Highly sensitive micro coriolis mass flow sensor

We have realized a micromachined micro Coriolis mass flow sensor consisting of a silicon nitride resonant tube of 40 ?m diameter and 1.2 μm wall thickness. Actuation of the sensor in resonance mode is achieved by Lorentz forces. First measurements with both gas and liquid flow have demonstrated a resolution in the order of 10 milligram per hour. The sensor can simultaneously be used as a density sensor

MEMS based hair flow-sensors as model systems for acoustic perception studies

Arrays of MEMS fabricated flow sensors inspired by the acoustic flow-sensitive hairs found on the cerci of crickets, have been designed, fabricated and characterized. The hairs consist of up to 1 mm long SU-8 structures mounted on suspended membranes with normal translational and rotational degrees of freedom. Electrodes on the membrane and on the substrate form variable capacitors allowing for capacitive read-out. Capacitance versus voltage, frequency dependency and directional sensitivity measurements have been successfully carried out on fabricated sensor arrays, showing the viability of the concept. The sensors form a model-system allowing for investigations on sensory acoustics by their arrayed nature, their adaptivity via electrostatic interaction (frequency tuning and parametric amplifica- tion) and their susceptibility to noise (stochastic resonance

A versatile technology platform for microfluidic handling systems, part I:fabrication and functionalization

Many microfluidic devices are made using specialized fabrication processes, limiting the ability to integrate those devices on the same chip. In this paper, a versatile technology platform is presented that allows for integration of many different devices. It provides a method to design channels in a wide range of sizes and shapes with different functionalization options in close proximity to the fluid in the channels. The latter includes release of the channels for thermal isolation or mechanical movement and metal or piezoelectric layers for actuation and read-out. The channel walls are made using silicon-rich silicon nitride to provide durable, strong, chemically inert and thermally stable channels directly below the substrate surface

Towards a Casimir force measurement between micromachined parallel plate structures

Ever since its prediction, experimental investigation of the Casimir force has been of great scientific interest. Many research groups have successfully attempted quantifying the force with different device geometries; however, measurement of the Casimir force between parallel plates with sub-micron separation distance is still a challenging task, since it becomes extremely difficult to maintain sufficient parallelism between the plates. The Casimir force can significantly influence the operation of micro devices and to realize reliable and reproducible devices it is necessary to understand and experimentally verify the influence of the Casimir force at sub-micron scale. In this paper, we present the design principle, fabrication and characterization of micromachined parallel plate structures that could allow the measurement of the Casimir force with tunable separation distance in the range of 100 to 1000 nm. Initially, a gold coated parallel plate structure is explored to measure the Casimir force, but also other material combinations could be investigated. Using gold-silicon eutectic bonding, a reliable approach to bond chips with integrated suspended plates together with a well-defined separation distance in the order of 1–2 μm is developed

DecidArch: Playing Cards as Software Architects

Teaching software architecture is a challenge because of the difficulty to expose students to actual meaningful design situations. Games can provide a useful illustration of the design decision making process, and teach students the power of team interaction for making sound decisions. We introduce a game –DecidArch– developed to achieve three learning objectives: _x0001_1) create awareness about the rationale involved in design decision making, _x0002_2) enable appreciation of the reasoning behind candidate design decisions proposed by others, and _x0003_3) create awareness about interdependencies between design decisions. The game has been played by _x0002__x0002_ groups with a total of _x0008__x0003_ players, all of them students of the VU software architecture course. We present some of the lessons learned, both from our observation and through participant survey. We conclude that the game well supports our three learning objectives, and we identify several improvement points for future game editions

Selective SiO2 etching in three dimensional structures using parylene-C as mask

This abstract describes an application of an easy and straightforward method for selective SiO2 etching in three dimensional structures, which is developed by our group. The application in this abstract is the protection of the buried-oxide (BOX) layer of a silicon-on-insulator (SOI) wafer against SiO2 hard mask stripping in BHF after deep reactive ion etching (DRIE) in the device layer, where the BOX layer serves as etch stop. It enables further processing like refilling of trenches and other structures with preservation of the BOX layer, which can serve as sacrificial layer or electrical isolation. The BOX layer protection is done with parylene-C. This is a poly(monochloro-p-xylylene) polymer, which is traditionally used to coat implantable devices, used as protective packaging material in (chemical) sensors, or as actual shapeable material in devices. The presented method adds mask material for selective SiO2 etching to the list

Ambient temperature-gradient compensated low-drift thermopile flow sensor

A highly-sensitive thermal flow sensor for liquid flow with nl-min-1 resolution has been realised. The sensor consists of freely-suspended silicon-rich silicon-nitride microchannels with integrated Al heater resistors and Al/poly-Si++ thermopiles. The influence of drift in the thin-film metal resistors is effectively eliminated by using thermopiles combined with an adequate measurement method, where the power in the heater resistors is controlled, e.g. constant-power calorimetric method or temperature balancing method. The special meandering layout of the microchannels and the placement of thermopile junctions increases sensitivity by summing the thermopile voltages due to convection by fluid flow, whereas the influence of ambient temperature gradients is compensated for