Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bath toys show strength in numbers

22.02.2002


Floating crescents could self-assemble into circuits


Miniature floating craft can be programmed to move and assemble in complex ways.

Harvard chemists are playing with bath toys. Floating bubble-powered craft designed to attract and repel one another, are helping them model the machinations of groups such as foraging ants, nest-building termites or schools of fish1.

Group dynamics are not always obvious from individuals’ behaviour, but emerge from their interactions. Computer models can simulate such processes. However George Whitesides and his coworkers in Cambridge, Massachusetts hope that using real experimental systems to elicit emergent properties will have a crucial advantage.



They want to exploit the self-organization inherent in their toys’ collective motions. For instance to assemble machines or electronic circuits from components that automatically swim into position.

Whitesides’ team made thin half-moons of water-repelling plastic about the size of a little fingernail. When two discs get near enough on a watery surface their edges attract each other and stick loosely together. Chemically treating some of the plate edges so that they aren’t water-repellent suppresses the attraction. The team tailored the discs to attract and adhere along some edges but not others.

To make these plates self-propel, the researchers fixed a small piece of platinum-covered glass underneath one corner. When they set the discs adrift on the surface of hydrogen peroxide solution, the platinum acted as a catalyst, breaking down the hydrogen peroxide into oxygen gas. The bubbles released propelled the plates over the water surface at speeds of up to 2 cm per second for several hours.

The plates thus derive energy for their motion from their environment instead of carrying a fuel tank. Varying the catalysts or the peroxide concentration varies their speed. The asymmetric position of the platinum engine under each semicircular plate drives them into circulating movements. Which way they twirl depends on which side the engine sits.

If two plates that rotate in the same direction stick together, the assembly also rotates in that direction. If two oppositely rotating plates unite, their tendencies cancel out, and the pair moves more or less in a straight line.

So even in this very simple system a new property - straight-line motion - appears when the rotating individuals get together. "We believe", say the researchers, "that assemblies of tens or hundreds of components may show substantially more complex behaviours".

References
  1. Ismagilov, R. F., Schwartz, A., Bowden, N. & Whitesides, G. M. Autonomous movement and self-assembly. Angewandte Chemie International Edition, 41, 652 - 654, (2002).


PHILIP BALL | Nature News Service

More articles from Life Sciences:

nachricht What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Speed data for the brain’s navigation system

06.12.2016 | Health and Medicine

What happens in the cell nucleus after fertilization

06.12.2016 | Life Sciences

IHP presents the fastest silicon-based transistor in the world

05.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>