Dynamic response of micro-pillar sensors measuring fluctuating wall-shear-stress

Brücker, Christoph; Bauer, Daniel P.; Chaves, H.

doi:10.1007/s00348-007-0282-6

Cited by 73 publications

(62 citation statements)

References 7 publications

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“…Its governing equation models the motion of a uniform, homogeneous, single-clamped cantilever beam due to a massflow by taking the impacts of inertia, bending, drag and viscous damping into consideration. It has been adopted by a number of researchers for flexible micropillars [31][32][33] . Traditionally, it has been used for absolutely linear bending for which the cantilever's tip displacement d tip is below 5% of the cantilever length.…”

Section: Discussionmentioning

confidence: 99%

Microsphere-assisted fabrication of high aspect-ratio elastomeric micropillars and waveguides

Paek

Kim

2014

Nat Commun

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High aspect-ratio micropillars are in strong demand for microtechnology, but their realization remains a difficult challenge, especially when attempted with soft materials. Here we present a direct drawing-based technique for fabricating micropillars with poly(dimethylsiloxane). Despite the material's extreme softness, our technique enables routine realization of micropillars exceeding 2,000 mm in height and 100 in aspect-ratio. It also supports in situ integration of microspheres at the tips of the micropillars. As a validation of the new structure's utility, we configure it into airflow sensors, in which the micropillars and microspheres function as flexible upright waveguides and self-aligned reflectors, respectively. Highlevel bending of the micropillar under an airflow and its optical read-out enables mm s À 1 scale-sensing resolution. This new scheme, which uniquely integrates high aspect-ratio elastomeric micropillars and microspheres self-aligned to them, could widen the scope of soft material-based microdevice technology.

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Section: Discussionmentioning

confidence: 99%

Microsphere-assisted fabrication of high aspect-ratio elastomeric micropillars and waveguides

Paek

Kim

2014

Nat Commun

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“…To verify that such a mechanism is plausible when hydrodynamic sensors must operate in a boundary layer (i.e., very close to the skin surface) flexible micropillars were used as near-wall flow sensors (cf. Brücker et al, 2005Brücker et al, , 2007. A crosscorrelation of the bending motions of these pillars did indeed produce an accurate estimate of the velocity vector along the direction of the neuromasts (micropillars).…”

Section: Introductionmentioning

confidence: 97%

Measuring Flow Velocity and Flow Direction by Spatial and Temporal Analysis of Flow Fluctuations

Chagnaud¹,

Brücker²,

Hofmann³

et al. 2008

J. Neurosci.

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If exposed to bulk water flow, fish lateral line afferents respond only to flow fluctuations (AC) and not to the steady (DC) component of the flow. Consequently, a single lateral line afferent can encode neither bulk flow direction nor velocity. It is possible, however, for a fish to obtain bulk flow information using multiple afferents that respond only to flow fluctuations. We show by means of particle image velocimetry that, if a flow contains fluctuations, these fluctuations propagate with the flow. A cross-correlation of water motion measured at an upstream point with that at a downstream point can then provide information about flow velocity and flow direction. In this study, we recorded from pairs of primary lateral line afferents while a fish was exposed to either bulk water flow, or to the water motion caused by a moving object. We confirm that lateral line afferents responded to the flow fluctuations and not to the DC component of the flow, and that responses of many fiber pairs were highly correlated, if they were time-shifted to correct for gross flow velocity and gross flow direction. To prove that a cross-correlation mechanism can be used to retrieve the information about gross flow velocity and direction, we measured the flow-induced bending motions of two flexible micropillars separated in a downstream direction. A cross-correlation of the bending motions of these micropillars did indeed produce an accurate estimate of the velocity vector along the direction of the micropillars.

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“…With the exception of the hot-wire array presented by Yang et al [28], biomimetic approaches picked up fluid motion by means of a flow-induced deflection of a cantilever-like or lamella-shaped structure (an artificial cupula), which was detected by piezo-electric [38], resistive [39][40][41][42][43], capacitive [44][45][46], ionic polymer-metal composite (IPMC)-based [29,47] or optical [48][49][50][51] read-out techniques.…”

Section: Biomimetic Flow Sensors: State Of the Artmentioning

confidence: 99%

“…One exception are artificial SNs fabricated by means of thick-film technology [48][49][50]. However, the exposed position of SNs used in most bio-inspired sensors increases the risk of mechanical damage, either by the drag forces induced by high flow velocities and/or by mechanical ablation.…”

Section: Biomimetic Flow Sensors: State Of the Artmentioning

confidence: 99%

Micro-Machined Flow Sensors Mimicking Lateral Line Canal Neuromasts

et al. 2015

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Fish sense water motions with their lateral line.The lateral line is a sensory system that contains up to several thousand mechanoreceptors, called neuromasts. Neuromasts occur freestanding on the skin and in subepidermal canals. We developed arrays of flow sensors based on lateral line canal neuromasts using a biomimetic approach. Each flow sensor was equipped with a PDMS (polydimethylsiloxane) lamella integrated into a canal system by means of thick-and thin-film technology. Our artificial lateral line system can estimate bulk flow velocity from the spatio-temporal propagation of flow fluctuations. Based on the modular sensor design, we were able to detect flow rates in an industrial application of tap water flow metering. Our sensory system withstood water pressures of up to six bar. We used finite element modeling to study the fluid flow inside the canal system and how this flow depends on canal dimensions. In a second set of experiments, we separated the flow sensors from the main stream by means of a flexible membrane. Nevertheless, these biomimetic neuromasts were still able to sense flow fluctuations. Fluid separation is a prerequisite for flow measurements in medical and pharmaceutical applications.

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Dynamic response of micro-pillar sensors measuring fluctuating wall-shear-stress

Cited by 73 publications

References 7 publications

Microsphere-assisted fabrication of high aspect-ratio elastomeric micropillars and waveguides

Microsphere-assisted fabrication of high aspect-ratio elastomeric micropillars and waveguides

Measuring Flow Velocity and Flow Direction by Spatial and Temporal Analysis of Flow Fluctuations

Micro-Machined Flow Sensors Mimicking Lateral Line Canal Neuromasts

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