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Updated: Feb 9, 2026

Optical Trapping of Plasmonic Nanoparticles for In Situ Surface-Enhanced Raman Spectroscopy Characterizations
Published on: June 23, 2022
Dielectrophoretic Nanoparticle Aggregation for On-Demand Surface Enhanced Raman Spectroscopy Analysis
Reza Salemmilani1, Brian D Piorek1, Rustin Y Mirsafavi2
1Department of Mechanical Engineering , University of California Santa Barbara , Santa Barbara , California 93106 , United States.
Abstract:
Rapid chemical identification of drugs of abuse in biological fluids such as saliva is of growing interest in healthcare and law enforcement. Accordingly, a label-free detection platform that accepts biological fluid samples is of great practical value. We report a microfluidics-based dielectrophoresis-induced surface enhanced Raman spectroscopy (SERS) device, which is capable of detecting physiologically relevant concentrations of methamphetamine in saliva in under 2 min. In this device, iodide-modified silver nanoparticles are trapped and released on-demand using electrodes integrated in a microfluidic channel. Principal component analysis (PCA) is used to reliably distinguish methamphetamine-positive samples from the negative control samples. Passivation of the electrodes and flow channels minimizes microchannel fouling by nanoparticles, which allows the device to be cleared and reused multiple times.
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