Re-configurable fluid circuits by PDMS elastomer micromachining

Armani, Andrea M.; Liu, C.; Aluru, Narayan

doi:10.1109/memsys.1999.746817

Cited by 330 publications

(261 citation statements)

References 4 publications

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“…Snap-in of the cantilever is apparent, although this was reduced in later experiments by coating cantilevers with Parylene C. curves with the Hertz model to derive an estimate of the elastic moduli of both materials. The effective elastic modulus of PDMS was comparable to values obtained by using other methods (17)(18)(19)(20) (Table 1). The effective modulus of agarose gels increased with agarose concentration (Fig.…”

Section: Resultssupporting

confidence: 81%

Analysis of nematode mechanics by piezoresistive displacement clamp

Park¹,

Goodman

Pruitt³

2007

Proc. Natl. Acad. Sci. U.S.A.

145

164

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Studying animal mechanics is critical for understanding how signals in the neuromuscular system give rise to behavior and how force-sensing organs and sensory neurons work. Few techniques exist to provide forces and displacements appropriate for such studies. To address this technological gap, we developed a metrology using piezoresistive cantilevers as force-displacement sensors coupled to a feedback system to apply and maintain defined load profiles to micrometer-scale animals. We show that this system can deliver forces between 10 ؊8 and 10 ؊3 N across distances of up to 100 m with a resolution of 12 nN between 0.1 Hz and 100 kHz. We use this new metrology to show that force-displacement curves of wild-type nematodes (Caenorhabditis elegans) are linear. Because nematodes have approximately cylindrical bodies, this finding demonstrates that nematode body mechanics can be modeled as a cylindrical shell under pressure. Little is known about the relative importance of hydrostatic pressure and shell mechanics, however. We show that dissipating pressure by cuticle puncture or decreasing it by hyperosmotic shock has only a modest effect on stiffness, whereas defects in the dpy-5 and lon-2 genes, which alter body shape and cuticle proteins, decrease and increase stiffness by 25% and 50%, respectively. This initial analysis of C. elegans body mechanics suggests that shell mechanics dominates stiffness and is a first step in understanding how body mechanics affect locomotion and force sensing.biomechanics ͉ Caenorhabditis elegans ͉ microelectromechanical systems A nalyses of the nematode Caenorhabditis elegans and its mutants enable systematic study of the interplay between genes and behaviors that range from simple movement to successful mating. C. elegans and other nematodes move in a sinusoidal fashion by generating waves of alternating dorsal and ventral muscle contraction. These waves of muscle contraction produce local bending in the cuticle, which is opposed by a high hydrostatic pressure (1, 2). In the laboratory and in the natural soil environment, C. elegans crawls across surfaces in a thin layer of moisture. The transformation of signals in the neuromuscular plant into behavior is constrained by body mechanics. Similarly, body mechanics determines how loads applied to the outer body surface are conveyed to mechanosensory neurons. To learn more, we developed a piezoresistive (PR)-based system with force and displacement ranges that are unavailable with existing methods.The nematode body plan consists of an outer tube separated from an inner tube by a fluid-filled pseudocoelom (Fig. 1). The cuticle, hypodermis, excretory system, neurons, and longitudinal muscles comprise the outer tube or shell, and the pharynx, intestine, and gonad form the inner tube (3). Internal tissues are under pressures on the order of 2-30 kPa (1), suggesting that nematodes have a shell-type hydrostatic skeleton. Very little is known about the relative importance of hydrostatic pressure and cuticle structure and elasticity to overall b...

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Section: Resultssupporting

confidence: 81%

Analysis of nematode mechanics by piezoresistive displacement clamp

Park¹,

Goodman

Pruitt³

2007

Proc. Natl. Acad. Sci. U.S.A.

145

164

View full text Add to dashboard Cite

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“…For all three cases, the fluid was taken to be water at 24 • C, which is (to a very good approximation) an incompressible fluid with constant density ρ = 997.3 kg/m 3 and constant viscosity µ = 9.14 × 10 −4 Pa·s. The material properties of PDMS remain the topic of active research [36,37,38,39,40], with some studies even suggesting a nonlinear mechanical response [41]. As a result, determining the linear elastic properties (i.e., Young's modulus and Poisson ratio) of the PDMS top wall for our three data sets was challenging.…”

Section: Materials Propertiesmentioning

confidence: 99%

Static response of deformable microchannels: a comparative modelling study

Shidhore

Christov

2018

J. Phys.: Condens. Matter

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Abstract. We present a comparative modelling study of fluid-structure interactions in microchannels. Through a mathematical analysis based on plate theory and the lubrication approximation for low-Reynolds-number flow, we derive models for the flow rate-pressure drop relation for long shallow microchannels with both thin and thick deformable top walls. These relations are tested against full three-dimensional two-way-coupled fluid-structure interaction simulations. Three types of microchannels, representing different elasticity regimes and having been experimentally characterized previously, are chosen as benchmarks for our theory and simulations. Good agreement is found in most cases for the predicted, simulated and measured flow rate-pressure drop relationships. The numerical simulations performed allow us to also carefully examine the deformation profile of the top wall of the microchannel in any cross section, showing good agreement with the theory. Specifically, the prediction that span-wise displacement in a long shallow microchannel decouples from the flow-wise deformation is confirmed, and the predicted scaling of the maximum displacement with the hydrodynamic pressure and the various material and geometric parameters is validated.

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“…Armani et al 8 measured the elastic modulus of an un-named brand of PDMS at the standard 10:1 ratio, and with twice the amount of cross-linker, a 10:2 ratio. Young's modulus increased from 750 to 870 kPa, only a 16% increase.…”

Section: Alternatives To Standard Pdmsmentioning

confidence: 99%

“…After curing, the daughter mold is peeled off the master. Here its high elongation at break ͑50%͒, 6 high Poisson ratio ͑0.5͒, 8 and low surface free energy allow challenging chip features, such as pillars to elongate, narrow, and release from the master with relatively little force. After its release the daughter mold can be reversibly or permanently sealed to a variety of surfaces.…”

Section: Introductionmentioning

confidence: 99%

A method for reducing pressure-induced deformation in silicone microfluidics

Inglis

2010

Biomicrofluidics

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Poly͑dimethylsiloxane͒ or PDMS is an excellent material for replica molding, widely used in microfluidics research. Its low elastic modulus, or high deformability, assists its release from challenging molds, such as those with high feature density, high aspect ratios, and even negative sidewalls. However, owing to the same properties, PDMS-based microfluidic devices stretch and change shape when fluid is pushed or pulled through them. This paper shows how severe this change can be and gives a simple method for limiting this change that sacrifices few of the desirable characteristics of PDMS. A thin layer of PDMS between two rigid glass substrates is shown to drastically reduce pressure-induced shape changes while preserving deformability during mold separation and gas permeability.

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Re-configurable fluid circuits by PDMS elastomer micromachining

Cited by 330 publications

References 4 publications

Analysis of nematode mechanics by piezoresistive displacement clamp

Analysis of nematode mechanics by piezoresistive displacement clamp

Static response of deformable microchannels: a comparative modelling study

A method for reducing pressure-induced deformation in silicone microfluidics

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