Handheld biosensors and diagnostic devices could be taking a huge step forward, thanks to recent advances made in the use of ferromagnetic iron oxide nanoparticles – also known as magnetic nanobeads. According to scientists from Oregon State University (OSU), the use of such particles in chemical detection systems could make those systems much smaller, faster, cheaper to produce, and more accurate than they are presently.

Current microfluidic chemical assay systems utilize biochemical probes, that the OSU team says "require expensive equipment, expert personnel or a complex laboratory to detect or interpret." In the new system, the ferromagnetic iron oxide nanoparticles (essentially tiny particles of rust) would be attached to those biochemical probes. When specific chemicals were encountered, the resulting "ferromagnetic resonance" of the particles would be electronically relayed to a computer built into the detection device, which would in turn alert its human user to the presence of the chemicals.

The researchers claim that the technology could be used to detect just about anything in air or water, without the need for special thin films or complex processing, while still offering great sensitivity and accuracy.

"The particles we're using are 1,000 times smaller than those now being used in common diagnostic tests, allowing a device to be portable and used in the field," said chemist and study leader Prof. Vincent Remcho. "Just as important, however, is that these nanoparticles are made of iron. Because of that, we can use magnetism and electronics to make them also function as a signaling device, to give us immediate access to the information available."

Applications for nanobead-equipped devices could include antiterrorism, water treatment, environmental monitoring, cargo inspections, biomedical applications in research or medical care, pharmaceutical drug testing, or food safety. The basic concept has been proven in experiments, with the scientists now working on making the technology suitable for extended field use.

The research was recently published in the journal Sensors and Actuators.