Better Detection for Diagnostics and Biochemical Defense

ScienceDaily (Oct. 29, 2010) — Current detection methods for chemical and biological molecules involve using tiny, molecular "labels," typically fluorescent or radioactive entities, which can be a time-consuming and expensive process. A University of Michigan research team headed by Associate Professor Xudong (Sherman) Fan, recently developed a system for detecting chemical and biological molecules without labels, and they expect the technology to have broad applications ranging from clinical diagnostics to drug development, as well as homeland security and environmental monitoring for biological and chemical weapons.

According to Fan, the new method has the additional benefit of not altering the molecules of interest. "We just measure the molecules directly," he says, adding that labeling "is a time-consuming and costly process... and may affect the biological functions of the molecule" being examined.
Fan and his colleagues built their system by adapting an optical sensing device known as a ring resonator, which has greater sensitivity than traditional optical fiber or waveguide sensors. The team partnered the ring device with a capillary-based fluidic system, creating a "unique integration of capillary fluidics with ring resonator technology," according to Fan.
The capillary system can be used for the introduction of either liquid or gas to the sensor, giving the new device a broad spectrum of potential applications. In a clinical diagnostic setting, for example, body fluids such as blood and saliva can be used. Alternatively, vapor analysis can also be performed on exhaled breath for early and non-invasive diagnosis of diseases such as cancers. For homeland security and environmental monitoring purposes, volatile organic compounds, such as explosives, are typically of interest. Particularly for gaseous compounds, most current systems suffer from a lack of specificity. The combined device developed by Fan's group, however, can be built into a so-called "micro GC" (gas chromatography), which enables highly specific identification of compounds.
The talk, "Optical Ring Resonator Based Biological and Chemical Sensors," took place on Oct. 26 at the Frontiers in Optics (FiO) 2010/Laser Science XXVI -- the 94th annual meeting of the Optical Society (OSA), which was held together with the annual meeting of the American Physical Society (APS) Division of Laser Science at the Rochester Riverside Convention Center in Rochester, N.Y., from Oct. 24-28.