Droplet-based Liquid-Liquid Extraction and On-Chip IR-Waveguide-Spectroscopy Detection of Cocaine in Human Saliva

We present a portable microsystem to quantitatively detect cocaine in human saliva. The chip combines a simple microfluidic method for multiphase liquid-liquid extraction to transfer cocaine from IR-light absorbing saliva to an IRtransparent solvent with the on-chip cocaine detection by IR-waveguide-spectroscopy (QC-laser, waveguide, detector). With our droplet-based extraction method we achieve an additional analyte pre-concentration of at least two orders of magnitude.