Using Silver to Enhance Spectroscopic Signals of Bacteria
Standing
Undergraduate
Type of Proposal
Oral Research Presentation
Challenges Theme
Open Challenge
Faculty Sponsor
Dr. Steven Rehse
Proposal
Laser induced breakdown spectroscopy (LIBS) is a technique in which a laser pulse is focused on a target to produce a plasma. As the plasma cools, it emits light to be collected by a spectrometer to determine the elemental composition of the target. We use LIBS to rapidly identify and classify bacterial pathogens with an end goal of using our methods for diagnosis of bacterial infections in clinical applications. I have worked to enhance the bacterial LIBS emission spectra using silver. A 60 mJ 1064 nm pulsed laser was focused onto a rotating silver foil target in a vacuum chamber to sputter a highly uniform silver thin film onto a nitrocellulose filter. Sputtering times from 1 minute to 20 minutes were investigated. Uniformity was determined with LIBS and a scanning electron microscope. The silver filters were removed from the vacuum sputtering chamber, bacteria were deposited, and the deposition was ablated to acquire LIBS spectra. Analysis of these spectra showed a 50-100% increase in the ion emission intensity and a decrease in neutral element emission intensity, indicating an increase in plasma temperature. While overall LIBS emission enhancement was observed for a sample deposited on a silver filter compared to an empty filter for sputtering times greater than 15 minutes, this increase was not statistically significant. Work is ongoing to produce nanoparticle solutions using pulsed laser ablation in water to give statistically significant enhancement of the bacterial emission spectra using silver nanoparticles instead of a silver thin film.
Grand Challenges
Viable, Healthy and Safe Communities
Using Silver to Enhance Spectroscopic Signals of Bacteria
Laser induced breakdown spectroscopy (LIBS) is a technique in which a laser pulse is focused on a target to produce a plasma. As the plasma cools, it emits light to be collected by a spectrometer to determine the elemental composition of the target. We use LIBS to rapidly identify and classify bacterial pathogens with an end goal of using our methods for diagnosis of bacterial infections in clinical applications. I have worked to enhance the bacterial LIBS emission spectra using silver. A 60 mJ 1064 nm pulsed laser was focused onto a rotating silver foil target in a vacuum chamber to sputter a highly uniform silver thin film onto a nitrocellulose filter. Sputtering times from 1 minute to 20 minutes were investigated. Uniformity was determined with LIBS and a scanning electron microscope. The silver filters were removed from the vacuum sputtering chamber, bacteria were deposited, and the deposition was ablated to acquire LIBS spectra. Analysis of these spectra showed a 50-100% increase in the ion emission intensity and a decrease in neutral element emission intensity, indicating an increase in plasma temperature. While overall LIBS emission enhancement was observed for a sample deposited on a silver filter compared to an empty filter for sputtering times greater than 15 minutes, this increase was not statistically significant. Work is ongoing to produce nanoparticle solutions using pulsed laser ablation in water to give statistically significant enhancement of the bacterial emission spectra using silver nanoparticles instead of a silver thin film.