Excitation and detection of vibrations of micromechanical structures using a dielectric thin film

A new technique is introduced for both the excitation and the detection of vibrations of micromechanical structures. This makes use of a dielectric thin film, sandwiched between lower and upper electrodes, on top of the vibrating structure. The excitation is based on electrostatic forces between the charged electrodes, causing deformation of the dielectric film and bending of the multilayer structure. The detection of the vibration is capacitive, based on the fluctuation of the capacitance due to the deformation of the dielectric film. Experimental results for a stoichiometric silicon nitride dielectric film on top of a silicon cantilever agree well with predicted values. The yield of the electrostatic excitation as well as of the capacitive detection are satisfactory

MEMS Technology for Space Applications

Micro-technology enables the manufacturing of all kinds of components for miniature systems or micro-systems, such as sensors, pumps, valves, and channels. The integration of these components into a micro-electro-mechanical system (MEMS) drastically decreases the total system volume and mass. These properties, combined with the increasing need for monitoring and control of small flows in (bio)chemical experiments, makes MEMS attractive for space applications. The level of integration and applied technology depends on the product demands and the market. The ultimate integration is process integration, which results in a one-chip system. An example of process integration is a dosing system of pump, flow sensor, micromixer, and hybrid feedback electronics to regulate the flow. However, for many applications, a hybrid integration of components is sufficient and offers the advantages of design flexibility and even the exchange of components in the case of a modular set up. Currently, we are working on hybrid integration of all kinds of sensors (physical and chemical) and flow system modules towards a modular system; the micro total analysis system (micro TAS). The substrate contains electrical connections as in a printed circuit board (PCB) as well as fluid channels for a circuit channel board (CCB) which, when integrated, form a mixed circuit board (MCB)

Spontaneous mechanical oscillation of a DC driven single crystal

There is a large interest to decrease the size of mechanical oscillators since this can lead to miniaturization of timing and frequency referencing devices, but also because of the potential of small mechanical oscillators as extremely sensitive sensors. Here we show that a single crystal silicon resonator structure spontaneously starts to oscillate when driven by a constant direct current (DC). The mechanical oscillation is sustained by an electrothermomechanical feedback effect in a nanobeam, which operates as a mechanical displacement amplifier. The displacement of the resonator mass is amplified, because it modulates the resistive heating power in the nanobeam via the piezoresistive effect, which results in a temperature variation that causes a thermal expansion feedback-force from the nanobeam on the resonator mass. This self-amplification effect can occur in almost any conducting material, but is particularly effective when the current density and mechanical stress are concentrated in beams of nano-scale dimensions

Hybrid integrated semiconductor lasers with silicon nitride feedback circuits

Hybrid integrated semiconductor laser sources offering extremely narrow spectral linewidth as well as compatibility for embedding into integrated photonic circuits are of high importance for a wide range of applications. We present an overview on our recently developed hybrid-integrated diode lasers with feedback from low-loss silicon nitride (Si3N4 in SiO2) circuits, to provide sub-100-Hz-level intrinsic linewidths, up to 120 nm spectral coverage around 1.55 um wavelength, and an output power above 100 mW. We show dual-wavelength operation, dual-gain operation, laser frequency comb generation, and present work towards realizing a visible-light hybrid integrated diode laser.Comment: 25 pages, 16 figure

Thermal fragmentation of a 1,5,2-oxathiazole 5-oxide system via two parallel pathways: interception of a vinyl nitrene and of a sulphene

1,5,2-Oxathiazole -5-oxide, fragmentatio