Many bacteria are able to “swim” through liquids by means of a flagellum. When doing this, some bacteria follow attractants, some flee from harmful substances, and others align themselves using light, gravity, or magnetic fields.
These processes may also play a role in infections. Following a swimming bacterium without influencing its motion is difficult. Nanotechnology researchers are also interested in determining the motion of nanoparticles, which would be useful for the development of nanomotors, for example.
A team from the Universities of Oxford and Cambridge (UK) has now developed a new, electrochemical method for locating microscale objects as they move through a liquid. As they report in the journal Angewandte Chemie, researchers led by Richard G. Compton were able to use an array of microelectrodes to follow the two-dimensional motion of a tiny, individual basalt sphere in space and time.
The British researchers’ new process is based on a simple arrangement of four tiny electrodes (150×150 µm) at the bottom of a small cell. Each electrode can be addressed individually. In order to demonstrate that their approach works, the researchers carried out experiments with a basalt sphere with a diameter of about 330 µm. They used a magnet underneath the base of the cell to move the magnetic basalt sphere. The magnet was positioned by means of a stepper motor.
Inside the cell is a solution containing an electroactive compound. When the sphere comes close to one of the microelectrodes, it gets in the way of the molecules of this compound, which are trying to get to the electrode. This disruption of the diffusion field changes the current response of the electrode. The presence of the sphere is detectable up to a distance of 0.5 mm from the electrode.
The sphere was put into many different positions and the corresponding current response curves of the electrodes were recorded. At the same time, the researchers documented the corresponding positions of the spheres with video. This allowed them to calibrate their measurements so that the position of the spheres could be determined by means of the current response curves of the electrodes.
The researchers would now like to reduce the scale of their technique. They are developing electrode arrays for a spatial resolution at the submicrometer level, which would also allow them to follow significantly smaller particles with sub-microsecond resolution.
Author: Richard G. Compton, University of Oxford (UK), http://compton.chem.ox.ac.uk/contact/contact.htm
Title: A Method for the Positioning and Tracking of Small Moving Particles
Angewandte Chemie International Edition 2009, 48, No. 13, 2376–2378, doi: 10.1002/anie.200805428
BigH1 -- The key histone for male fertility
14.12.2017 | Institute for Research in Biomedicine (IRB Barcelona)
Guardians of the Gate
14.12.2017 | Max-Planck-Institut für Biochemie
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences