Listening to MEMS: An acoustic vibrometer

new way to characterize vibrating MEMS devices is presented. Using an acoustic particle velocity sensor the coupled sound field is measured, which is a measure for the movement of the MEMS device. We present several possible applications of this measurement method. It can be used as a read-out system for a mass flow sensor, and for characterization of in- and out-of-plane movements of MEMS devices. The method is an interesting alternative to laser scanning vibrometry due to its small size and low complexity; furthermore, it allows the user to `listen' directly to MEMS devices

Single-mask thermal displacement sensor in MEMS

In this work we describe a one degree-of-freedom microelectromechanical thermal\ud displacement sensor integrated with an actuated stage. The system was fabricated in the device layer of a silicon-on-insulator wafer using a single-mask process. The sensor is based on the temperature dependent electrical resistivity of silicon and the heat transfer by conduction through a thin layer of air. On a measurement range of 50 μm and using a measurement bandwidth of 30 Hz, the 1-sigma noise corresponds to 3.47 nm. The power consumption of the sensor is 209 mW, almost completely independent of stage position. The drift of the sensor over a measurement period of 32 hours was 32 nm

A Musical instrument in MEMS

In this work we describe a MEMS instrument that resonates at audible frequencies, and with which music can be made. The sounds are generated by mechanical resonators and capacitive displacement sensors. Damping by air scales unfavourably for generating audible frequencies with small devices. Therefore a vacuum of 1.5 mbar is used to increase the quality factor and consequently the duration of the sounds to around 0.25 s. The instrument will be demonstrated during the MME 2010 conference opening, in a musical composition especially made for the occasion

Improved performance of large stroke comb-drive actuators by using a stepped finger shape

In this work we describe an electrostatic mass-balanced planar x/y-scanner, using an optimized comb finger shape, designed for parallel-probe storage applications. We show a new stepped comb finger shape design, that has superior force/displacement characteristics leading to a larger stroke at the same voltage and a larger available force compared to straight or tapered shapes.\u

A Mass-balanced through-wafer electrostatic x/y-scanner for probe data storage

In this work we describe the design, fabrication and testing of a mass-balanced planar x/y-scanner designed for parallel-probe storage applications (see Fig. 1a). We explore electrostatic actuation as an alternative to the electromagnetic actuation used in [1]. To increase the shock resistance, mass-balancing is used and the scanner is fabricated by deep reactive ion etching through a complete wafer. To move the scan table in both positive and negative x and y directions, four comb drives are used. The comb-drive fingers are tapered to increase the generated force without decreasing the minimum trench width

Thermally induced switching field distribution of a single CoPt dot in a large array

Magnetic dot arrays with perpendicular magnetic anisotropy were fabricated by patterning Co80Pt20-alloy continuous films by means of laser interference lithography. As commonly seen in large dot arrays, there is a large difference in the switching field between dots. Here we investigate the origin of this large switching field distribution, by using the anomalous Hall effect (AHE). The high sensitivity of the AHE permits us to measure the magnetic reversal of individual dots in an array of 80 dots with a diameter of 180 nm. By taking 1000 hysteresis loops we reveal the thermally induced switching field distribution SFDT of individual dots inside the array. The SFDT of the first and last switching dots were fitted to an Arrhenius model, and a clear difference in switching volume and magnetic anisotropy was observed between dots switching at low and high fields. \ud \u

A Musical instrument in MEMS

In this work we describe a MEMS instrument that resonates at audible frequencies, and with which music can be made. The sounds are generated by mechanical resonators and capacitive displacement sensors. Damping by air scales unfavourably for generating audible frequencies with small devices. Therefore a vacuum of 1.5 mbar is used to increase the quality factor and consequently the duration of the sounds to around 0.25 s. The instrument will be demonstrated during the MME 2010 conference opening, in a musical composition especially made for the occasion