Intra-droplet acoustic particle focusing: simulations and experimental observations

Fornell, Anna; Garofalo, Fabio; Nilsson, Johan; Bruus, Henrik

doi:10.1007/s10404-018-2094-9

Cited by 17 publications

(12 citation statements)

References 38 publications

(40 reference statements)

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“…As mentioned earlier for high frequency ultrasound, standing waves are often formed in microchannels as the corresponding wavelength approaches that of the channel height or width. Particles in a standing wave experience acoustic radiation forces that move particles either to the pressure node or antinode, known as acoustophoresis, see Figure 1a [46][47][48][78][79][80]. Particle movement is influenced by the acoustic contrast factor [53,[80][81][82][83], which is a function of fluid and particle density, compressibility and the speed of sound in the mixture.…”

Section: Standing Acoustic Waves In Microchannels: Acoustophoretic Force and Streamingmentioning

confidence: 99%

Continuous Ultrasonic Reactors: Design, Mechanism and Application

et al. 2020

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Ultrasonic small scale flow reactors have found increasing popularity among researchers as they serve as a very useful platform for studying and controlling ultrasound mechanisms and effects. This has led to the use of these reactors for not only research purposes, but also various applications in biological, pharmaceutical and chemical processes mostly on laboratory and, in some cases, pilot scale. This review summarizes the state of the art of ultrasonic flow reactors and provides a guideline towards their design, characterization and application. Particular examples for ultrasound enhanced multiphase processes, spanning from immiscible fluid–fluid to fluid–solid systems, are provided. To conclude, challenges such as reactor efficiency and scalability are addressed.

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Section: Standing Acoustic Waves In Microchannels: Acoustophoretic Force and Streamingmentioning

confidence: 99%

Continuous Ultrasonic Reactors: Design, Mechanism and Application

et al. 2020

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“…It has previously been shown that to generate a strong and homogeneous standing wave field in two-phase systems, it is important to match the acoustic properties of the continuous phase and the dispersed phase. 35 Here, light mineral oil was used as a continuous phase as it has similar acoustic properties to water.…”

Section: Acoustophoresismentioning

confidence: 99%

A droplet acoustofluidic platform for time-controlled microbead-based reactions

Liu

Fornell

2021

Biomicrofluidics

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Droplet microfluidics is a powerful method used to characterize chemical reactions at high throughput. Often detection is performed via in-line optical readout, which puts high demands on the detection system or makes detection of low concentration substrates challenging. Here, we have developed a droplet acoustofluidic chip for time-controlled reactions that can be combined with off-line optical readout. The principle of the platform is demonstrated by the enzymatic conversion of fluorescein diphosphate to fluorescein by alkaline phosphatase. The novelty of this work is that the time of the enzymatic reaction is controlled by physically removing the enzymes from the droplets instead of using chemical inhibitors. This is advantageous as inhibitors could potentially interact with the readout. Droplets containing substrate were generated on the chip, and enzyme-coupled microbeads were added into the droplets via pico-injection. The reaction starts as soon as the enzyme/bead complexes are added, and the reaction is stopped when the microbeads are removed from the droplets at a channel bifurcation. The encapsulated microbeads were focused in the droplets by acoustophoresis during the split, leaving the product in the side daughter droplet to be collected for the analysis (without beads). The time of the reaction was controlled by using different outlets, positioned at different lengths from the pico-injector. The enzymatic conversion could be measured with fluorescence readout in a separate PDMS based assay chip. We show the ability to perform time-controlled enzymatic assays in droplet microfluidics coupled to an off-line optical readout, without the need of enzyme inhibitors.

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“…In the subsequent step on applying 136 MHz acoustic power the 3.2 mm particles remained traveling along the focused stream while the 4.8 m m particles were deflected to the opposite side of the channel, and thus, separated. The two stage TSAW based separation system was also used for separating particles of different sizes confined within a droplet (Park et al, 2017;Fornell et al, 2018b) as shown in Figure 12. In first stage an ultrasonic beam of 135 MHz pushes particles of both sizes (5 and 10 m m) to one side within the droplet then the low frequency (95 MHz) beam effects only the larger particles, thus the positions of both sizes are controlled and eventually a split of the droplet occurs at the Y-junction and the intradroplet separation take place.…”

Section: Sheathless Traveling Surface Acoustic Waves Particle Separation Techniquesmentioning

confidence: 99%

Evaluation of acoustic-based particle separation methods

Ahmad

Bozkurt

Farhanieh

2019

WJE

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Purpose This paper aims to Separation and sorting of biological cells is desirable in many applications for analyzing cell properties, such as disease diagnostics, drugs delivery, chemical processing and therapeutics. Design/methodology/approach Acoustic energy-based bioparticle separation is a simple, viable, bio-compatible and contact-less technique using, which can separate the bioparticles based on their density and size, with-out labeling the sample particles. Findings Conventionally available bioparticle separation techniques as fluorescence and immunomagnetic may cause a serious threat to the life of the cells due to various compatibility issues. Moreover, they also require an extra pre-processing labeling step. Contrarily, label-free separation can be considered as an alternative solution to the traditional bio-particle separation methods, due to their simpler operating principles and lower cost constraints. Acoustic based particle separation methods have captured a lot of attention among the other reported label-free particle separation techniques because of the numerous advantages it offers. Practical implications This study tries to briefly cover the developments of different acoustic-based particle separation techniques over the years. Unlike the conventional surveys on general bioparticles separation, this study is focused particularly on the acoustic-based particle separation. The study would provide a comprehensive guide for the future researchers especially working in the field of the acoustics, in studying and designing the acoustic-based particle separation techniques. Originality/value The study insights a brief theory of different types of acoustic waves and their interaction with the bioparticles is considered, followed by acoustic-based particle separation devices reported till the date. The integration of acoustic-based separation techniques with other methods and with each other is also discussed. Finally, all major aspects like the approach, and productivity, etc., of the adopted acoustic particle separation methods are sketched in this article.

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Intra-droplet acoustic particle focusing: simulations and experimental observations

Cited by 17 publications

References 38 publications

Continuous Ultrasonic Reactors: Design, Mechanism and Application

Continuous Ultrasonic Reactors: Design, Mechanism and Application

A droplet acoustofluidic platform for time-controlled microbead-based reactions

Evaluation of acoustic-based particle separation methods

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