Deflection and maximum load of microfiltration membrane sieves made with silicon micromachining

Rijn, C.J.M. van; Wekken, M. van der; Nijdam, W.; Elwenspoek, Michael Curt

doi:10.1109/84.557530

Cited by 108 publications

(104 citation statements)

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“…This work focuses on airborne particles in the range of 1 to 10 pin [I], and micromachined membranes with perforations are ideal candidates for such filters. Although several MEMS filters [2,3,4] have been reported in the past, a comprehensive study of their strength and fluid dynamic performance is not available. For MEMS membrane filters to be effective, various requirements must be met.…”

Section: Introductionmentioning

confidence: 99%

Micromachined membrane particle filters

Yang

Tai

et al. 1999

Sensors and Actuators A: Physical

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We report herr several particle membrane filters (8 x 8 mn2) with circular, hexagonal and rectangular through holes. By varying hole dimensions from 6 to 12 pm, opening factors from 4 to 45 ?4 arc achieved. In order to improve the filter robustness, a composite silicon nitridelparylene membrane technology is developed. More importantly, fluid dynamic performance of the filters is also studied by both experiments and numerical simulations. It is found that the gaseous flow through the filters depends strongly on opening factors, and the measured pressure drops are much lower than that from numerical simulation using the Navier-Stokes equation. Interestingly, surface velocity slip can only account for a minor part of the discrepancy. This suggests that a very interesting topic for micro fluid mechanics research is identified.

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Section: Introductionmentioning

confidence: 99%

Micromachined membrane particle filters

Yang

Tai

et al. 1999

Sensors and Actuators A: Physical

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“…However, as will be shown in the next section, the mechanical strength of the membranes strongly depends on their shortest dimension [27], therefore increasing their width will result in weaker membranes. An alternative way to increase the porosity is to decrease the pitch of the slits.…”

Section: A Etching Of Siliconmentioning

confidence: 99%

“…It can safely be assumed that the mechanical strength of the silicon support that surrounds the Pd-Ag membranes is much higher than that of a single Pd-Ag membrane, therefore the strength of the whole membrane module will be mainly determined by that of a single membrane. Van Rijn et al [27] derived an equation that can be used to estimate the maximum transmembrane pressure for a thin membrane of composed of a ductile material (2) where is the thickness of the membrane, the length of the shortest side of the membrane, the yield stress and the Young's modulus of the membrane material. Several values of and for thick foils of Pd and Ag are given in Table I [28].…”

Section: B Mechanical Strength Of the Membranesmentioning

confidence: 99%

“…4 the width of the etched slit is estimated to be about 28 , while its initial width was defined by lithography to be 23 . This widening of the etched slit should be characterized exactly and taken into account during the design, for two main reasons: 1) a wider slit would imply a wider membrane, which would have a lower mechanical strength (membrane strength strongly depends on membrane width [27]) and 2) unexpected widening of the slits would make the determination of the total free membrane area, i.e., the separation area, difficult. Slit widening is due to a nonzero etch rate of the vertical formula planes, which depends on the accuracy of alignment of the mask patterns to the planes (this factor was reduced to a minimum in our work by using the previously described fan-shaped pattern to find the exact planes), but also on etching conditions [25], [26].…”

Section: A Etching Of Siliconmentioning

confidence: 99%

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Microfabrication of palladium-silver alloy membranes for hydrogen separation

Tong

Berenschot

Boer

et al. 2003

J. Microelectromech. Syst.

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“…It is especially important in PME, where whole emulsion, rather than a pure dispersed phase, is pressed through the membrane. Typical microsieves used in ME are nickel microengineered membranes manufactured using UV-LIGA process (Nazir et al, 2011;Schadler and Windhab, 2006;Egidi et al, 2008), silicon nitride Aquamarijn microsieves fabricated by reactive ion etching (RIE) (van Rijn et al, 1997), stainless steel membranes fabricated by pulsed laser drilling (Dowding et al, 2001;Vladisavljević and Williams, 2006;Geerken et al, 2008) or end-milling , and microchannel arrays fabricated in single crystal silicon by Deep Reactive Ion Etching (DRIE) (Kobayashi et al, 2003) or in PMMA by X-ray lithography and wet etching (Kobayashi et al, 2008b). The fabrication of microengineered membranes for ME is described by Vladisavljević et al (2012).…”

Section: Microengineered Membranesmentioning

confidence: 99%

Structured microparticles with tailored properties produced by membrane emulsification

Vladisavljević

2015

Advances in Colloid and Interface Science

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This paper provides an overview of membrane emulsification routes for fabrication of structured microparticles with tailored properties for specific applications. Direct (bottom-up) and premix (top-down) membrane emulsification processes are discussed including operational, formulation and membrane factors that control the droplet size and droplet generation regimes. A special emphasis was put on different methods of controlled shear generation on membrane surface, such as cross flow on the membrane surface, swirl flow, forward and backward flow pulsations in the continuous phase and membrane oscillations and rotations. Droplets produced by membrane emulsification can be used for synthesis of particles with versatile morphology (solid and hollow, matrix and core/shell, spherical and non-spherical, porous and coherent, composite and homogeneous), which can be surface functionalised and coated or loaded with macromolecules, nanoparticles, quantum dots, drugs, phase change materials and high molecular weight gases to achieve controlled/targeted drug release and impart special optical, chemical, electrical, acoustic, thermal and magnetic properties. The template emulsions including metal-in-oil, solid-in-oil-in-water, oil-in-oil, multilayer, and Pickering emulsions can be produced with high encapsulation efficiency of encapsulated materials and narrow size distribution and transformed into structured particles using a variety of different processes, such as polymerisation (suspension, mini-emulsion, interfacial and in-situ), ionic gelation, chemical crosslinking, melt solidification, internal phase separation, layer-by-layer electrostatic deposition, particle self-assembly, complex coacervation, spray drying, sol-gel processing, and molecular imprinting. Particles fabricated from droplets produced by membrane emulsification include nanoclusters, colloidosomes, carbon aerogel particles, nanoshells, polymeric (molecularly imprinted, hypercrosslinked, Janus and core/shell) particles, solder metal powders and inorganic particles. Membrane 2 emulsification devices operate under constant temperature due to low shear rates on the membrane surface, which range from (1−10) × 10 3 s −1 in a direct process to (1−10) × 10 4 s −1 in a premix process.Keywords: Membrane Emulsification; Polymeric microsphere; Microgel; Janus Particle; Core/Shell Particle, Colloidosome. Membrane emulsificationMembrane emulsification (ME) involves preparation of emulsions by pressing a pure dispersed phase or pre-emulsified mixture of the dispersed and continuous phase through a microporous membrane under controlled injection rate and shear conditions. In direct membrane emulsification (DME), one liquid (a dispersed phase) is injected through a microporous membrane into another immiscible liquid (the continuous phase) (Nakashima et al., 1991;, which leads to the formation of droplets at the membrane/continuous phase interface ( Figure 1a). In premix membrane emulsification (PME) (Figure 1b), a pre-emulsion is pressed through the membrane (...

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Deflection and maximum load of microfiltration membrane sieves made with silicon micromachining

Cited by 108 publications

References 3 publications

Micromachined membrane particle filters

Micromachined membrane particle filters

Microfabrication of palladium-silver alloy membranes for hydrogen separation

Structured microparticles with tailored properties produced by membrane emulsification

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