Investigation of thin polymer layers for biosensor applications

András Saftics, Emil Agócs, Bálint Fodor, Dániel Patkó, Péter Petrik, Kai Kolari, Timo Aalto, Péter Fürjes, Robert Horvath, Sándor Kurunczi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Novel biosensors made of polymers may offer advantages over conventional technology such as possibility of mass production and tunability of the material properties. With the ongoing work on the polymer photonic chip fabrication in our project, simple model samples were tested parallel for future immobilization and accessing conditions for applications in typical aqueous buffers. The model samples consist of a thin, high refractive index polyimide film on top of TEOS on Si wafer. These model samples were measured by in situ spectroscopic ellipsometry using different aqueous buffers. The experiments revealed a high drift in aqueous solutions; the drift in the ellipsometric parameters (delta, psi) can be evaluated and presented as changes in thickness and refractive index of the polyimide layer. The first molecular layer of immobilization is based on polyethyleneimine (PEI). The signal for the PEI adsorption was detected on a stable baseline, only after a long conditioning. The stability of polyimide films in aqueous buffer solutions should be improved toward the real biosensor application. Preliminary results are shown on the possibilities to protect the polyimide. Optical Waveguide Lightmode Spectroscopy (OWLS) has been used to demonstrate the shielding effect of the thin TiO 2 adlayer in biosensor applications.

Original languageEnglish
Pages (from-to)66-72
Number of pages7
JournalApplied Surface Science
Volume281
DOIs
Publication statusPublished - Sep 15 2013

Keywords

  • Drift
  • In situ ellipsometry
  • Optical properties
  • Photonic biosensor
  • Polyimide
  • Polymer

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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