scientific Research-Flanders (FWO), and the European Research Council (ERC starting grant HIENA)

Quantification and role of innate lymphoid cell subsets in Chronic Obstructive Pulmonary Disease

Objectives Innate lymphoid cells (ILCs) secrete cytokines, such as IFN-γ, IL-13 and IL-17, which are linked to chronic obstructive pulmonary disease (COPD). Here, we investigated the role of pulmonary ILCs in COPD pathogenesis. Methods Lung ILC subsets in COPD and control subjects were quantified using flow cytometry and associated with clinical parameters. Tissue localisation of ILC and T-cell subsets was determined by immunohistochemistry. Mice were exposed to air or cigarette smoke (CS) for 1, 4 or 24 weeks to investigate whether pulmonary ILC numbers and activation are altered and whether they contribute to CS-induced innate inflammatory responses. Results Quantification of lung ILC subsets demonstrated that ILC1 frequency in the total ILC population was elevated in COPD and was associated with smoking and severity of respiratory symptoms (COPD Assessment Test [CAT] score). All three ILC subsets localised near lymphoid aggregates in COPD. In the COPD mouse model, CS exposure in C57BL/6J mice increased ILC numbers at all time points, with relative increases in ILC1 in bronchoalveolar lavage (BAL) fluid. Importantly, CS exposure induced increases in neutrophils, monocytes and dendritic cells that remained elevated in Rag2/Il2rg-deficient mice that lack adaptive immune cells and ILCs. However, CS-induced CXCL1, IL-6, TNF-α and IFN-γ levels were reduced by ILC deficiency. Conclusion The ILC1 subset is increased in COPD patients and correlates with smoking and severity of respiratory symptoms. ILCs also increase upon CS exposure in C57BL/6J mice. In the absence of adaptive immunity, ILCs contribute to CS-induced pro-inflammatory mediator release, but are redundant in CS-induced innate inflammation

New type of microengine using internal combustion of hydrogen and oxygen

Microsystems become part of everyday life but their application is restricted by lack of strong and fast motors (actuators) converting energy into motion. For example, widespread internal combustion engines cannot be scaled down because combustion reactions are quenched in a small space. Here we present an actuator with the dimensions 100x100x5 um^3 that is using internal combustion of hydrogen and oxygen as part of its working cycle. Water electrolysis driven by short voltage pulses creates an extra pressure of 0.5-4 bar for a time of 100-400 us in a chamber closed by a flexible membrane. When the pulses are switched off this pressure is released even faster allowing production of mechanical work in short cycles. We provide arguments that this unexpectedly fast pressure decrease is due to spontaneous combustion of the gases in the chamber. This actuator is the first step to truly microscopic combustion engines.Comment: Paper and Supplementary Information (to appear in Scientific Reports