Project

Detection of drugs of abuse, particularly methamphetamine, in a fast and reliable way would have great benefits to law enforcement and health care. In collaboration between the Meinhart Lab in Mechanical Engineering and the Moskovits Lab in Chemistry, a microfluidic device that detects trace concentrations of methamphetamine in saliva within minutes and with minimal sample volume was developed. This project combines microfluidics and surface enhanced Raman spectroscopy (SERS), a powerful spectroscopic technique that provides unique spectral signatures for different chemicals.

The microfluidic device focuses the saliva sample between two sheathing flows, and extracts small molecules (such as methamphetamine) by diffusion. Simultaneously, the sample interacts with silver nanoparticles that, when excited by a laser, demonstrate the plasmonic resonance necessary for SERS.

By adjusting the flow rate in the device and the salinity of the buffers used, we can tailor the nanoparticle aggregation within the device to ensure reproducible SERS signal independent of the sample.

This work spanned across the CNSI Core Labs. Nanoparticle characterization techniques (e.g. absorption spectroscopy, zeta-potential) available at the BNL were used to determine the aggregation rates of our silver nanoparticles. A numerical model for the system was developed and simulated using a CSC computer cluster. The device molds were fabricated in the NCF and the devices were used for the experiments in the Microfluidics Lab.

Publications