Ruis bij de MicMec

Dit stuk gaat over ruis bij de MicMec. Uit het dagelijks leven weet je wel ongeveer wat ruis is, en bij het meten en bewerken van signalen speelt ruis een belangrijke rol, wat we ondervinden bij het onderzoek in de TST vakgroep

Integrated 3D Sound Intensity Sensor with Four-Wire Particle Velocity Sensors

A new symmetrical four-wire sensor configuration has resulted in a fully integrated sound intensity sensor with significant lower noise floor and smaller size than its predecessors. An integrated sound pressure sensor was further miniaturized by using a folded "back chamber" at both sides of the chip.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

A novel technique for measuring the reflection coefficient of sound absorbing materials

A new method to measure the acoustic behaviour of sound absorbing material in an impedance tube is presented. The method makes use of a novel particle velocity sensor, the microflown, and a microphone. The so-called p·u method is compared to three other methods of which the two microphone technique is well known. It is shown that the combination of a microphone and a microflown provides direct information on the acoustic impedance, the sound intensity and the sound energy density. The experimental results are compared to the results obtained with the conventional impedance tube measurements. To be able to repeat the measurements in a reliable way a well described test sample with a quarter-wave resonator is used. Furthermore it is shown that the viscothermal effects on the wave propagation are important, i.e. for the quarter-wave resonator and to a lesser extent for the impedance tube itself

Fully integrated three dimensional sound intensity sensor

For the first time, a complete 3-dimensional sound intensity sensor – consisting of 4 particle velocity sensors and a pressure microphone – has been integrated on a single chip, providing the possibility to do nearly point measurements of acoustic particle velocity, sound pressure, and therefore sound intensity. Principally the sensor consists of two distinct designs; a pressure sensor and particle velocity sensors. In this paper the design of the sensor, fabrication and measurement results are discussed and compared with theoretical results

Modeling and characterization of the sensitivity of a hot-wire particle velocity sensor

The sensitivity of an innovative acoustic sensor composed of four hot-wires is analyzed. An analytical model is presented that describes both the air flow and the temperature distribution in and around the probe. The presence of the chip surface in the vicinity of the wires influences the acoustic flow, while it also affects the temperature distribution. Both effects result into a specific angular dependence of the sensor sensitivity.\ud Acoustic measurements are compared with theory, showing good correspondence

Parallel optical readout of a cantilever array in dynamic mode

In this work we present parallel optical readout of a cantilever array which operates in dynamic mode using a standard optical beam deflection configuration containing only one laser-detector pair. We show accurate readout of the resonance frequency shift of an individual cantilever within an array by designing arrays where each cantilever has a different resonance frequency. The different resonance frequencies are created by giving each cantilever a different length and allow parallel readout of all cantilevers within the array. We show that even if the cantilevers are closely spaced each cantilever resonance frequency can be individually tracked without signs of cross-talk at current measurement precision (below 12 mHz). Interference of the laser light reflecting of each cantilever is observed when the amplitude of the cantilever is on the order of the wavelength of the laser light

Ultra-sharp soliton switching in a directional coupler

By a numerical investigation it is shown that a directional coupler, described by two linearly coupled non-linear Schro¨dinger equations, can be used to construct a soliton switch with an extremely narrow transition region

Nanotesla torque magnetometry using a microcantilever

We present a novel ultrasensitive magnetometry technique using a micromachined magnetic antilever that is brought in resonance. The induced magnetic moment generates a torque on the cantilever, thereby effectively stiffening the cantilever spring constant and changing its resonance frequency. Experiments are in good correspondence with the presented analytical model for this frequency shift, predicting the detection of nanotesla magnetic fields.\u

Capillarity effect in silicon based nanochannels

Using silicon based micromachining we have developed different techniques to create 1D and 2D confined nanochannels, with a characteristic diameter down to 5 nm. A short introduction to these techniques will be given. Capillary action in channels of this small size is a strong effect

Formation of liquid menisci in flexible nanochannels

This paper describes the elasto-capillary formation of menisci at the liquid-air interface in nanochannels that are covered with flexible capping membranes. The equilibrium between the capillary pressure in the fluid and the membrane bending results in a very peculiar shape of the meniscus. We present an analytical description of these meniscus hapes and show that the protrusion length of the meniscus along the channel is an accurate measure for the deflection of the nanochannels