The ability to separate cells according to size and shape is useful in biological studies. One popular method of cell sorting involves the use of microfluidic devices consisting of a series of aligned micropillars. Such ‘bump arrays’ operate on the basis of allowing cells that are small enough to pass through narrow gaps, while cells that are too large undergo lateral displacement by bumping into the pillars. Blood samples, for example, can be separated into platelets, white cells and red cells using this technique. However, some particles that have deformable as opposed to rigid structures are prone to becoming ‘mis-sorted’, as they can bypass normal routes through the devices (see image).
Deformable cells can squeeze between narrow gaps in a bump array of micropillars, leading to unpredictable paths in cell sorting devices
Copyright : A*STAR
Keng Hwee Chiam and co-workers at the A*STAR Institute of High Performance Computing have now completed a numerical study modeling ‘dispersive’ routes made in microfluidic devices by deformable particles1. “We wanted to arrive at an understanding of how cell deformability affects the device geometry and functioning, and hence help other researchers to optimize their devices in the future,” says Chiam.
The researchers created a two-dimensional computer model to examine the different possible routes taken by cells through the device pillars. In experimental observations, rigid cells either follow a zigzag pattern through the pillars, or they bump into the pillars and drop to the bottom of the array, depending on their size. The new computer model can accurately predict these paths.
In addition, the model can predict paths taken by large cells or particles that can change shape and squeeze through the pillars. These were found to follow a far more random path, sometimes moving in zigzag directions, sometimes bumping into the pillars, and sometimes getting stuck completely. These so-called ‘dispersive trajectories’ are dependent on the orientation, arrangement and size of the pillars present in the device. Chiam explains, “This shows us what design parameters to avoid, and we imagine that numerical simulations, such as the ones used by the aerospace industry in aircraft design, could benefit future biological technologies.”
The simulations could be improved by extending the computer model to a full three-dimensional representation of the cells and micropillars, but amassing the computational data required is currently cost-prohibitive. Chiam hopes, however, that future collaborations will lead to a three-dimensional version of the model and adds that the research team aims “to simulate the sorting of DNA strands instead of cells, to see if they can be sorted according to their length and sequence.”
The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing
Quek, R., Le, D. V. & Chiam, K.-H. Separation of deformable particles in deterministic lateral displacement devices. Physical Review E 83, 056301 (2011).
New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State
Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Power and Electrical Engineering
25.09.2017 | Health and Medicine
25.09.2017 | Physics and Astronomy