Fischell Department of Bioengineering
Affiliate, Institute for Systems Research
As a bio/chemical sensing technique, surface enhanced Raman spectroscopy (SERS) offers sensitivity comparable to that of fluorescence detection while providing highly specific information about the analyte. The high sensitivity of SERS detection results from the localized plasmons generated at the surface of noble metal nanostructures upon excitation by resonant electric fields at optical frequencies. Although single molecule identification with SERS was demonstrated over a decade ago, today a need exists to develop practical solutions for point-of-sample and point-of-care SERS systems. In recent years, optofluidic SERS has emerged, in which microfluidic functions are integrated to improve the performance of SERS. Advancements in optofluidic SERS are leading towards portable analytical systems, but the devices are currently too expensive and too cumbersome for limited resource settings. Recently, we demonstrated the fabrication of SERS substrates by inkjet printing silver and gold nanostructures onto paper. Using a low-cost commercial inkjet printer, we printed silver nanoparticles with micro-scale precision to form SERS-active biosensors. Using these devices, we have been able to achieve detection limits comparable to conventional nanofabricated substrates. Furthermore, we leverage the fluidic properties of paper to enhance the performance of the SERS devices while also enabling unprecedented ease of use. Paper dipsticks concentrate a relatively large sample volume into a small SERS-active detection region at the tip. Likewise, paper swabs collect samples from a large surface area and concentrate the collected molecules into a SERS sensor on the paper. In addition, the inherent chromatographic properties of paper enable sample cleanup and analyte separation to improve detection in complex real-world samples.
In this seminar, we will review the capabilities of SERS as a chemical and biological sensing technique. We will then present an overview of optofluidic SERS and its potential as a point-of-sample and point-of-care analytical technique. Next we will summarize the progress in the fabrication and use of paper-based fluidic devices for SERS-based detection, and we will describe their use in practical applications for point-of-sample chemical detection. Finally, we will discuss applications in highly sensitive point-of-care biological sensing for diagnostics that are currently under development.
Ian White is an Assistant Professor in the Fischell Department of Bioengineering at the University of Maryland. Dr. White received his Ph.D. in Electrical Engineering from Stanford University in 2002, where he developed next generation optical metropolitan area networks. He then served as a Member of Technical Staff at Sprint's Advanced Technology Laboratories until 2005. At that time, Dr. White transitioned into the field of optical biosensors as a Postdoctoral Fellow in the University of Missouri Life Sciences Center. In 2008, Dr. White joined the faculty in the Fischell Department of Bioengineering at the University of Maryland. His research group aims to develop novel microsystems for applications in chemical analytics and disease diagnosis.