Gandolf Feigl

The diagnosis of infectious diseases like sepsis generally requires laboratory analyses, costly equipment, and is time-consuming. A very promising approach for rapid medical testing, potentially even outside of clinics, is the use of waveguide-based evanescent field photonic sensors. The sensor concept relies on the binding of an antigen to an antibody immobilized on the sensor surface, causing a detectable change in the effective refractive index of the waveguide. State-of-the-art photonic sensor systems are typically limited to controlled laboratory environments and expensive benchtop-type tunable lasers, prohibiting widespread use in diagnostics.

The aim of this thesis is the development of a Silicon Nitride based label-free photonic immunosensor platform for point-of-care (PoC) sepsis detection. The system design of an integrated detection platform includes optoelectronics, microfluidics, and signal processing. Emphasis is laid on the development of a robust system concept suitable for cost-effective mass production, enabling rapid testing for PoC applications.

Jakob Hinum-Wagner

In recent years, silicon photonics has developed into a mature technology in the field of Datacom. The integration of a variety of optical and optoelectronic functionalities was enabled by using the possibilities of modern CMOS technology.  Although applications the field telecom and Datacom dominate in the market share, there is nowadays a growing demand also in the term of small scale and highly integrated sensing applications that yearns to fully exploit the possibilities of integrated photonics. To meet the demands in terms of which needed in state of the art sensing technology for health and scientific purposes, a reliable and economically feasible process flow needs to be established.

The first part of this thesis aims at the investigation of an existing SiN waveguide process flow at ams OSRAM. The most important parameters are analysed, which influence waveguide losses, especially the surface roughness of the involved components. The critical steps are identified and unit process development is done on these. In the further course of this thesis a model which connects several roughness parameters with the waveguide loss is developed and compared to measured values. In the final step of this thesis, the gained knowledge is used to improve targeted sensing applications in terms of specificity, signal-to noise-ratio and resolution.

Hafiz Hashim Imtiaz

The poor quality of air still appears as a critical issue concerning the public health. The emissions from on-road vehicles are considered to be the largest contributor to air pollution. The real time monitoring of vehicles in traffic can play a vital role in recognising the high emitters over the road. Some advanced techniques have been developed for the measurement of emissions released from the tailpipe of vehicles. The remote emission sensing (RES) approach is the most economical and highly efficient method due to its ability of screening thousands of on-road vehicles using optical methods.
In this thesis, a state-of-the-art and highly accurate RES system will be developed to identify high emitters on roads. The system will be developed using progressive sensors, state-of-the-art spectroscopic techniques and advanced artificial intelligence and image processing methods. This system will be able to measure the following:

• The Speed and Acceleration of the passing car
• The distance from the passing car
• The size of exhaust emitted from the tailpipe of the passing car
• The registration number of the passing car
• The concentration of pollutants presents in the exhaust emitted from the passing car

All the measurements will be combined using advanced data processing techniques to measure the real-time and highly accurate emissions from the passing vehicles and the high emitters will be easily identified from the moving traffic.

Johannes Mandl

Nowadays, our infrastructure and daily life are highly dependent on the reliability of the electric power system.  Prolonged outages of power, caused by damages to the system’s components, have been identified as serious threats to our society.

One potentially harmful influence on the electrical infrastructure are geomagnetically induced currents (GICs), which arise from solar activity. The interaction of charged particles coming from the sun with the earth’s magnetosphere can induce an electrical field on ground level that causes a quasi direct current in any conducting structure, such as electrical power lines. These unwanted currents affect the functionality and lifetime of power transformers in the electrical grid.

For this reason, a Fiber-Optic sensor based on the Faraday effect is being investigated to measure GICs on high-voltage lines. This type of sensor exhibits favorable properties such as electrical insulation, low weight and no saturation. During this thesis, carried out within the project FORESEEN, several system architectures and signal processing schemes are investigated to detect currents in the range of a few milliamperes on individual phases at operating voltages of the grid from 220 kV to 380 kV, despite superimposition with the 50 Hz AC current. The goal of this work is to build a highly precise sensor prototype with low cost and long-term reliability.

Thomas Neubauer

During certification processes of aircraft for operation under icing conditions, tests are performed in specially equipped icing wind tunnels. The aim is to document the results as accurately as possible by individual 3D scans of the final ice structure. For this purpose, the optical properties of the ice surface have to be changed by applying powders or varnishes. As a consequence, the icing process has to be stopped for the documentation of the ice geometry, which is also only available after the end of every icing test. However, temporal quantitative information about the ice growth would be very relevant from a scientific and industrial point of view.

For these reasons, the objective of this thesis is the development or investigation of an innovative optical measurement system for the time-resolved, three-dimensional documentation of ice growth and deicing processes. The scanning method should allow a three-dimensional measurement of the ice surfaces and their morphological changes during an ongoing experiment in an icing wind tunnel. Since the measurement takes place during the ongoing icing process, the optical properties of the ice can only be influenced to a limited extent or not at all.

Paul Schaffer

With lower and lower emission standards for combustion powered vehicles put into place the need for emission measurements to ensure compliance with those standards is growing. Especially the field of on-road emission measurements has seen substantial interest, as remote emission sensing (RES) technologies pave the way to non-intrusive measurements on a very large scale. Vehicle emissions measured by on-road measurement stations are compared to the legislative emission limits and high emitting vehicles are identified.

In this thesis a spectroscopic measurement approach to quantify on-road vehicle emissions is developed. This measurement approach will allow for a contactless measurement of tailpipe emissions in real time. Using this approach, a measurement device is developed, built and tested under real word conditions on a test track.

By quantitatively measuring vehicle exhaust emissions like CO₂, CO, NO_x, NH₃ and SO₂ as well as O₂ and H₂O,  instead of fraction-based emission factors (CO/CO₂ fraction for example) a more precise classification of vehicle emissions is possible. This leads to an improved detection of high emitting vehicles and helps reducing the environmental impact of internal combustion engines, especially in urban environments.

Christoph Schmidt

Improvements in sensors and functionalities depend on our ability to discover and produce the next generation of sensor materials. Such advanced sensing systems are increasingly based on specialized functions evident in certain materials and not others. However, these sensor materials with such specific functions are often unknown: Often the functions needed are known, but the materials that provide this function are not. In fact, many effects of interest are manifested only in certain materials and not in others. The concept of Inverse Design assumes that the structure controls the material property and that many structures can be realized in the laboratory. Formulating the required functionality/property first and then looking for the material is an inversion of the traditional approach of starting with a given structure and then calculating or measuring the properties.

The thesis concentrates on exploring efficient algorithms to inversely design sensing structures, which will later be applied for finding clever metamaterial and structured matter in the millimeter- and nanometer-wave regime. In inverse design, optimization and search methods (e.g., deep neural networks, genetic algorithms) are applied to directly follow the surface of the functionality and identify structures and configurations whose functionality is close to the desired goal for a given application.

Starting with periodic μm structures and mm waves, the findings will help generate new structures for a variety of sensing functions and ultimately offer new perspectives on the understanding of near field phenomena both in the mm and nm waves regime. Along a similar line, the thesis will exploit inverse design concepts for the creation of mm-Wave devices and on-chip couplers, polarization splitters, and other integrated photonic components.

Michael Töfferl

Millimetre wave technology has a vast variety of use cases, mentioning automotive radar sensors and wireless data transmission. The field of applications is growing over the last years and to exploit the ideas of mm-waves and its wave properties even more, metamaterials come into play. By engineering subwavelength structures one can take advantage of additional physical properties which leads to sensor systems for board spectrum of physical quantities. Within the Christian Doppler Laboratory “Structured matter based sensing” the goal is to find new fundamental concepts of sensing with metamaterials in the GHz regime and to further built ideas for industrial applications with our partners University of Graz, Infineon Technologies and AMS Osram. Together with the research of structured light in the optical regime and in the GHz regime concepts and theoretical models may be interchangeable which leads to new areas of research.

The goal of this thesis is to investigate in clever designs of metamaterials in the GHz regime and find concepts for sensor applications which work fully telemetric. The key is the understanding of the interaction with the metamaterial since different structures can be proposed for different sensor types. A challenging aspect is to find manufacturing processes in the order of microns suitable to create conductive and non-conductive resonator elements. Based on previous work the development of a torque sensor with resonant metamaterial is continued and expanded to enable torque measurement in rotation with additional rotor position detection.