Antonini S.,CNR Institute of Neuroscience |
Meucci S.,CNR Institute of Neuroscience |
Meucci S.,Italian Institute of Technology |
Jacchetti E.,CNR Institute of Neuroscience |
And 6 more authors.
Biomedical Materials (Bristol) | Year: 2015
Through the interaction with topographical features, endothelial cells tune their ability to populate target substrates, both in vivo and in vitro. Basal textures interfere with the establishment and maturation of focal adhesions (FAs) thus inducing specific cell-polarization patterns and regulating a plethora of cell activities that govern the overall endothelial function. In this study, we analyze the effect of topographical features on FAs in primary human endothelial cells. Reported data demonstrate a functional link between FA dynamics and cell polarization and spreading on structured substrates presenting variable lateral feature size. Our results reveal that gratings with 2 m lateral periodicity maximize contact guidance. The effect is linked to the dynamical state of FAs. We argue that these results are readily applicable to the rational design of active surfaces at the interface with the blood stream. © 2015 IOP Publishing Ltd.
Zurcher J.,IBM |
Chen X.,IBM |
Burg B.R.,IBM |
Zimmermann S.,IBM |
And 5 more authors.
IEEE-NANO 2015 - 15th International Conference on Nanotechnology | Year: 2015
A high thermally conductive underfill material is key for the efficient removal of heat generated by a 3-dimensional chip stack. Improved thermal properties are achieved by creating a percolating microparticle network within the composite underfill material. In this work, the directed assembly of nanoparticle necks formed by capillary bridging is investigated in order to improve the thermal transport in microparticle to microparticle contacts. The morphology of the formed necks using different alumina nanoparticle sizes and distributions, as well as a sol-gel binding system are characterized. High density and defect free nanoparticle necks were formed by using a mixture of small (28 - 43 nm) and large (200 - 300 nm) nanoparticles. The formation of such necks in the percolating alumina microparticle network increased the thermal conductivity of the underfill material from 1 W/mK without necks to 2.4 W/mK, a 2.4 × improvement in thermal conductivity. © 2015 IEEE.
Burg B.R.,Laboratory of Thermodynamics in Emerging Technologies |
Poulikakos D.,Laboratory of Thermodynamics in Emerging Technologies
Journal of Materials Research | Year: 2011
Device and sensor miniaturization has enabled extraordinary functionality and sensitivity enhancements over the last decades while considerably reducing fabrication costs and energy consumption. The traditional materials and process technologies used today will, however, ultimately run into fundamental limitations. Combining large-scale directed assembly methods with highsymmetry low-dimensional carbon nanomaterials is expected to contribute toward overcoming shortcomings of traditional process technologies and pave the way for commercially viable device nanofabrication. The purpose of this article is to review the guided dielectrophoretic integration of individual single-walled carbon nanotube (SWNT)- and graphene-based devices and sensors targeting continuous miniaturization. The review begins by introducing the electrokinetic framework of the dielectrophoretic deposition process, then discusses the importance of high-quality solutions, followed by the site- and type-selective integration of SWNTs and graphene with emphasis on experimental methods, and concludes with an overview of dielectrophoretically assembled devices and sensors to date. The field of dielectrophoretic device integration is filled with opportunities to research emerging materials, bottom-up integration processes, and promising applications. The ultimate goal is to fabricate ultra-small functional devices at high throughput and low costs, which require only minute operation power. © Materials Research Society 2011.
PubMed | Laboratory of Thermodynamics in Emerging Technologies
Type: Journal Article | Journal: Journal of neurosurgery | Year: 2013
The treatment of hydrocephalus requires insight into the intracranial dynamics in the patient. Resistance to CSF outflow (R0) is a clinically obtainable parameter of intracranial fluid dynamics that quantifies the apparent resistance to CSF absorption. It is used as a criterion for the selection of shunt candidates and serves as an indicator of shunt performance. The R0 is obtained clinically by performing 1 of 3 infusion tests: constant flow, constant pressure, or bolus infusion. Among these, the bolus infusion method has the shortest examination times and provides the shortest time of exposure of patients to artificially increased intracranial pressure (ICP) levels. However, for unknown reasons, the bolus infusion method systematically underestimates the R0. Here, the authors have tested and verified the hypothesis that this underestimation is due to lack of accounting for viscoelasticity of the craniospinal space in the calculation of the R0.The authors developed a phantom model of the human craniospinal space in order to reproduce in vivo pressure-volume (PV) relationships during infusion testing. The phantom model followed the Marmarou exponential PV equation and also included a viscoelastic response to volume changes. Parameters of intracranial fluid dynamics, such as the R0, could be controlled and set independently. In addition to the phantom model, the authors designed a computational framework for virtual infusion testing in which viscoelasticity can be turned on or off in a controlled manner. Constant flow, constant pressure, and bolus infusion tests were performed on the phantom model, as well as on the virtual computational platform, using standard clinical protocols. Values for the R0 were derived from each infusion test by using both a standard method based on the Marmarou PV equation and a novel method based on a system identification approach that takes into account viscoelastic behavior.Experiments with the phantom model confirmed clinical observations that both the constant flow and constant pressure infusion tests, but not the bolus infusion test, yield correct R0 values when they are determined with the standard method according to Marmarou. Equivalent results were obtained using the computational framework. When the novel system identification approach was used to determine the R0, all of the 3 infusion tests yielded correct values for the R0. CONCLUSIONS The authors investigations demonstrate that intracranial dynamics have a substantial viscoelastic component. When this viscoelastic component is taken into account in calculations, the R0, is no longer underestimated in the bolus infusion test.