Fast on-wafer electrical, mechanical, and electromechanical characterization of piezoresistive cantilever force sensors

Validation of a technological process requires an intensive characterization of the performance of the resulting devices, circuits, or systems. The technology for the fabrication of micro and nanoelectromechanical systems (MEMS and NEMS) is evolving rapidly, with new kind of device concepts for applications like sensing or harvesting are being proposed and demonstrated. However, the characterization tools and methods for these new devices are still not fully developed. Here, we present an on-wafer, highly precise, and rapid characterization method to measure the mechanical, electrical, and electromechanical properties of piezoresistive cantilevers. The setup is based on a combination of probe-card and atomic force microscopy technology, it allows accessing many devices across a wafer and it can be applied to a broad range of MEMS and NEMS. Using this setup we have characterized the performance of multiple submicron thick piezoresistive cantilever force sensors. For the best design we have obtained a force sensitivity ℜ_F = 158μV/nN, a noise of 5.8 μV (1 Hz–1 kHz) and a minimum detectable force of 37 pN with a relative standard deviation of σ_r ≈ 8%. This small value of σr, together with a high fabrication yield >95%, validates our fabrication technology. These devices are intended to be used as bio-molecular detectors for the measurement of intermolecular forces between ligand and receptor molecule pairs

Interactions between sub-10 nm iron and cerium oxide nanoparticles and 3T3 fibroblasts : the role of the coating and aggregation state

Recent nanotoxicity studies revealed that the physico-chemical characteristics of engineered nanomaterials play an important role in the interactions with living cells. Here, we report on the toxicity and uptake of the cerium and iron oxide sub-10 nm nanoparticles by NIH/3T3 mouse fibroblasts. Coating strategies include low-molecular weight ligands (citric acid) and polymers (poly(acrylic acid), MW = 2000 g mol-1). Electrostatically adsorbed on the surfaces, the organic moieties provide a negatively charged coating in physiological conditions. We find that most particles were biocompatible, as exposed cells remained 100% viable relative to controls. Only the bare and the citrate-coated nanoceria exhibit a slight decrease of the mitochondrial activity for cerium concentrations above 5 mM (equivalent to 0.8 g L-1). We also observe that the citrate-coated particles are internalized by the cells in large amounts, typically 250 pg per cell after a 24 h incubation for iron oxide. In contrast, the polymer-coated particles are taken up at much lower rates (< 30 pg per cell). The strong uptake shown by the citrate-coated particles is related to the destabilization of the dispersions in the cell culture medium and their sedimentation down to the cell membranes. In conclusion, we show that the uptake of nanomaterials by living cells depends on the coating of the particles and on its ability to preserve the colloidal nature of the dispersions.Comment: 9 figures, 2 table

User-generated online health content: A survey of internet users in the United Kingdom

This is the final version. Available on open access from JMIR Publications via the DOI in this recordThe production of health information has begun to shift from commercial organizations to health care users themselves. People increasingly go online to share their own health and illness experiences and to access information others have posted, but this behavior has not been investigated at a population level in the United Kingdom. Objective: This study aims to explore access and production of user-generated health content among UK Internet users and to investigate relationships between frequency of use and other variables. Methods: We undertook an online survey of 1000 UK Internet users. Descriptive and multivariate statistical analyses were used to interpret the data. Results: Nearly one-quarter of respondents (23.7%, 237/1000) reported accessing and sharing user-generated health content online, whereas more than 20% (22.2%, 222/1000) were unaware that it was possible to do this. Respondents could be divided into 3 groups based on frequency of use: rare users (78.7%, 612/778) who accessed and shared content less than weekly, users (13.9%, 108/778) who did so weekly, and superusers (7.5%, 58/778) who did so on a daily basis. Superusers were more likely to be male (P<.001) and to be employed (P<.001), but there were no differences between the groups with respect to educational level (P=.99) or health status (P=.63). They were more likely to use the Internet for varied purposes such as banking and shopping (P<.001). Conclusions: Although this study found reasonably widespread access of user-generated online health content, only a minority of respondents reported doing so frequently. As this type of content proliferates, superusers are likely to shape the health information that others access. Further research should assess the effect of user-generated online content on health outcomes and use of health services by Internet users. © Martin Duracinsky, Christophe Lalanne, Cécile Goujard, Susan Herrmann, Christian Cheung-Lung, Jean-Paul Brosseau, Yannick Schwartz, Olivier Chassany.Institute for Prospective Technological Studies (IPTS)European Commission’s Joint Research Centre (JRC)European Commission Directorate General for Communications Networks, Content and Technology (DG Connect

The Golden Channel at a Neutrino Factory revisited: improved sensitivities from a Magnetised Iron Neutrino Detector

This paper describes the performance and sensitivity to neutrino mixing parameters of a Magnetised Iron Neutrino Detector (MIND) at a Neutrino Factory with a neutrino beam created from the decay of 10 GeV muons. Specifically, it is concerned with the ability of such a detector to detect muons of the opposite sign to those stored (wrong-sign muons) while suppressing contamination of the signal from the interactions of other neutrino species in the beam. A new more realistic simulation and analysis, which improves the efficiency of this detector at low energies, has been developed using the GENIE neutrino event generator and the GEANT4 simulation toolkit. Low energy neutrino events down to 1 GeV were selected, while reducing backgrounds to the $10^{-4}$ level. Signal efficiency plateaus of ~60% for $\nu_\mu$ and ~70% for $\bar{\nu}_\mu$ events were achieved starting at ~5 GeV. Contamination from the $\nu_\mu\rightarrow \nu_\tau$ oscillation channel was studied for the first time and was found to be at the level between 1% and 4%. Full response matrices are supplied for all the signal and background channels from 1 GeV to 10 GeV. The sensitivity of an experiment involving a MIND detector of 100 ktonnes at 2000 km from the Neutrino Factory is calculated for the case of $\sin^2 2\theta_{13}\sim 10^{-1}$. For this value of $\theta_{13}$, the accuracy in the measurement of the CP violating phase is estimated to be $\Delta \delta_{CP}\sim 3^\circ - 5^\circ$, depending on the value of $\delta_{CP}$, the CP coverage at $5\sigma$ is 85% and the mass hierarchy would be determined with better than $5\sigma$ level for all values of $\delta_{CP}$

Toroidal magnetized iron neutrino detector for a neutrino factory

A neutrino factory has unparalleled physics reach for the discovery and measurement of CP violation in the neutrino sector. A far detector for a neutrino factory must have good charge identification with excellent background rejection and a large mass. An elegant solution is to construct a magnetized iron neutrino detector (MIND) along the lines of MINOS, where iron plates provide a toroidal magnetic field and scintillator planes provide 3D space points. In this paper, the current status of a simulation of a toroidal MIND for a neutrino factory is discussed in light of the recent measurements of large θ13. The response and performance using the 10 GeV neutrino factory configuration are presented. It is shown that this setup has equivalent δCP reach to a MIND with a dipole field and is sensitive to the discovery of CP violation over 85% of the values of δCP