Integrated Optics and Sensors

B. Menges

The micro- and macroscopic characterisation of polymers is of special interest. Resonant evanescent optical methods with their local field enhancement are particularly suitable for the investigation of supramolecular architectures on surfaces. Surface plasmon resonance spectroscopy (SPR) and waveguide spectroscopy (WaMS) are established methods for the determination of optical and structural parameters. The combination of these methods with other established techniques such as the quartz crystal microbalance with dissipation (QCM-D) offers the possibility of a better and more comprehensive characterisation. Shallow diffraction gratings are an elegant possibility for the excitation of surface bound electromagnetic waves in integrated optics devices.

left : Combined experimental design for surface plasmon excitation via shallow diffraction grating on a quartz crystal sensor. right : Quartz crystal sensor with shallow diffraction grating for surface plasmon excitation.

For instance vesicle fusion has been studied by combining these two techniques, both are mass sensitive, but rely on different physical principles. SPR spectroscopy is an optical technique that only measures the ‘’dry’’ mass of the film and the optical film thickness. QCM-D is an acoustic technique that detects the resonance frequencies of a film deposited on the surface of a quartz crystal sensor. Information about the mass and the viscosity of the film is then obtained. In QCM-D, the frequency is a measurement of the mass of the film and includes any coupled water. The combination can provide valuable information concerning the water content and its role in the film structure. Since these measurements were taken simultaneously from the same surface, studying kinetic process also during the formation of this system and comparing both SPR spectroscopy and QCM-D is possible.

left & right: Vesicle fusion on a self assembled monolayer. Resulting in the formation of a rigid lipid bilayer membrane

Silvia Mittler and Bernhard Menges, Evanescent waves as nanoprobes for surfaces and interfaces: from waveguide technology to sensor application, To be submitted to: Surface Nanophotonics. Principles and Applications, Ed. Andrews and Gaburro. Springer-Verlag, New York (2005)
Alexander Laschitsch, Bernhard Menges and Diethelm Johannsmann. Simultaneous determination of optical and acoustic thickness of protein layers using surface plasmon resonance spectroscopy and quartz crystal microweighing, Appl. Phys. Lett., Vol. 77, No. 14, 2000, 2252- 2254
Larry E. Bailey, Kay K. Kanazawa, Gandharv Bhatara, George W. Tyndall, Max Kreiter, Wolfgang Knoll and Curtis W. Frank. Multistep Adsorption of Perfluoropolyether Hard-Disk Lubricants onto Amorphous Carbon Substrates from Solution, Langmuir 17, 2001, 8145-8155