Photonic biosensor for lab-on-a-chip applications

Stefanie Demming, Andreu Llobera, Victor Javier Cadarso, Jahir Orozco, Cesar Fernàndez-Sànchez, Ralph Wilke, Stephanus Büttgenbach

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review


We have developed a monolithically integrated and highly sensitive polydimethylsiloxane (PDMS) based biosensor that includes microfluidics and photonics in a single-mask process. Optically, the system consists of selfalignment structures for fiber optics positioning, microlenses (to correct the divergence of the emitted light) and air micromirrors (to improve the reflection of the propagating light). Two air mirrors are integrated within the system. Knowing the refractive index difference between air and PDMS, the design of such mirrors is done so as to assure that light fulfills the total internal reflection (TIR) conditions and thus, light propagates through the fluidic bioreactor chamber following a zig-zag path. The highly sensitive performance of this biosensor was firstly validated by measuring the absorbance as a function of fluorescein concentration: Fluorescein labeling is often used to mark cells, organelles or molecules with known specificity and is therefore important for online analysis in biotechnological processes. In the photonic biosensor we obtained an LOD of 0.110±0.002 μM proving the capability of highly sensitive measurements. As a second biotechnological application the optical determination of H2O2 concentration was measured. H 2O2 is the product in enzymatic reactions of biotechnological relevant metabolites such as glucose and ethanol. Via catalytic reduction - provided by covalently immobilized horseradish peroxidase (HRP, type VI) - H2O2 is converted to H2O with the concomitant oxidation of 2,2'-azino-bis(3- ethylbenzthiazoline-6-sulfonic acid) (ABTS) to the greencolored cation radical ABTS+. This resulting difference in absorbance was analyzed for various H2O2 concentrations achieving an LOD of 2.8±0.4 μM.

Original languageEnglish
Title of host publication10th International Symposium on Measurement and Quality Control 2010, ISMQC 2010
Number of pages4
Publication statusPublished - 2010
Externally publishedYes
Event10th International Symposium on Measurement and Quality Control 2010, ISMQC 2010 - Osaka, Japan
Duration: 5 Sept 20109 Sept 2010


Conference10th International Symposium on Measurement and Quality Control 2010, ISMQC 2010


  • Biological measurement
  • Biosensor
  • Photonic lab-on-a-chip
  • Polydimethylsiloxane

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