Electromagnetic miniatures

October 06, 2006

Magnetic components that can be controlled by the application of an external electric field are useful in many different applications. They can serve as microfluidic pumps, mixers, or valves in miniature lab-on-chip systems, or they can help in sorting and arranging magnetic particles. Biochemistry and cellular biology in particular benefit from many possible uses: for example, antibodies or other ligands that bind to individual biomolecules or to surface structures of cells can be coupled to magnetic beads in order to recognize and bind to their specific bonding partner even in complex mixtures. They can subsequently be fished out of the mixture with an electromagnet. Electromagnets have an additional advantage over permanent magnets: they can easily be switched on and off with an electric current. Also, the field strength can be adjusted to the desired value and can be changed as required. However, electromagnets do have the disadvantage of generating weaker magnetic fields, meaning that they must be very close to the place where they are to be used.

G. M. Whitesides and his co-workers at Harvard University in Cambridge, USA, have now developed an uncomplicated method for producing a microfluidic channel along with two metal cables parallel to it and only 10 μm away. First, a structure consisting of a 40-μm-wide and 40-μm-deep inner channel between two 120-μm-wide and 40-μm-deep outer channels was lithographically engraved into a polydimethylsiloxane resin. Treatment with 3-mercaptopropyltrimethoxysilane silanized the surfaces of the outer channels. This allowed them to be coated with molten solder that was poured into the heated forms in the next step. Upon cooling, the liquid metal solidified, forming two stable metal cables to the left and right of the inner channel. Application of an electrical field to these two wires generates magnetic fields of up to 2.8 mT within the central channel.

It was also possible to steer magnetic spheres through the channel: the scientists again made a channel with parallel wires on either side, but this time the channel forked after a few millimeters. A suspension of magnetic spheres flowed through the channel. If current was allowed to flow through wire on the right, the spheres flowed to the right as they reached the fork, and vice versa.
Author: George M. Whitesides, Harvard University, Cambridge (USA), http://gmwgroup.harvard.edu/contact.html
Title: Cofabrication of Electromagnets and Microfluidic Systems in Poly(dimethylsiloxane)
Angewandte Chemie International Edition 2006, 45, No. 41, 6877-6882, doi: 10.1002/anie.200602273


Related Biochemistry Articles from Brightsurf:

Removing belly fat before it sticks to you
University of Cincinnati researchers are producing in the lab a human protein tasked with removing triglycerides from the blood stream.

How tiny enzymes reign supreme in worldwide carbon recycling
That white rot fungi on fallen logs in a forest, it's super important.

Researchers uncover critical metabolic switch for inflammatory diseases
A research team in Trinity College Dublin has uncovered a critical role for a protein called 'PKM2' in the regulation of immune cell types at the heart of multiple inflammatory diseases.

Enzyme helps build motor that drives neuron death
The process, discovered in the axons of neurons, is implicated in Alzheimer's, amyotrophic lateral sclerosis, traumatic brain injury and other diseases or injuries to the nervous system.

Fat cell filling, ketogenic diet, and the history of biochemistry:
Recent articles in the Journal of Lipid Research investigate how brown fat converts to white, how cells in the liver fill fat droplets, and how eating a ketogenic or calorie-restricted diet may change a mouse's metabolism.

New device uses biochemistry techniques to detect rare radioactive decays
UTA researchers are now taking advantage of a biochemistry technique that uses fluorescence to detect ions to identify the product of a radioactive decay called neutrinoless double-beta decay that would demonstrate that the neutrino is its own antiparticle.

ALS-linked protein's journey into nervous system cells more complex than we thought
University of Bath scientists have developed a better understanding of a key protein associated with brain diseases including ALS (motor neurone disease) and dementia by studying how it enters central nervous system cells.

New assay leads to step toward gene therapy for deaf patients
Scientists at have taken an important step toward gene therapy for deaf patients by developing a way to better study a large protein essential for hearing and finding a truncated version of it.

Virginia Tech biochemists dip into the health benefits of olives and olive oil
Virginia Tech research team discovered that the olive-derived compound oleuropein helps prevent type 2 diabetes.

Aussie quantum tech has its sights set on human biochemistry
Australian scientists have developed a new tool for imaging life at the nanoscale that will provide new insights into the role of transition metal ions such as copper in neurodegenerative diseases.

Read More: Biochemistry News and Biochemistry Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.