Featured Research

from universities, journals, and other organizations

Flow from a nanoscale fluid jet measured: Jet measures 20 to 150 nanometers in diameter, just a few hundred water molecules across

Date:
October 28, 2013
Source:
Northwestern University
Summary:
Scientists have measured the flow from a fluid jet so tiny that it would require more than 8,000 years to fill a two-liter soda bottle.

A research team has recently verified the classical Landau-Squire theory in the world's tiniest submerged jet — in the range of 20 to 150 nanometers.
Credit: Image courtesy of Northwestern University

Fluid jets are all around us: from inkjet printing, to the "Old Faithful" geyser in Yellowstone National Park, to cosmological jets several thousand light years long.

Related Articles


A Northwestern University researcher with collaborators from Cambridge University, Oxford University, and Centro Nacional de Biotecnología have recently verified the classical Landau-Squire theory in the tiniest submerged jet. The diameter of their jets were in the range of 20 to 150 nanometers, which is the length of just a few hundred water molecules lined up in a row.

"The flow rate from this nanojet is in the range of tens of pico liters per second," said Sandip Ghosal, associate professor of mechanical engineering and (by courtesy) engineering sciences and applied mathematics at Northwestern's McCormick School of Engineering and Applied Science. "At this rate, if you had started to fill a two-liter soda bottle at the time the first pyramid was being built in Egypt, the bottle would be about half full now."

A paper describing the research, "A Landau-Squire Nanojet," was published October 14 in the journal Nano Letters.

The nanojet is designed around a glass "nano capillary," which the researchers fabricated by heating an ordinary glass capillary -- a hollow glass tube -- with a laser and gently pulling it until it broke, creating a fine tip. The researchers applied an electric voltage across the capillary, which was submerged in a salt solution to create an electroosmotic flow that then emerged as a jet.

To measure the jet stream, the researchers built a tiny anemometer -- a windmill-like device used for measuring wind speed -- from a polystyrene bead less than one-fiftieth the width of a human hair. The bead was held in place by an "optical trap," a finely focused laser beam that served as a spindle for the tiny anemometer. When the bead was positioned in front of the jet, it spun around, and a video camera picked up tiny fluctuations of light from a dimple on the bead.

The novel anemometry technique allowed the researchers to map out the vorticity and velocity fields of the nanojet and compare it to those predicted by the classical Landau-Squire solution of the Navier-Stokes equations, the 200-year-old equations that form the bedrock of classical physics. Their observations proved to be in remarkable agreement with the theory.

"The Navier-Stokes equations and everything derived from it are expected to go awry as we approach molecular scales, but no one knows how far down one can push before it breaks," Ghosal said. "We found that it works very nicely down to tens of nanometers."

The researchers also observed a phenomenon they call flow rectification: an asymmetry in the flow rate with respect to voltage reversal. They found that when the voltage is reversed, the capillary sucks in fluid as expected, but at a much lower rate. The capillary thus behaves like a semiconductor diode -- an electronic "valve" that allows current flow in only one direction -- but with fluid flowing in place of electrons.

The nanojet has a number of potential novel applications. One possible use is as an ultra-low-volume injector for transferring biomolecules into cells or vesicles, a process used in recombinant DNA technologies important in the production of human insulin and disease-resistant crops. Other possibilities include use as a "flow rectifier" in microfluidic logic circuits, the functional equivalent of semiconductor diodes in microelectronics, and also in applications involving nanoscale patterning and micro manipulation.

In addition to Ghosal, other authors include Nadanai Laohakunakorn and Ulrich F. Keyser of the University of Cambridge; Benjamin Gollnick and Fernando Moreno-Herrero of the Centro Nacional de Biotecnología; and Dirk G. A. L. Aarts and Roel P. A. Dullens of the University of Oxford. The research was conducted earlier this year when Ghosal was Leverhulme Trust Visiting Professor at the Cavendish Laboratory of Cambridge University.


Story Source:

The above story is based on materials provided by Northwestern University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Nadanai Laohakunakorn, Benjamin Gollnick, Fernando Moreno-Herrero, Dirk G. A. L. Aarts, Roel P. A. Dullens, Sandip Ghosal, Ulrich F. Keyser. A Landau–Squire Nanojet. Nano Letters, 2013; 131023092047008 DOI: 10.1021/nl402350a

Cite This Page:

Northwestern University. "Flow from a nanoscale fluid jet measured: Jet measures 20 to 150 nanometers in diameter, just a few hundred water molecules across." ScienceDaily. ScienceDaily, 28 October 2013. <www.sciencedaily.com/releases/2013/10/131028141545.htm>.
Northwestern University. (2013, October 28). Flow from a nanoscale fluid jet measured: Jet measures 20 to 150 nanometers in diameter, just a few hundred water molecules across. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2013/10/131028141545.htm
Northwestern University. "Flow from a nanoscale fluid jet measured: Jet measures 20 to 150 nanometers in diameter, just a few hundred water molecules across." ScienceDaily. www.sciencedaily.com/releases/2013/10/131028141545.htm (accessed October 23, 2014).

Share This



More Matter & Energy News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

3D Printed Instruments Make Sweet Music in Sweden

3D Printed Instruments Make Sweet Music in Sweden

Reuters - Innovations Video Online (Oct. 23, 2014) — Students from Lund University's Malmo Academy of Music are believed to be the world's first band to all use 3D printed instruments. The guitar, bass guitar, keyboard and drums were built by Olaf Diegel, professor of product development, who says 3D printing allows musicians to design an instrument to their exact specifications. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) — Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) — Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) — As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins