When a droplet of water meets with sound

an article by Burcu Gumuscu, PhD researcher at University of Twente

Water is a simple element found in abundance throughout nature, and for many, its commonplace nature may mask its importance. Even a single droplet of water is of high value in the science world: when manipulated with sound waves, a water droplet can be used in a tremendous number of applications. For example, this simple technique can contribute to reducing the high costs of diagnosis tools, ensure the correct dosage of many drugs for effective treatment, and detect contaminants or pathogenic threats in food industry. This actuation of droplets using sound waves on the micron-scale is known as acoustofluidics.

Fig. 1 Screenshots of the particle-laden sessile drops were captured before (a-d) and after (e-h) the SAW exposures

The science behind the above-mentioned advances lies in the handling of droplets with surface acoustic waves (SAW), produced by an interdigitated transducer interacting with a sessile water droplet. This interaction leads the droplets to dissipate the energy absorbed from SAW, giving rise to acoustic streaming flow (ASF) and acoustic radiation force (ARF). As a result, sound waves with different amplitudes travel across the droplet and create micro-streams. Mixing, merging, and even sorting of the suspended particles are therefore enabled due to these micro-streams. To achieve this, an in-depth understanding of the generation of these micro-streams and their effect on the suspended particles are crucial for better controlled manipulation of these on-demand applications.

Luckily, scientists in the Flow Control Laboratory at KAIST have recently published a comprehensive study in Lab on a Chip on the fate of different sized microparticles inside a droplet of water actuated by SAW. In this work, for the first time, polystyrene microparticles were reported to go under four different unexplored modes at high frequencies. The elastic character of the polystyrene particles exhibits significantly different behaviors under SAW applied with different frequencies. For example, large particles were found to concentrate at the center of the droplet while the smaller ones form a ring structure around the periphery.

Fig. 2 Separation of red 3 and green 5 µm polystyrene particles inside a (a) 5 and (b) 10 µm droplets

Other intermediate modes include particle concentration at the side of the droplet and ring formation close to the droplet center: all dependent on the particle size, applied frequency, ASF, and ARF. Flow Control Laboratory further explored this interesting behavior using microparticles in the range of 1-30 µm at nominal frequencies of 10, 20, 80, and 133 MHz. Figure 1 shows before and after manipulation of the water droplets. Better yet, SAW applied at high frequencies allowed the separation of different-sized microparticles in a water droplet as seen in Figure 2.

For a real demonstration of what happens when a droplet of water meets with sound, the movie appended to the article and included below is well worth the watch. Thanks to the improved understanding of the physics behind the technique, this self-contained microcentrifuge technology seems promising to further widen our horizons in both clinical and biological applications.



To download the full article for free* click the link below:

Acoustofluidic particle manipulation inside a sessile droplet: four distinct regimes of particle concentration
Ghulam Destgeer, Hyunjun Cho, Byung Hang Ha, Jin Ho Jung, Jinsoo Park and Hyung Jin Sung
Lab Chip
, 2016, 16, 660-667
DOI: 10.1039/C5LC01104C, Paper

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About the webwriter

Burcu Gumuscu is a PhD researcher in BIOS Lab on a Chip Group at University of Twente in The Netherlands. Her research interests include development of microfluidic devices for second generation sequencing, organ-on-chip development, and desalination of water on the micron-scale.

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*Access is free until 02/05/2016 through a registered RSC account.

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Pioneers of Miniaturization Lectureship 2016

Lab on a Chip and Corning Incorporated are proud to sponsor the eleventh Pioneers of Miniaturization Lectureship, to honour and support the up and coming, next generation of scientists who have significantly contributed to the understanding or development of miniaturised systems. This year’s Lectureship will be presented at the µTAS 2016 Conference in Dublin, Ireland, with the recipient receiving a prize of US$5,000.

Who should you nominate?

Early to mid-career scientists (maximum 15 years post completion of PhD).

Scientists who have demonstrated extraordinary contributions to the understanding or development of miniaturised systems.

How do you nominate?

Submit your nominations to Lab on a Chip Editor Sarah Ruthven at LOC-RSC@rsc.org

Nominations should include:

  • Full contact and affiliation details of the person making the nomination.
  • A letter of nomination with the candidate’s accomplishments and why the lectureship is deserved. (The nominee must be aware that he/she has been nominated for this lectureship.)
  • A list of the candidate’s relevant publications or recent work (all work should be original).
  • Candidate’s scientific CV stating PhD completion date; address; and full contact details.

Nomination Deadline: 1 June 2016

Who has won the Pioneers of Miniaturisation Lectureship in the past?

  • 2015: Professor Dino Di Carlo, University of California, Los Angeles, USA
  • 2014: Professor Sangeeta N. Bhatia, Massachusetts Institute of Techology, USA
  • 2013: Professor Shuichi Takayama, University of Michigan, USA
  • 2012: Professor Andrew deMello, ETH Zürich, Switzerland
  • 2011: Professor Ali Khademhosseini, Massachusetts Institute of Technology, USA
  • 2010: Professor Stephen Quake, Stanford University, USA
  • 2009: Professor Abe Lee, University of California, Irvine, USA
  • 2008: Dr Patrick Doyle, Massachusetts Institute of Technology, USA
  • 2007: Dr Manabu Tokeshi, Nagoya University, Japan
  • 2006: Dr David Beebe, University of Wisconsin, USA

Terms and Conditions

The Lectureship consists of the following elements:

  • A prize of US$5,000. No other financial contribution will be offered
  • A certificate recognising the winner of the lectureship
  • The awardee is required to give a short lecture at the 2016 µTAS Conference

The award is for early to mid-career scientists (maximum 15 years post completion of PhD).

The award is for extraordinary or outstanding contributions to the understanding or development of miniaturised systems. This will be judged mainly through their top 1-3 papers and/or an invention documented by patents/or a commercial product. Awards and honorary memberships may also be considered.

The winner will be expected to submit at least two significant publications to Lab on a Chip in the 12 months after the lectureship is awarded.

Nominations from students and self-nominations are not permissible.

The decision on the winner of the lectureship will be made by a panel of judges, and this decision will be final.

Sponsors

Corning Incorporated
Corning (www.corning.com) is one of the world’s leading innovators in materials science. For more than 160 years, Corning has applied its unparalleled expertise in specialty glass, ceramics, and optical physics to develop products that have created new industries and transformed people’s lives. Corning succeeds through sustained investment in R&D, a unique combination of material and process innovation, and close collaboration with customers to solve tough technology challenges. Corning’s businesses and markets are constantly evolving. Today, Corning’s products enable diverse industries such as consumer electronics, telecommunications, transportation, and life sciences. They include damage-resistant cover glass for smartphones and tablets; precision glass for advanced displays; optical fiber, wireless technologies, and connectivity solutions for high-speed communications networks; trusted products that accelerate drug discovery and manufacturing; and emissions-control products for cars, trucks, and off-road vehicles.

Lab on a Chip
The leading journal for miniaturization at the micro and nanoscale. Lab on a Chip supports research and development of miniaturization technologies and promotes interdisciplinary co-operation across all fields of science. The Journal also provides readers with a more fundamental understanding of miniaturization and related processes as well as the necessary tools for practical application of methods and devices.

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2015 Art in Science – Editorial

From microgalaxies to micro-oceans to Warhol’s cellular images

The 19th International Conference of Miniaturized Systems for Chemistry and Life Sciences held in Gyeonju, South Korea on October 2015 saw the 8th Art in Science competition.

The judges thought the quality of submissions was really high and the Lab on a Chip team would like to thank all the contributors. Please join us at Lab on a Chip in congratulating all of our prize winners.

You can read more information about this competition and its winners on Darwin R. Reyes’s Editorial in Issue 8.

The Art in Science award is sponsored by NIST and supported by MicroTAS, the Chemical and Biological Microsystems Society (CBMS) and the Lab on a Chip journal. The award consists of a monetary prize ($2500), an award certificate, and the coveted front cover of the Lab on a Chip journal.

We encourage you to participate in the 2016 Art in Science competition


2015 Winner: Through Warhol’s eyepiece, by Matteo Cornaglia

Image winner of the MicroTAS 2015 Art in Science award titled Through Warhol’s eyepiece by Matteo Cornaglia (Laboratory of Microsystems, EPFL).

Through Warhol's eyepiece by Matteo Cornaglia

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New microfluidic system for intracochlear drug delivery

an article by Claire Weston, PhD student at Imperial College London

William Sewell at Massachusetts Eye and Ear Infirmary and Harvard Medical School and Jeffrey Borenstein at the Charles Stark Draper Laboratory in Massachusetts have developed an automated micropump device for direct delivery of drugs into the perilymph fluid within the cochlea. This has potential for use in the treatment of sensorineural hearing loss and would remove the toxicity issues that are common when drugs are administered systemically. This is one of the most common forms of hearing loss and is caused by damage to the sensory hair cells or to the auditory nerve.

Components of the device and process flow for one drug delivery cycle

Due to the small volumes of perilymph fluid within the cochlea (~ 0.2 mL) and the sensitivity of the ear, the authors have developed a reciprocating delivery system, where an accurate volume of the concentrated drug can be infused and, once given time to distribute, the same volume of fluid can be withdrawn, resulting in zero overall net increase in cochlear fluid. The specific design also minimised the dead volume present in the device in order to reduce the amount of pumping needed, and by incorporating capacitors, prevented high flow rates during pumping, which can lead to cochlear damage.

The authors emphasise the need for a device that is small and lightweight enough to be implanted near to the cochlea and that is also able to administer precise sub-microliter volumes of fluid over several days or months. The microfluidic device presented in Lab on a Chip has been fabricated onto a ~4 x 3 cm chip and is capable of delivering accurate and repeatable volumes of fluid over more than 1000 pump strokes. The authors highlight that by incorporating the device onto a head mount, this particular design could be used in animal models for preclinical drug characterisation, where extensive studies are required.

All the fluidic components of this system have been incorporated into the chip, so that, if battery operated, it could be used as a stand-alone device. In this design, a separate controller was used; however, it is stated that the control circuitry could also be miniaturised and incorporated into the chip, for use with a battery. Efforts were also made to minimise the power consumption of the pump for this purpose. The main components of the device are a drug reservoir, a fluid storage capacitor which contains artificial perilymph for flushing the system, an infuse-withdraw line, and multiple valves to control the different steps of the drug delivery process, as shown in the diagram.

Dose control was successfully demonstrated by loading the pump with fluorescein as the test drug and monitoring the fluorescence of the aliquots collected following different dosage schemes. Several studies were also carried out on guinea pigs using a glutamate receptor antagonist as the test drug. This compound reversibly suppresses compound action potentials (CAPs) in the cochlea – monitoring changes in CAP amplitude and threshold can be used to test for hearing loss.

The results showed that fully reversible hearing loss was induced and this was used to estimate the optimum wait time between infusion and withdrawal for the reciprocating delivery. The distribution of the drug in the ear was also monitored by measuring changes to CAPs at different frequencies and comparing these to the known tonotopic organisation of the cochlea. To test for cochlear damage, the authors monitored another hearing response (distortion product otoacoustic emission) that was not expected to change, and determined that there was no acute mechanical damage.

This drug delivery system has excellent potential for use in clinical and preclinical trials and also for long term treatment of hearing loss using existing drugs. The potential for battery operation is particularly important, and is an aspect that the authors are now focusing on for future work.


To download the full article for free* click the link below:

Microfabricated reciprocating micropump for intracochlear drug delivery with integrated drug/fluid storage and electronically controlled dosing
Vishal Tandon, Woo Seok Kang, Tremaan A. Robbins, Abigail J. Spencer, Ernest S. Kim, Michael J. McKenna, Sharon G. Kujawa, Jason Fiering,  Erin E. L. Pararas, Mark J. Mescher, William F. Sewell, Jeffrey T. Borenstein
Lab Chip, 2016, 16, 829-846
DOI: 10.1039/C5LC01396H

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About the webwriter

Claire Weston is a PhD student in the Fuchter Group, at Imperial College London. Her work is focused on developing novel photoswitches and photoswitchable inhibitors.

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*Access is free until 05/04/2016 through a registered RSC account.

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Cleaning solution test doesn’t move contact lens wearers to tears

A Lab on a Chip article highlighted in Chemistry World article by Harriet Brewerton

In the US, over 30 million people wear contact lenses and each year around 60,000 contract serious eye infections that put them at risk of going blind. Thorough cleaning is vital to prevent bacterial build-up on the lens but research has also shown that an individual’s tear chemistry affects the effectiveness of cleaning solutions.

Personalised care products can prevent serious eye infections caused by ineffective contact lens cleaning solutions

The team use their device to demonstrate how tears impacts lens selection and care, and say it could be adapted for point-of-care testing in eye clinics.

Please visit Chemistry World to read the full article.

Contact lens-on-a-chip companion diagnostic for personalized medicine
Allan Guan, Yi Wang, Kenneth Scott Phillips and Zhenyu Li
Lab Chip
, 2016, Accepted Manuscript
DOI: 10.1039/C6LC00034G

*Access is free through a registered RSC account until 8th April 2016 – click here to register


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New YouTube Videos

Controlled single-cell deposition and patterning by highly flexible hollow cantilevers

Multilayered film microreactors fabricated by one-step thermal bonding technique with high reproducibility and their applications

Trapping and viability of swimming bacteria in an optoelectric trap

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