Label-free Detection Methods


Reflectometric Interference Spectroscopy (RIfS)

Reflectometric Interference Spectroscopy (RIfS) is a label-free detection method based on multiple reflexion of white light at thin interfaces (white light interferometry according to FABRY-PEROT). Interactions at solid surfaces can be observed using time-resolved methods; the aim is to detemine thermodynamic and kinetic constants of these processes.



Surface Plasmon Resonance (SPR)

Detection of molecular interaction is realised through excitaton of surface plasmons using parallel-polarised light. This method allows the monitoring of changes in the effective refractive index of recognition structures.



Mach-Zehnder Interferometry

A coherent beam is split into two arms using a beamsplitter.The Mach-Zehnder interferometer is used to determine the phase shift caused by a small sample placed into one of the two beams. The difference in refractive indices is caused by the analyte binding to a sensitive surface which covers only one arm of the Mach-Zehnder interferometer.



Grating Coupler

Grating couplers can be used to determine the refraction index using an evanescent field. The refraction index affects the grating constant and thus the influences the interference properties of the electromagnetic light.



Infrared Spectroscopy (IR)

Infrared spectroscopy (IR Spectroscopy) is a type of absorption spectroscopy using the infrared part of the electromagnetic spectrum. This method can be used to investigate the composition of samples.