title: Detection of Dissolved Lactose Employing an Optofluidic Micro-System.
abstract: In this work, a novel optofluidic sensor principle is employed for a non-invasive and label-free characterization of lactose containing liquid samples. Especially for medicine and food industry, a simple, fast and accurate determination of the amount of lactose in various products is highly desirable. The presented system exploits the impact of dissolved molecules on the refractive index for sample characterization. On the optofluidic chip, a microfluidic channel filled with the analyte is hit by slightly diverging laser light. The center incident angle of the beam on-chip is set close to the critical angle for total internal reflection. Both the reflected and the transmitted light signals are recorded at the solid-liquid interface. The ratio of those two signals is then used as representative value for the analyte. Using this principle, lactose containing samples were differentiated based on their concentrations at a step size of 10 mmol/L. The use of the signals ratio instead of a single signal approach improves the stability of the system significantly, allowing for higher resolutions to be achieved. Furthermore, the fabrication of the devices in PDMS ensures biocompatibility and provides low absorbance of light in the visible range.
authors: Institute for Microsensors, Actuators and Systems (IMSAS), Microsystems Center Bremen (MCB), University of Bremen, Otto-Hahn-Allee NW1, 28359 Bremen, Germany. eweber@imsas.uni-bremen.de.
authors: Emanuel
authors: E
authors: Weber
authors: Institute of Sensor and Actuator Systems, Vienna University of Technology, Gusshausstrasse 27-29,E366, 1040 Vienna, Austria. franz.keplinger@tuwien.ac.at.
authors: Franz
authors: F
authors: Keplinger
authors: Institute for Microsensors, Actuators and Systems (IMSAS), Microsystems Center Bremen (MCB), University of Bremen, Otto-Hahn-Allee NW1, 28359 Bremen, Germany. mvellekoop@imsas.uni-bremen.de.
authors: Michael J
authors: MJ
authors: Vellekoop
keywords: label-free; lactose detection; non-invasive; optofluidics; partial total internal reflection