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 Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>