A research team led by Oak Ridge National Laboratory’s Panos Datskos is developing a chemical and biological sensor with unprecedented sensitivity. Ultimately, researchers believe this new “sniffer” will achieve a detection level that approaches the theoretical limit for detecting explosives, biological agents, and narcotics. The device consists of a digital camera, a laser, imaging optics, a signal generator, and digital signal processing. Collectively, these components can detect tiny amounts of substances in the air — much like a dog’s nose. The underlying concept is based on micro-scale resonators similar to the microcantilevers used in atomic force microscopy. Although the basic principle is simple — measuring changes in the resonance frequency due to mass changes — a number of obstacles have impeded widespread application of such systems.
“These challenges are due to requirements of measuring and analyzing tiny oscillation amplitudes that are about the size of a hydrogen atom,” explains co-developer Nickolay Lavrik, a member of the Department of Energy lab’s Center for Nanophase Materials Sciences Division. Such traditional approaches require sophisticated low-noise electronic components such as lock-in amplifiers and phase-locked loops, which add cost and complexity. The new type of sniffer works by deliberately hitting the microcantilevers with relatively large amounts of energy associated with a range of frequencies, forcing them into wide oscillation, or movement. Lavrik likens the response to a diving board’s movement after a swimmer dives. “In the past, people wanted to avoid this high amplitude because of the high distortion associated with that type of response,” adds Datskos, a member of the Measurement Science and Systems Engineering Division. “Now we can exploit that response by tuning the system to a very specific frequency that is associated with the specific chemical or compound we want to detect.” The researchers expect the technology to be incorporated into a handheld instrument that could be used by transportation security screeners, law enforcement officials, and military personnel, with additional applications in biomedicine, environmental science, homeland security, and analytical chemistry. A prototype could be available in six to 18 months.
Source: Chemical Online