Researchers at the Max Planck Institute for Intelligent Systems, the Institute for Bioengineering of Catalonia (IBEC) and the University of Stuttgart have revealed in an article in Nature Communications that micromotors can be guided using tiny topographical patterns on the surfaces over which they swim.
Samuel Sánchez and Mykola Tasinkevych's ‘microswimmers’ are usually guided through fluids using specially engineered magnetic multilayer coatings, which combined with external magnetic fields, helps to control their trajectory.
An active particle approaches a micro-fabricated step and orients along it due to chemical activity and hydrodynamic interactions.
MPI for Intelligent Systems, Stuttgart
This new study, the result of a collaboration between experimental research and theory, demonstrates that the particles can use the features of the surfaces over which they swim to change their direction of motion.
“Micromotors tend to settle and move near surfaces, and we’ve seen that this tends to interfere with their swimming behaviour,” says group leader and ICREA research professor Samuel, who heads the Smart Nano-Bio-Devices group at IBEC and Stuttgart’s MPI-IS. “This led us to explore new methods to guide micromotors using surface alterations.”
Using a microfabrication process, the researchers modified surfaces to create a series of indentations or steps, several times smaller than the radius of the particle, which a specific type of micromotors – Janus particles, whose surfaces have two or more distinct physical properties – can use as signals to follow a particular path. This strategy is inspired by the one used by molecular motors in natural systems, where inside the cell, motor proteins bind to the cytoskeleton filaments to achieve directional motion.
The Janus particles are prepared by coating half of a silica particle with platinum. While the platinum face acts as a catalyst in hydrogen peroxide, the silica side remains inert, an asymmetry in chemical properties that leads to a self-propelled motion of these colloids.
The researchers noticed that the particles tend to have a stable orientation parallel to the surface, and exploited this phenomenon to guide the particles along sub-micron sized steps. They were able to demonstrate that the chemical activity of the particles and the associated hydrodynamic interactions with the nearby surfaces are responsible for the observed phenomenon.
“This finding opens up the possibility of guiding these particles along complex pathways using small changes in the surface,” explains Samuel. “This can have significant implications for the design of new artificial micromotors for a variety of applications.”
Simmchen, J., Katuri, J., Uspal, W.E., Popescu, M.N., Tasinkevych, M., and Sanchez, S. (2016). Sculpted topographical pathways guide chemical microswimmers. Nature Communications Volume: 7, Article number: 10598, DOI:10.1038/ncomms10598
Annette Stumpf | Max-Planck-Institut für Intelligente Systeme
Measurement of thoughts during knowledge acquisition
25.03.2019 | Max-Planck-Institut für Kognitions- und Neurowissenschaften
Important Progress in the Fight against Testicular Cancer
25.03.2019 | Universität Bremen
DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.
The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
25.03.2019 | Life Sciences
25.03.2019 | Life Sciences
25.03.2019 | Life Sciences