179 research outputs found
Fiber-top atomic force microscope
We present the implementation of an atomic force microscope (AFM) based on fiber-top design. Our results demonstrate that the performances of fiber-top AFMs in contact mode are comparable to those of similar commercially available instruments. Our device thus represents an interesting\ud
alternative to existing AFMs, particularly for applications outside specialized research laboratories, where a compact, user-friendly, and versatile tool might often be preferred
Capillary origami of micro-machined micro-objects: Bi-layer conductive hinges
Recently, we demonstrated controllable 3D self-folding by means of capillary
forces of silicon-nitride micro-objects made of rigid plates connected to each
other by flexible hinges [1]. In this paper, we introduce platinum electrodes
running from the substrate to the plates over these bendable hinges. The
fabrication yield is as high as (77 +/- 2) % for hinges with a length less than
75 {\mu}m. The yield reduces to (18 +/- 2) % when the length increases above
100 {\mu}m. Most of the failures in conductivity are due to degradation of the
platinum/chromium layer stack during the final plasma cleaning step. The
bi-layer hinges survive the capillary folding process, even for extremely small
bending radii of 5 {\mu}m, nor does the bending have any impact on the
conductivity. Stress in the different layers deforms the hinges, which does not
affect the conductivity. Once assembled, the conductive hinges can withstand a
current density of (1.6 +/- 0.4) A/cm . This introduction of
conductive electrodes to elastocapillary self-folded silicon-based
micro-objects extends the range of their possible applications by allowing an
electronic functionality of the folded parts.Comment: Currently on a peer review process. 13 page
Elastocapillary folding using stop-programmable hinges fabricated by 3D micro-machining
We show elasto-capillary folding of silicon nitride objects with accurate
folding angles between flaps of 70.60.1{\deg} and demonstrate the
feasibility of such accurate micro-assembly with a final folding angle of
90{\deg}. The folding angle is defined by stop-programmable hinges that are
fabricated starting from silicon molds employing accurate three-dimensional
corner lithography. This nano-patterning method exploits the conformal
deposition and the subsequent timed isotropic etching of a thin film in a 3D
shaped silicon template. The technique leaves a residue of the thin film in
sharp concave corners which can be used as an inversion mask in subsequent
steps. Hinges designed to stop the folding at 70.6{\deg} were fabricated
batchwise by machining the V-grooves obtained by KOH etching in (110) silicon
wafers; 90{\deg} stop-programmable hinges were obtained starting from silicon
molds obtained by dry etching on (100) wafers. The presented technique is
applicable to any folding angle and opens a new route towards creating
structures with increased complexity, which will ultimately lead to a novel
method for device fabrication.Comment: Submitted to a peer reviewed journa
Fabrication of thick silicon nitride blocks for integration of rf devices
A fabrication process for the creation of thick (tens of micrometres) silicon nitride blocks embedded in silicon wafers has been developed This new technology allows the use of silicon nitride as dielectric material for radio frequency (RF) circuits on standard CMOS-grade silicon wafers. Measurement results show that a performance similar to that of dedicated glass substrates can be reache
Design, fabrication and characterization of a suspended plate mechano-optical modulator
A mechano-optical modulator is presented based on the Integrated Optical Nano-Mechanical (IONM) effect. It consists of a light-weight, rigid silicon-nitride suspended plate structure with strengthening ridges and bi-directional electrostatic actuation to maximize switching speed. The mechanical structure and optical waveguide are realized on separate chips and then assembled together resulting in hybrid integration. The latter is made possible by using a self-alignment technique which results in a misalignment error of at most 2 μm
Mechanical tuning of optical race-track ring resonators
This paper presents the fabrication and mechanical characterization of electrostatically actuated micro bimorphs integrated with race-track ring resonators, for optical tuning applications. The bimorphs, having an upward deflection in the off-state, are integrated by surface micromachining techniques with race-track ring resonators fabricated on Silicon On Insulator (SOI) wafers. Using electrostatic actuation, these bimorphs are pulled into the evanescent field of the ring resonator thereby modulating the propagation properties. Pull-in voltages of the bimorphs have been measured statically and the effect of electrostatic spring softening (ESS) on the resonance frequency has been measured dynamically. The resonance wavelength of the optical ring resonator could be tuned by 50 pm by applying an 8.5 V DC voltage to a 40 μm long bimorph, bringing it into close proximity of the ring resonator waveguide. To the best of our knowledge, this is the first experimental demonstration of tuning of race track ring resonators by integrated, electrostatically actuated bimorphs.\ud
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The Price of Land and the Process of Expropriation
This paper applies a game theoretic model to situations in which the Dutch government expropriates land from some farmers in order to create a new public project. The model is a version of a finite period bargaining model with asymmetric information and one-sided offers. It is shown that the model can explain some casual observations as the fact that usually, but not always, the government and the farmers settle by agreement
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