Milliseconds mixing in microfluidic channel using focused surface acoustic wave

Zeng, Qian; Guo, Feng; Yao, Liangzhong; Zhu, Hongwei; Zheng, Lijuan; Guo, Zhi-Xiao; Liu, W.; Chen, Y.; Guo, Shishang; Zhao, Xingzhong

doi:10.1016/j.snb.2011.08.075

Cited by 61 publications

(27 citation statements)

References 18 publications

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“…Considerably faster mixing has so far only been reported for smaller systems and microfluidic devices. Two laminar flows were mixed in 7 ms by an oscillating gas bubble trapped inside a micro channel or using surface acoustic waves (SAW) in 11 ms …”

Section: Resultsmentioning

confidence: 99%

Novel electrodynamic oscillation technique enables enhanced mass transfer and mixing for cultivation in micro‐bioreactor

Frey

Vorländer

Rasch

et al. 2019

Biotechnology Progress

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Micro‐bioreactors (MBRs) have become an indispensable part for modern bioprocess development enabling automated experiments in parallel while reducing material cost. Novel developments aim to further intensify the advantages as dimensions are being reduced. However, one factor hindering the scale‐down of cultivation systems is to provide adequate mixing and mass transfer. Here, vertical oscillation is demonstrated as an effective method for mixing of MBRs with a reaction volume of 20 μL providing adequate mass transfer. Electrodynamic exciters are used to transduce kinetic energy onto the cultivation broth avoiding additional moving parts inside the applied model MBR. The induced vertical vibration leads to oscillation of the liquid surface corresponding to the frequency and displacement. On this basis, the resonance frequency of the fluid was identified as the most decisive factor for mixing performance. Applying this vertical oscillation method outstanding mixing times below 1 s and exceptionally high oxygen transport with volumetric mass transfer coefficients (kLa) above 1,000/hr can be successfully achieved and controlled. To evaluate the applicability of this vertical oscillation mixing for low volume MBR systems, cultivations of Escherichia coli BL21 as proof‐of‐concept were performed. The dissolved oxygen was successfully online monitored to assure any avoidance of oxygen limitations during the cultivation. The here presented data illustrate the high potential of the vertical oscillation technique as a flexible measure to adapt mixing times and oxygen transfer according to experimental demands. Thus, the mixing technique is a promising tool for various biological and chemical micro‐scale applications still enabling adequate mass transfer.

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Section: Resultsmentioning

confidence: 99%

Novel electrodynamic oscillation technique enables enhanced mass transfer and mixing for cultivation in micro‐bioreactor

Frey

Vorländer

Rasch

et al. 2019

Biotechnology Progress

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show abstract

“…The vibration can be induced in a number of ways, including the use of a resonating piezoelectric disk causing control of the size of bubble produced in a flow-focusing junction 25 or by use of surface acoustic waves (SAW). [37][38][39] In two phase microfluidic systems, SAW has been used for mixing, 40 control of droplet size, 41 individual droplet production, 42 droplet merging 43 and sorting droplets at single 44 and multiple Y-junctions. They have been used for particle concentration, 28,29 trajectory control 30,31 and sorting, 32,33 for atomization, 34,35 for sessile droplet displacement 36 and for manipulating cells.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic plug steering using surface acoustic waves

2015

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Digital microfluidic systems, in which isolated droplets are dispersed in a carrier medium, offer a method to study biological assays and chemical reactions highly efficiently. However, it's challenging to manipulate these droplets in closed microchannel devices. Here, we present a method to selectively steer plugs (droplets with diameters larger than the channel's width) at a specially designed Y-junction within a microfluidic chip. The method makes use of surface acoustic waves (SAWs) impinging on a multiphase interface in which an acoustic contrast is present. As a result, the liquid-liquid interface is subjected to acoustic radiation forces. These forces are exploited to steer plugs into selected branches of the Y-junction. Furthermore, the input power can be finely tuned to split a plug into two uneven plugs. The steering of plugs as a whole, based on plug volume and velocity is thoroughly characterized. The results indicate that there is a threshold plug volume after which the steering requires elevated electrical energy input. This plug steering method can easily be integrated to existing lab-on-a-chip devices and it offers a robust and active plug manipulation technique in closed microchannels.

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“…9 It is reported that microfluidic operations, such as microfluidic generation, microfluidic transportation, mixing, particles manipulation, particle separation and microfluidic reaction, have been implemented on piezoelectric microfluidic devices. [10][11][12][13][14][15] However, the form of the working fluid on piezoelectric microfluidic devices is almost a microdroplet. The evaporation of the microdroplet on piezoelectric substrate is one of main obstacles of successful application in biochemical analysis.…”

Section: Introductionmentioning

confidence: 99%

A surface acoustic wave micropump to pump fluids from a droplet into a closed microchannel using evaporation and capillary effects

2014

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A new method for converting a microdroplet on a piezoelectric substrate into continuous fluid flow in microchannels is presented. An interdigital transducer with 27.5 MHz center frequency is fabricated on a 1280 yx-LiNbO3 piezoelectric substrate for exciting surface acoustic wave. A PDMS (Polydimethylsiloxane) microchannel is mounted on the piezoelectric substrate. One end of the microchannel is connected with water absorbing paper, while the other end of the microchannel is in touch with a droplet to be converted. The surface acoustic wave is used for controlling the evaporation velocity of the fluid in the microchannel. Part of fluid in the droplet can be entered into the microchannel and transported there due to the evaporation and capillary effects. Red dye solution is used to demonstrate the conversion of the droplet and the transportation of the fluid in the microchannel. Results show that the droplet on the piezoelectric substrate can successfully be converted into continuous fluid. The flow velocity is increased with the power of the electric signal applied to the interdigital transducer. Average flow velocity is 0.0235μl/s when the power of the electric signal is 30.0dBm. The work is helpful for piezoelectric microfluidic devices for biochemical analysis.

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Milliseconds mixing in microfluidic channel using focused surface acoustic wave

Cited by 61 publications

References 18 publications

Novel electrodynamic oscillation technique enables enhanced mass transfer and mixing for cultivation in micro‐bioreactor

Novel electrodynamic oscillation technique enables enhanced mass transfer and mixing for cultivation in micro‐bioreactor

Microfluidic plug steering using surface acoustic waves

A surface acoustic wave micropump to pump fluids from a droplet into a closed microchannel using evaporation and capillary effects

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