Magnetic Nanobeads Could Polish Off Rust from Microfluidic Sensors

Researchers at Oregon State University (OSU; Corvallis) have discovered how to use magnetic 'nanobeads' to help detect chemical and biological agents. When it is developed into a handheld sensor, this microfluidic sensor technology could benefit a range of applications, including portable diagnostic devices.

The key to the technology is minuscule pieces of rust composed of ferromagnetic iron oxide nanoparticles. While these particles can selectively detect chemicals, they can also be incorporated into a system of integrated circuits to instantly display the findings.

"The particles we're using are 1000 times smaller than those now being used in common diagnostic tests, allowing a device to be portable and used in the field," remarks Vincent Remcho, a professor of chemistry and associate dean for research and graduate programs in the OSU College of Science. "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."

This technology, according to Pallavi Dhagat, an assistant professor in the OSU school of electrical engineering and computer science, should result in a powerful sensing technology that is fast, accurate, inexpensive, mass-producible, and small enough to hold in your hand.

Existing assays are often cumbersome and time consuming, using biochemical probes that require expensive equipment, expert personnel, or a complex laboratory to detect or interpret. The OSU scientists' approach, in contrast, involves attaching nanoparticles to these biochemical probes. When a chemical of interest is detected, a ferromagnetic resonance relays the information electronically to a tiny computer, which displays the information to the user. Although no special thin films or complex processing steps are required, the sensor's detection capability is sensitive and accurate.

Potentially capable of detecting almost anything of interest in air or water, the technology also has "green" benefits, the scientists say. The use of rusty iron should help address issues of safety in the resulting product.