title: An in-line photonic biosensor for monitoring of glucose concentrations.
abstract: This paper presents two PDMS photonic biosensor designs that can be used for continuous monitoring of glucose concentrations. The first design, the internally immobilized sensor, consists of a reactor chamber, micro-lenses and self-alignment structures for fiber optics positioning. This sensor design allows optical detection of glucose concentrations under continuous glucose flow conditions of 33 µL/h based on internal co-immobilization of glucose oxidase (GOX) and horseradish peroxidase (HRP) on the internal PDMS surface of the reactor chamber. For this design, two co-immobilization methods, the simple adsorption and the covalent binding (PEG) methods were tested. Experiments showed successful results when using the covalent binding (PEG) method, where glucose concentrations up to 5 mM with a coefficient of determination (R2) of 0.99 and a limit of detection of 0.26 mM are detectable. The second design is a modified version of the internally immobilized sensor, where a microbead chamber and a beads filling channel are integrated into the sensor. This modification enabled external co-immobilization of enzymes covalently onto functionalized silica microbeads and allows binding a huge amount of HRP and GOX enzymes on the microbeads surfaces which increases the interaction area between immobilized enzymes and the analyte. This has a positive effect on the amount and rate of chemical reactions taking place inside the chamber. The sensor was tested under continuous glucose flow conditions and was found to be able to detect glucose concentrations up to 10 mM with R2 of 0.98 and a limit of detection of 0.7 mM. Such results are very promising for the application in photonic LOC systems used for online analysis.
authors.affiliation: Institute of Microtechnology, Technische Universität Braunschweig, Langer Kamp 8, 38106 Braunschweig, Germany. Alaaldeen.Alhalhoul@gju.edu.jo.
authors.forename: Ala'aldeen
authors.initials: A
authors.lastname: Al-Halhouli
authors.affiliation: Institute of Microtechnology, Technische Universität Braunschweig, Langer Kamp 8, 38106 Braunschweig, Germany. stefanie.demming@googlemail.com.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Demming
authors.affiliation: Institute of Microtechnology, Technische Universität Braunschweig, Langer Kamp 8, 38106 Braunschweig, Germany. lailadtr@yahoo.com.
authors.forename: Laila
authors.initials: L
authors.lastname: Alahmad
authors.affiliation: CentreNacional de Microelectrònica (IMB-CNM, CSIC), 08193 Barcelona, Spain. andreu.llobera@imb-cnm.csic.es.
authors.forename: Andreu
authors.initials: A
authors.lastname: LIobera
authors.affiliation: Institute of Microtechnology, Technische Universität Braunschweig, Langer Kamp 8, 38106 Braunschweig, Germany. s.buettgenbach@tu-bs.de.
authors.forename: Stephanus
authors.initials: S
authors.lastname: Büttgenbach
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D004129:Dimethylpolysiloxanes; D004800:Enzymes, Immobilized; C013830:baysilon; D005949:Glucose Oxidase; D006735:Horseradish Peroxidase; D005947:Glucose