Microfluidic droplet-based liquid–liquid extraction and on-chip IR spectroscopy detection of cocaine in human saliva

Wägli, Philip (Sensors, Actuators and Microsystems Laboratory, Institute of Microengineering, EPFL, Lausanne, Switzerland) ; Chang, Yu-Chi (Optics & Photonics Technology Laboratory, Institue of Microengineering, EPFL, Lausanne, Switzerland) ; Kämpfer-Homsy, Alexandra (Sensors, Actuators and Microsystems Laboratory, Institute of Microengineering, EPFL, Lausanne, Switzerland ; School of Engineering – HE-Arc Ingénierie, HES-SO // University of Applied Sciences Western Switzerland) ; Hvozdara, Lubos (Optics & Photonics Technology Laboratory, Institue of Microengineering, EPFL, Lausanne, Switzerland) ; Herzig, Hans Peter (Optics & Photonics Technology Laboratory, Institue of Microengineering, EPFL, Lausanne, Switzerland) ; de Rooij, Nico F. (Sensors, Actuators and Microsystems Laboratory, Institute of Microengineering, EPFL, Lausanne, Switzerland)

We present a portable microsystem to quantitatively detect cocaine in human saliva. In this system, we combine a microfluidic-based multiphase liquid–liquid extraction method to transfer cocaine continuously from IR-light-absorbing saliva to an IR-transparent solvent (tetrachloroethylene) with waveguide IR spectroscopy (QC-laser, waveguide, detector) to detect the cocaine on-chip. For the fabrication of the low-cost polymer microfluidic chips a simple rapid prototyping technique based on Scotch-tape masters was further developed and applied. To perform the droplet-based liquid–liquid extraction, we designed and integrated a simple and robust droplet generation method based on the capillary focusing effect within the device. Compared to well-characterized and commonly used microfluidic H-filters, our system showed at least two times higher extraction efficiencies with potential for further improvements. The current liquid–liquid extraction method alone can efficiently extract cocaine and pre-concentrate the analytes in a new solvent. Our fully integrated optofluidic system successfully detected cocaine in real saliva samples spiked with the drug (500 μg/mL) and allowed real time measurements, which makes this approach suitable for point-of-care applications.


Keywords:
Article Type:
scientifique
Faculty:
Ingénierie et Architecture
School:
HE-Arc Ingénierie
Institute:
Aucun institut
Date:
2013-07
Pagination:
8 p.
Published in:
Analytical Chemistry
Numeration (vol. no.):
2013, vol. 85, no. 15, pp. 7558-7565
DOI:
ISSN:
0003-2700
Appears in Collection:



 Record created 2020-06-30, last modified 2020-10-27


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