496 research outputs found
Learning from Crickets: Artificial Hair-Sensor Array Developments
We have successfully developed biomimetic flowsensitive hair-sensor arrays taking inspiration from mechanosensory hairs of crickets. Our current generation of sensors achieves sub mm/s threshold air-flow sensitivity for single hairs operating in a bandwidth of a few hundred Hz and is the result of a few iterations in which the natural system (i.e. crickets filiform hair based mechano-sensors) have shown ample guidance to optimization. Important clues with respect to mechanical design, aerodynamics, viscous coupling effects and canopy based signal processing have been used during the course of our research. It is only by consideration of all these effects that we now may start thinking of systems performing a “flow-camera” function as found in nature in a variety of species
Micro coriolis flow sensor
Keywords: Coriolis flow sensor, surface channel technolog
Quasi-buckling of micromachined beams
Buckling of structures with imperfections, quasi-buckling (QB), is studied. At the bifurcation load, these structures show a smooth transition into one of the stable postbuckling equilibrium states, instead of the traditional sudden change in deflection characteristics. QB structures can show the classical snap-through buckling behaviour, i.e., a sudden change of postbuckling equilibrium state. The QB is described with a generalized temperature, Tg, representing the compression of the structure. Imperfections and distributed deflection loads are represented by a generalized pressure, pg. Experiments on micromachined beams, exposed to heating (Tg) and to a Lorentz force (pg), verify that the QB phenomena can efficiently transfer a longitudinal stress into a transversal deflection, with a scale-factor depending on both Tg and pg
Nano-flow thermal sensor applying dymamic w-2w sensing method
This article presents microchannel thermal flow sensors fabricated using standard micromachining technology. The sensors comprise of a SiXNY microchannel created by etching of a poly-Si sacrificial layer. The channels are released by KOH etching through inlets and outlets etched from the backside of the substrate. Liquid flow is measured by platinum resistors deposited on top of the microchannel, while the channel is thermally isolated from the substrate by a SiXNY membrane. Flow rates of DI water in the order of nlâ‹…min-1 have been measured using a dynamic sensing method applying heat waves
Fundamental study on a thin-film ae sensor for measurement of behavior of a multi-pad contact slider
To study the fundamental dynamic characteristics of a multi-pad slider for contact recording, we developed a thin-film piezoelectric acoustic emission array sensor on an Si-suspension with an array pattern similar to that of contact pads. Experiments showed that the sensitivity of the sensor is about 0. 11 V/N (slider thickness: 0.2 mm) and that each array sensor designed here is not influenced by the acoustic waves which occur due to contact with other contact pads, so the contact or non-contact condition of each pad can be measured
Buckled membranes for microstructures
Based on energy variation methods we calculated the deflection of membranes under the combined load of an external pressure and an internal lateral stress. A lateral load gives rise to buckling once a critical load is exceeded. The combination of transversal loads and lateral loads changes the properties of the membrane (and other structures) in the vicinity of the buckling load: The membrane deflects at all lateral loads and the critical load, above which two states are possible shifts. A result important for the design of microsystems, which are based on the buckling phenomenon, is the pressure required to switch the membrane from one state to the other. The theory is tested successfully with micromachined silicon/silicon-dioxide membrane
Interfacing of artificial hairs array for complex flow pattern recognition
In this paper we report on the latest developments in characterising and interfacing biomimetic flow-sensor array based on the flow sensitive mechano-sensors of crickets. Capacitive hair sensors have been fabricated using a surface micromachining technology and implemented to detect air flows. We have realized readout electronics to detect the movements capacitively using electrodes integrated on the membrane. A charge amplifier, which produces an output voltage representing the capacitance variation of the selected sensor, is used to pick up the signal. An array of hair sensors is implemented for better and more representative flow signals compared to single sensor measurement. Different schemes for measuring individual sensors in arrays independently are discussed. Frequency Division Multiplexing is found to be efficient for this purpose individual element measurement.\ud
Key Words: Artificial hairs, capacitive readout, FD
- …