Technology
Design and fabrication of sensor structures, deposition of nano-layers, measurements of material and its functional parameters.
Sensors
Based on the advanced equipment available in our laboratories and many years of technological and measurement experience, we produce optical sensors which are a very diverse group of transmission and reflection structures. In our works, we use, among others thin-film technologies, laser ablation (nano- and femtosecond), electric arc glass welding, mechanical surface modification techniques, and nanoimprinting.
In most cases, the sensors are based on optical fibers and are dedicated to the detection of chemical compounds or biological structures. The technological modifications of the optical fiber carried out as part of our work are aimed at enabling the interaction of the electromagnetic wave propagating in the fiber with the tested substance. As a result of these interactions, the conditions of wave propagation inside the fiber change in a controlled manner, which is reflected in the changes in the transmitted or reflected optical spectrum. Simultaneous spectrum analysis enables real-time observations of changes in the tested analyte or, after functionalisation of the sensor surface, for a marker-free detection of specific biological structures. The fiber-optic sensors studied by us include, among others, structures based on the effect of lossy mode resonance (LMR), surface plasmon resonance (SPR), Mach-Zender microinterferometers, Fabry-Perot microinterferometers or meshes diffractive, including long-term.
Nanolayers
As part of our work, the structure of the optical fiber is most often modified by applying a thin layer of material (from a few to several hundred nanometers) to the surface of the optical fiber in a highly controlled manner. The presence of the layer allows to obtain a specific optical effect (usually resonance) and to optimize the sensitivity. In our laboratories, thin layers are obtained by magnetron sputtering, plasma enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD). The thin films we manufacture include, among others, carbon materials, compounds of titanium, aluminum, hafnium, tin, indium, tantalum, zirconium, zinc and silicon. We embed metals, dielectrics and semiconductors, also in the form of multi-layer systems with a highly controlled structure. Metals and semiconductors, apart from obtaining optical interactions, also allow the integration of electrical and electrochemical measurements within one sensor.
Layer parameters
Verification of the optical properties and thickness of the deposited nano-layers is a key task, as most often it is these parameters that determine the functionality of optical sensors. We characterize nanolayers using spectroscopic ellipsometry or contact profilometry. Additionally, visual observation of the produced structures directly on the optical fiber is possible using a confocal microscope or a scanning electron microscope (SEM).
Initial characterization and calibration of the resulting sensors for further biosensory applications is carried out with the use of broadband light sources (including supercontinuum) as well as spectrometers and broadband spectrum analyzers. In dedicated measurements of optical paths and sensor systems, apart from optical fibers, we also use a number of other elements such as filters, collimators, polarizers, etc.
Simulations
Fiber-optic sensors developed in our laboratories are innovative solutions not available on the commercial market. One of the challenges is to create numerical models describing the behavior of electromagnetic waves in unconventional optical fiber structures. We use the experimental results obtained during the characterization to create and develop numerical models, on the basis of which we can optimize the parameters of the structures produced, but also predict the response of sensors under various conditions.
