Microfluidic mixing under low frequency vibration

Oberti, Stefano; Neild, Adrian; Ng, Tuck Wah

doi:10.1039/b819739c

Cited by 63 publications

(40 citation statements)

References 10 publications

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“…Indeed the correlation of increased mass transfer co-efficient between two fluids given an added LLFV application has been experimentally verified by Hancil et al [31]. Further, Oberti et al, have shown enhanced mixing of particulate laden fluids in articulating channels (analogous to articulating blood vessels) secondary to external LLFV [32,33]. Accordingly, LLFV mixing devices such as produced by Resodyn  Acoustic Mixers (operable at a nominal frequency of 60 Hz) have found common use in industrial mixing of both fluids and solids.…”

Section: Discussionmentioning

confidence: 91%

Externally Applied Vibration at 50 Hz Facilitates Dissolution of Blood Clots In-Vitro

Hoffmann¹,

Gill²

2012

Am. J. Biomed. Sci.

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Background: Localized Low Frequency Vibration (LLFV) in the low sonic range is utilized for disruption of clots by direct contact in catheter applications. However enhanced clot dissolution whereby an LLFV source is applied external from a clotted lumen (such as to resemble a non-invasive therapy) has not been studied.Objective: To assess the effectiveness of low amplitude extra luminally applied 50 Hz LLFV in dissolution of 1 hr old clots immersed in Heparinized Saline.Methods: One hr old blood clots were each placed within a 3 ml syringe filled with 1.5 ml's of Heparinized Saline. LLFV was then applied against the external surface of each syringe with gentle stroke amplitude (~ 0.5 mm), an intensity within an order of magnitude expected to reach a thrombosed vessel (such as a coronary, pulmonary, cerebral, or peripheral artery), given if a substantially stronger application where to be applied non-invasively across the artery's overlying soft tissue barrier.Results: LLFV yielded statistically superior clot dissolution (25%) in comparison to the non vibrated controls (5%) (p<0.0003).Conclusions: Transluminally applied LLFV (50 Hz) accelerates clot dissolution in vitro. Further study in this area in-vivo appears warranted.

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Section: Discussionmentioning

confidence: 91%

Externally Applied Vibration at 50 Hz Facilitates Dissolution of Blood Clots In-Vitro

Hoffmann¹,

Gill²

2012

Am. J. Biomed. Sci.

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“…Proposed VC action includes transmission of oscillations from an external body surface to a thrombosed artery to cause mechanical agitation of clot and blood proximate the clot, while also potentially inducing a localized vasodilation response to the culprit vasculature. Turbulence induced at the blood clot interface is predictive (as shown in-vitro ) and inferable (in accordance with hydrodynamic mixing studies [Hancil V et al 1978, Neild A et al 2010, Oberti S et al 2009 ] to encourage systemic mixing of thrombolytics down an otherwise zero flow cerebral artery. Acoustic AIS therapy is generally problematic however as the cerebral arteries are mechanically shielded within the cranium.…”

Section: Introductionmentioning

confidence: 93%

Carotid Vibro-Compression: A Reperfusive Treatment for Acute Ischemic Stroke? Feasibility Data and a Potential Risk / Benefit Discussion in View to Animal Testing

Hoffmann¹,

Gill²

2017

J Exp Stroke Transl Med

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Slow uncertain reperfusion in Acute Ischemic Stroke (AIS) by intravenous thrombolysis has prompted search for alternative therapies. Pressure/flow disturbances from rapid compressions (20 -24 Hz) of a clotted flow tube remote from thrombosis site have shown to assist reflow. Carotid Vibro-Compression (VC), a potentially risky maneuver, may therefore enhance AIS reperfusion but verification is needed that vibro-compressions would transmit flow disturbances to the cerebral arteries. From a pool of 15 volunteers (mean age 48) carotid compressions (5 to 8 Hz, < = ~1 cm) (n =11) and vibration (30 Hz ~ 1 mm) (n = 10) were independently and together implemented with ipsilateral and contralateral Doppler flow monitoring of an intra-cranial artery. Doppler pulses from compressions were immediately demonstrated in all vessels (26 / 26) under all conditions. Pulses from vibration were observable in a majority of vessels (22 / 25), but signals were often challenging to obtain. Mean intra-cranial flow velocities trended to increase during compressions (46.1 ± 6 .4 cm/s vs. 44.0 ± 4.9 cm/s), but the difference was not statistically significant (p = 0.06). Carotid VC reliably transmits flow pulses to the cerebral vasculature, however vibration requires biofeedback to ensure device positioning. Carotid VC appears feasible for animal testing, but safety remains a major question.

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“…A solution to this problem was presented by Oberti et al (2009), andNelid et al (2010). In the work by Oberti et al (2009), the authors showed that mixing can be improved under the low frequency vibration of the whole microchip, whereas, Neild et al (2010), demonstrated a possibility in mixing improvement from low frequency pulsations of the entering fluid.…”

Section: Introductionmentioning

confidence: 99%

“…In the work by Oberti et al (2009), the authors showed that mixing can be improved under the low frequency vibration of the whole microchip, whereas, Neild et al (2010), demonstrated a possibility in mixing improvement from low frequency pulsations of the entering fluid. Similar conclusions can be found in the paper by Glasgow et al (2003) where the numerical analysis showed that mixing in the 2D T-shaped microchip was improved by low frequency (5 Hz) pulsations at one of the inlets.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis Of Mixing Under Low And High Frequency Pulsations At Serpentine Micromixers

Malecha

Malecha²

2014

Chemical and Process Engineering

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The numerical investigation of the mixing process in complex geometry micromixers, as a function of various inlet conditions and various micromixer vibrations, was performed. The examined devices were two-dimensional (2D) and three-dimensional (3D) types of serpentine micromixers with two inlets. Entering fluids were perturbed with a wide range of the frequency (0 -50 Hz) of pulsations. Additionally, mixing fluids also entered in the same or opposite phase of pulsations. The performed numerical calculations were 3D to capture the proximity of all the walls, which has a substantial influence on microchannel flow. The geometry of the 3D type serpentine micromixer corresponded to the physically existing device, characterised by excellent mixing properties but also a challenging production process . It was shown that low-frequency perturbations could improve the average mixing efficiency of the 2D micromixer by only about 2% and additionally led to a disadvantageously non-uniform mixture quality in time. It was also shown that high-frequency mixing could level these fluctuations and more significantly improve the mixing quality. In the second part of the paper a faster and simplified method of evaluation of mixing quality was introduced. This method was based on calculating the length of the contact interface between mixing fluids. It was used to evaluate the 2D type serpentine micromixer performance under various types of vibrations and under a wide range of vibration frequencies.

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Microfluidic mixing under low frequency vibration

Cited by 63 publications

References 10 publications

Externally Applied Vibration at 50 Hz Facilitates Dissolution of Blood Clots In-Vitro

Externally Applied Vibration at 50 Hz Facilitates Dissolution of Blood Clots In-Vitro

Carotid Vibro-Compression: A Reperfusive Treatment for Acute Ischemic Stroke? Feasibility Data and a Potential Risk / Benefit Discussion in View to Animal Testing

Numerical Analysis Of Mixing Under Low And High Frequency Pulsations At Serpentine Micromixers

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