Three dimensional silicon triple-hot-wire anemometer based on polyimide joints

Micro-electro-mechanical system (MEMS) devices integrate various mechanical elements, sensors, actuators, and electronics on a single silicon substrate in order to accomplish a multitude of different tasks in a diverse range of fields. The potential for device miniaturization made possible by MEMS micro-fabrication techniques has facilitated the development of many new applications, such as highly compact, non-invasive pressure sensors, accelerometers, gas sensors, etc. Besides their small physical footprint, such devices possess many other advantages compared to their macro-scale counterparts, including greater precision, lower power consumption, more rapid response, and the potential for low-cost batch production. One area in which MEMS technology has attracted particular attention is that of flow measurement. Broadly speaking, existing micro-flow sensors can be categorized as either thermal or non-thermal, depending upon their mode of operation. This paper commences by providing a high level overview of the MEMS field and then describes some of the fundamental thermal and nonthermal micro-flow sensors presented in the literature over the past 30 years or so.Keywords Cantilever type flow sensor Á Differential pressure flow sensor Á Lift force flow sensor Á Micro-electro-mechanical systems Á Resonating flow sensor Á Thermal flow sensor Origin and applications of MEMS technologyThe concept of micro-electro-mechanical systems (MEMS) dates back to the early 1960s, but only became an achievable reality when the tools and techniques originally developed for integrated circuit (IC) manufacturing became sufficiently advanced. Whereas electronic semiconductor devices are fabricated using IC process sequences, MEMS devices are produced by selectively etching away parts of the underlying silicon wafer or adding and patterning additional metallic and polymer layers to form the required mechanical and electromechanical devices. Typical MEMs micro-fabrication techniques include deposition [e.g. electroplating, sputtering, chemical vapor deposition (CVD), etc.], photolithography, and etching (e.g. wet etching, reactive ion etching (RIE), etc.]. Although still an emerging technology, MEMS devices are being increasingly deployed for mainstream commercial and industrial applications such as pressure sensors, accelerometers, gas sensors, RF switches, micro-mirrors, etc. (Löfdahl and Gadel-Hak 1999). In addition to the obvious advantages accruing from their diminutive scale (including a greater portability, a more discrete implementation and a reduced power consumption), MEMS devices permit the bulk

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“…In 1998, Ebefors et al (1998) presented a MEMS-based triple-hot-wire sensor with polyimide joints. As shown in Fig.…”

Section: Thermal Flow Sensorsmentioning

confidence: 99%

MEMS-based gas flow sensors

Wang

Chen

Chang

et al. 2009

Microfluid Nanofluid

151

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“…Often a variety of surface fences [3] or hot-wires [4] are used as the sensing element in the flow. As well as having the disadvantage of changing the flow, these components are very fragile and susceptible to damage from particles in the flow.…”

Section: State Of the Artmentioning

confidence: 99%

Robust pressure sensor for measurements in boundary layers of liquid fluids with medium total pressures

et al. 2011

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In this work, the latest results of the design, fabrication and characterization of a new MEMS piezoresistive pressure sensor are presented. It is made of silicon using a boron diffusion process to create piezoresistors. Significant changes in the layout as well as in the micro-fabrication process have been made, e.g. anodic bonding of a Pyrex cover on the backside. These lead to a very precise pressure sensor, which is tailor made for high dynamic measurements in fluids with a total pressure up to 4 bar. This new piezoresistive pressure sensor has been developed in order to meet the special requirements of measurements in fluid mechanics, particularly with regard to the non-intrusive nature of the sensor. The sensor development, starting with the simulation of mechanical stresses within the diaphragm is described. These calculations have lead to an optimized placement of the piezoresistors in order to achieve a maximum sensitivity. The result of this work is a sensor which has well known properties. Important parameters including sensitivity, resonance frequency and maximum load are described precisely. These are necessary to enable new measurements in the boundary layer of fluids. The experiments and the initial results, e.g. its linearity and its dynamic capability are demonstrated in several figures.

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“…Flow sensor had been developed in the past by researcher based on several principles including thermal (hot-wire) anemometry (Ebefors 1998). The hot-wire anemometers are based on the anemometer principle.…”

Section: Introductionmentioning

confidence: 99%

Review of MEMS flow sensors based on artificial hair cell sensor

et al. 2011

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An artificial hair cell sensor is the current technology based on a biological inspiration and is widely used in underwater applications including the glider, robotic and autonomous surface vehicle. These papers discuss a few strategies in relation to the principles of sensing, fabrication, performance, and preliminary measurement data. The MEMS flow sensor is generally needed to replace existing commercial sensors that are inadequate for some applications. Material also provides some advantages to the hair cell sensor. Some materials such as Polydimethylsilaxone and Polyurethane have been investigated. The sensing element is reviewed including the doped piezoresistors, strain gauge and force sensitive resistors. Performance and result of each design will be presented briefly. Finally, the importance and the need for modeling, simulation and experiments will be reviewed based on the latest achievements on that particular research area.

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Three dimensional silicon triple-hot-wire anemometer based on polyimide joints

Cited by 57 publications

References 12 publications

MEMS-based gas flow sensors

MEMS-based gas flow sensors

Robust pressure sensor for measurements in boundary layers of liquid fluids with medium total pressures

Review of MEMS flow sensors based on artificial hair cell sensor

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