A swarm of tiny machines, speeding in concert through the bloodstream to repair an organ or deliver a drug to its target area, microrobots working together to construct a nanotechnological component—although it sounds like science fiction, it is a thoroughly realistic future scenario.
Amazing progress has already been made in the production of autonomous nano- and micromotors, but the little machines have continued to lack in team spirit. To complete challenging tasks, the individual machines must communicate and cooperate with each other.
Researchers led by Ayusman Sen at Pennsylvania State University (USA) have now introduced silver chloride microparticles that can “swarm” together, almost like living single-celled organisms. As reported in the journal Angewandte Chemie, irradiation with UV light causes the particles to give off “signal substances” that “attract” other particles.
Living cells and organisms are able to exchange information with each other to accomplish tasks as a team. Single-celled slime molds, for example, living in unfavorable conditions thus release a special substance. Neighboring slime molds follow the gradient of this signal substance and aggregate in the form of a multi-celled fruiting body. The silver chloride particles used by Sen’s team, which are about 1µm in size, behave in a similar fashion when irradiated with UV light. Silver chloride decomposes under UV light, releasing ions that act as both a propulsion mechanism and signal substance.
This phenomenon is based on diffusiophoresis, the movement of particles along an electrolyte gradient. The silver chloride particles “swim” toward a higher ion concentration. Because of irregularities in the surfaces of the particles and non-uniform irradiation, the degradation of the particles is asymmetric. Different quantities of ions are released in different places on the surface, which results in a local ion gradient around the particles. The particle thus produces its own ion gradient, which propels it at speeds up to 100 µm/s (self-diffusiophoresis). Neighboring sliver chloride particles follow the ion gradient of the solution and “swim” to regions of higher particle density. After several minutes, this results in small, stable “swarms” of particles. Photochemically inactive silicon dioxide particles also react to the ion signal, aggregating around the silver chloride particles.
This system can be used as a nonbiological model for communication between cells. Most importantly though, it represents a new design principle for “intelligent” synthetic nano- or micromachines that can work together as a team.
Author: Ayusman Sen, The Pennsylvania State University, University Park (USA), http://research.chem.psu.edu/axsgroup/dr_sen.html
Title: Schooling Behavior of Light-Powered Autonomous Micromotors in Water
Angewandte Chemie International Edition 2009, 48, No. 18, 3308–3312, doi: 10.1002/anie.200804704
What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
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...
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...
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...
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,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
06.12.2016 | Materials Sciences
06.12.2016 | Medical Engineering
06.12.2016 | Power and Electrical Engineering