Pull-in actuation in hybrid micro-machined contactless suspension

This paper presents a result of study of the pull-in phenomenon in the hybrid micro-machined contactless suspension (µ-HCS), combining inductive suspension and electrostatic actuation, reported at PowerMEMS 2015 [1]. Assuming the quasi-static behavior of a levitated proof mass, a non-linear analytical model describing the pull-in actuation along the vertical direction is developed. The developed model allows us to predict the static pull-in parameters of the suspension and to show a dependence of these parameters on suspension design. It is shown that the pull-in displacement can be larger by almost a factor of two than one occurring in a spring-mass system with constant stiffness (classic pull-in). The model is verified by using numerical estimations as well as experimental data and agrees well with measurements and calculations

Energy-aware 3D micro-machined inductive suspensions with polymer magnetic composite core

This paper addresses the issue of Joule heating in micromachined inductive suspensions (MIS) and reports a significant decrease of the operating temperature by using a polymer magnetic composite (PMC) core. The PMC material has a high resistivity, thus inhibiting the formation of eddy currents, and a high permeability, thus guiding the magnetic field more efficiently within the MIS structure. We experimentally study the distribution of the PMC material inside the MIS structure and evaluate the effect of the core from the dependence of the levitation height on the excitation current. The experiments carried on in ambient room temperature demonstrate that the temperature inside the micromachined inductive suspension is reduced to 58°C, which is a record-low temperature compared to other MIS structures reported before

Hybrid electromagnetic and electrostatic micromachined suspension with adjustable dynamics

This paper introduces a novel design for a hybrid micromachined contactless suspension, whose operation is based on combining electromagnetic inductive and electrostatic actuation. Wirebonded microcoils provide the electromagnetic inductive actuation, while electrodes patterned on a Si wafer provide electrostatic control. The coil structure and the electrode structure are independently designed and fabricated, and are finally assembled into one device by flip-chip bonding. We demonstrate vertical linear positioning of an aluminium disk-shaped proof mass in a range from 30 to 200 μm based on the coil structure. The electrode structure is employed to dynamically adjust the stiffness components during the operation of the suspension, to control the tilting in a range from ±1° to ±4°, as well as to control the oscillation about the vertical axis with a displacement of 37° at about 1.5 Hz frequency

Heteronuclear micro-helmholtz coil facilitates μm-range spatial and sub-Hz spectral resolution NMR of nL-volume samples on customisable microfluidic chips

We present a completely revised generation of a modular micro-NMR detector, featuring an active sample volume of ∗ 100 nL, and an improvement of 87% in probe efficiency. The detector is capable of rapidly screening different samples using exchangeable, applicationspecific, MEMS-fabricated, microfluidic sample containers. In contrast to our previous design, the sample holder chips can be simply sealed with adhesive tape, with excellent adhesion due to the smooth surfaces surrounding the fluidic ports, and so withstand pressures of ∗2.5 bar, while simultaneously enabling high spectral resolution up to 0.62 Hz for H2 O, due to its optimised geometry. We have additionally reworked the coil design and fabrication processes, replacing liquid photoresists by dry film stock, whose final thickness does not depend on accurate volume dispensing or precise levelling during curing. We further introduced mechanical alignment structures to avoid time-intensive optical alignment of the chip stacks during assembly, while we exchanged the laser-cut, PMMA spacers by diced glass spacers, which are not susceptible to melting during cutting. Doing so led to an overall simplification of the entire fabrication chain, while simultaneously increasing the yield, due to an improved uniformity of thickness of the individual layers, and in addition, due to more accurate vertical positioning of the wirebonded coils, now delimited by a post base plateau. We demonstrate the capability of the design by acquiring a1 H spectrum of ∗ \11 nmol sucrose dissolved in D2 O, where we achieved a linewidth of 1.25 Hz for the TSP reference peak. Chemical shift imaging experiments were further recorded from voxel volumes of only ∗ 1.5nL, which corresponded to amounts of just 1.5 nmol per voxel for a 1 M concentration. To extend the micro-detector to other nuclei of interest, we have implemented a trap circuit, enabling heteronuclear spectroscopy, demonstrated by two 1H/13 C 2D HSQC experiments. © 2016 Spengler et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Light-current characterization of dual-wavelength VCSELs

The purpose of this paper is to present a detailed characterization of a dual-wavelength VCSEL - the BiVCSEL. This device consists of two active optical cavities, which share a coupling mirror and can be independently electrically pumped. We present the output powers for the two emitted wavelengths (short - lambda(S), long - lambda(L)) versus the currents in the two cavities (I-TOP, I-BOT). These (lambda(S), lambda(L))-(I-TOP, I-BOT) maps identify the different regimes of operation of the BiVCSEL: emission at only one wavelength (either short or long) and dual-wavelength emission, each domain being delimitated by the threshold curves. These curves are passing through a single point, which identify the dual-emission threshold (I-TOP(th), I-BOT(th)). The apparition of a parasitic lasing mode due to the oxide apertures will be also presented as well as the competition between this mode and the designed lasing modes of the structure