Stefan Cesnik

The LEAD project „Porous Materials@Work” aims on generating a deep understanding of fabrication and simulation of porous materials as well as their application in different field of areas, such as sensing or biotechnology. Our research interests include the study of nanostructured polymer thin films in terms of modeling, fabrication and application. Such thin films have the ability of reacting extremely fast to changes in ambient conditions (as temperature, humidity or pH-value), which makes them a promising material for functional layers in sensors. The deposition of thin films is done with the well-known iCVD (initiated chemical vapor deposition) technique. iCVD offers the advantage to grow those thin films on different types or shapes of substrates. Additionally, it comprises a wide variety of material compositions. For the sensor effect, the goal is to use an optical based detection method and combine it with the physical properties of the nanostructured thin film. Finally, the material we use shows a faster response time than state of the art sensors.

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.

Monika Grafl

The icing of aircraft components is a core problem in ensuring safety in aviation and therefore a major topic in aircraft certification.
For certification of ice protection and detection systems the conditions to which an aircraft is exposed in real flight must be known and replicated on the ground as accurately as possible in icing wind tunnels. For the representative experimental simulation of clouds, the accurate determination of liquid water content (LWC) and ice water content (IWC) of large droplets is still a challenge. With recent regulatory changes, the demand for separately measuring the phases of water in icing conditions has increased.

The aim of this thesis is to develop a spectroscopic measuring device for LWC/IWC discrimination capable of measuring in harsh environments like icing wind tunnel conditions.

The first step of the work involves the design of a measurement system and experimental validation of the technology for reliable measurement of phase fractions in icing environments. Afterwards a fundamental prototype based on the developed concept will be manufactured and the measurement capacities will be evaluated in the Icing Wind Tunnel.

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.

Samuel Hörmann

Biomedical analysis is shifting from lab-based analysis towards point-of-care solutions which enable a cheap, fast and, thus, more extensive monitoring of biomarkers that are critically connected to the overall health of the patient. To this end, integrated photonic sensors are unlocking the interaction of light with organic molecules and tissue for labs-on-a-chip and the internet of things. Consumer applications in particular are showing a soaring, yet unsatisfied, demand of biomarker sensor solutions. Furthermore, silicon photonics is a flourishing field with promising applications in high-speed communication, computing, sensing and scientific research. It provides highly scalable and integrated devices by wielding the same mature fabrication processes perfected by the electronics industry in the past decades.

The emphasis of this thesis lies on the system aspect of developing an integrated label-free biophotonic sensor. The goal is to engineer a versatile silicon nitride platform that can sustain cutting-edge refractometric approaches and to build a prototype device with bio-functionalized waveguides. The existing sensing architectures are to be evaluated and the current process of ams OSRAM is to be adapted for a highly sensitive design that is robust within the manufacturing and noise limitations.

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.

Markus Knoll

Black carbon (BC) is well known for having an impact on health and our environment, whereby combustion-based vehicles are one of the main contributors. Currently, the emissions of combustion based vehicles are mainly determined during type approval or whilst periodical technical inspections (PTI) in controlled driving conditions. However, real world driving emissions can deviate substantially. Remote emission sensing (RES) is a promising approach for the non-intrusive measurement of real world emissions. With RES individual high emitters or even specific vehicle fleets can be traced. At present, a few commercialized RES systems exist which deliver accurate emission factors for gases but lack accuracy in the detection of particulate matter (PM). Concepts exist to quantify PM with non-intrusive approaches such as plume chasing or point sampling, but these methods have not been fully evaluated yet. Potential instruments must be able to capture the transient events of passing vehicles and must bring along a high sensitivity to resolve small concentrations due to exhaust dilution in air.

In this thesis, different methodologies in regard of RES are evaluated in particular concerning PM. In the course of the thesis an instrument is developed which can be employed for real time measurement of PM in RES.

Markus Koller

Current Battery Management Systems (BMS) in larger Lithium-Ion secondary battery (LIB) packs determine the State of X, meaning, among others, the State-of-Charge (SoC) and the State-of-Health (SoH) via a single parameter or via a combination of multiple parameters derived from the electrical two pole behavior, or the history of the battery. These parameters are typically the cells’ voltage, current, impedance, and capacity, and the number of charge and discharge cycles. Structural defects like swollen or deformed batteries are difficult to recognize with current BMS. Such unnoticed mechanical damage can result in serious fires and injuries. However, with the usual parameters it is difficult to draw conclusions about the mechanical state of the battery.

This work aims to improve the estimation of the State-of-Safety (SoS) as well as the State-of-Function (SoF) by determining the mechanical properties of LIB batteries. For this, additional mechanical sensing is implemented, using small- sized and low-cost piezoelectric ultrasound transducers as emitters and sensors mounted on the surface of pouch cells. During cycling, the transmitted ultrasound signal changes its properties such as amplitude and Time of Flight (ToF), which correlate with the changing mechanical properties as well as the SOC.

Helmut Krasa

The legislature on particle number emissions in combustion engine vehicles is becoming increasingly stringent. Future European emission legislation for vehicle homologation will reduce the particle size limit from 23 down to 10 nm in a first step for light-duty vehicles and subsequently for heavy-duty vehicle types. Furthermore, on-board vehicle testing is being increasingly introduced in legislations, causing new challenges for the conditioning and subsequent measurement of particle number concentration.

The aim of this thesis is to further investigate a sensor principle based on electrical diffusion charging and develop a device capable of measuring real driving emissions in motorcycle vehicles, which requires a lightweight, mobile and robust design.

In a first step, a novel piezoelectric plasma generator by TDK, called CeraPlas®, will be evaluated for its use as charging device of the aerosol particles. If the piezoelectric unit is driven in resonance mode, it provides a high output voltage, ionizing the surrounding gas and can therefore be used as an ion source for aerosol charging. A successful implementation would subsequently allow for a reduction in power consumption, cost and size of a diffusion charge based particle counter.

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.

Ulrich Radeschnig

The photothermal spectroscopy (PTS) is a sensorial method for sensitive and selective detection of gases and/or aerosols. With this approach, this PhD thesis focuses on the development of a fast, miniaturized and robust sensor method for monitoring specific gases such as H2O or black carbon. PTS uses the effect of temperature change of air surrounding molecules/particles irradiated by light. By periodically irradiating a target with a modulated, high-intensity laser, we can detect this as a signal using via the use of an interferometer. The signal depends on the concentration of the specific target, which allows determination of the targets mass concentration. Using proper configurations, an accurate and robust measurement of the targets mass concentration therefore is achievable. As a result, this opens up possibilities for measuring a specific target of interest with the distinct advantages of low response times and small sensor size while providing a signal that shows minimal dependence upon harsh environmental influences (e.g. mechanical vibrations or environmental noise).“

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.

Alexander Schossmann

Torque sensors have a vast variety of applications within the scope of the increasing automation in everyday technologies. As fundamentally important part in every servo-assisted steering system they are indispensable for the automotive sector. Moreover, precise torque data of drivetrain components allows for an elaborate analysis of engine performance, automatic transmissions or torque converters. Concerning the road towards autonomous driving, torque sensors are essential for drive control as well as in the improvement of safety systems such as traction control systems or electronic stability controls. In the emerging field of collaborative robotics, it is obligatory to have highly integrated force sensors that enable rapid reactions in the interaction with humans. Thus, it is evident that torque sensors are subject of current research with the aim of providing elaborate solutions for the increasingly complex demands in the aforementioned fields of application.

The objective of this dissertation is to develop a completely new concept of torque sensor based on tunable metamaterials. Therewith, it is expected to provide a sensor design that has a unique selling point compared to currently available products.

The first part of the work consists of an elaborate literature research in order to identify the state of the art and to determine a first target application. Thereupon, an analytical approach for the description of metamaterial structures is worked out. This serves as a basis for subsequent numerical simulations, which are an important part of the design process. Further, the experimental analysis of the measuring principle is a central topic of the work. In the final process of developing a practical torque sensor system, the challenging demands in the context of automotive industry as well as collaborative robotics have to be considered. The realization of the new torque sensor is carried out in collaboration with Infineon Technologies AG.

Manuel Tanzer

The increasing awareness to the impact of aerosols and trace gases such as black carbon, CO2 and CO on health and environment increases the demand for reliable, miniaturized and cheap sensor solutions. Fast growing markets for mobile applications as well as the automotive and biomedical sector, just to name a few, require high performance sensor systems while being small in size and suitable for high volume production.

In recent years photothermal spectroscopy (PTS) received a lot of scientific attention due to unprecedented sensitivities and selectivity as well as the potential for building rugged and compact sensor systems, with minute susceptibility to mechanical vibrations.

To close the gap between laboratory setups and commercially available products and to meet the aforementioned demands on gas and aerosol sensor solutions, two distinct approaches, based on PTS, are being investigated within the scope of this thesis.

On the one hand, an all-photonic aerosol sensor based on optical fiber technology will be developed in cooperation with the University of Maribor.

On the other hand, a miniaturized, large-scale producible on-chip CO2/CO sensor will be realized together with ams AG and the TU Vienna.

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.

Johanna Unterkofler

Lithium-ion batteries are widely used as power sources in portable devices as well as in hybrid electric vehicles and electric vehicles and the demand will increase further. To ensure a proper and safe operation of the cells in a vehicle a battery management system (BMS) is used. These systems monitor the voltage, the current and other parameters of the cell to estimate the state of charge (SOC). With these measurements, the physical state of the cell cannot be fully represented. Additional concepts are needed to get more insight in the mechanical behavior of the cell to detect failures such as thermal runaways in an early state and enhance the safety of the cell. Optical fibers are promising candidates for such sensors as they are immune to electromagnetic interference and show good performance in harsh environments.

In this thesis the mechanical properties of lithium ion cells will be observed by using optical fibers with inscribed fiber Bragg gratings (FBGs). Several FBGs can be inscribed in one fiber, so the attached and also inserted fibers can measure temperature and strain evolution spatially resolved. With these sensors deeper understanding of the chemical reactions and mechanical changes during cycling of a lithium-ion cell should be gained.

Tanja Wallner

To guarantee compliance with the latest emission standards advanced and easy to use technologies for particle measurement, especially for small particles and very low concentrations, have to be designed. Electrostatic particle measurement offers great potential for the detection of charged particles in harsh environments. An aerosol is conveyed into a high voltage region between two electrodes and the resulting sensor signal is proportional to the aerosol particle concentration. Despite the simple sensor principle, the underlying effect up to now remains poorly understood.

In this dissertation a novel electrostatic particle sensor is developed incorporating an optically accessible measurement region to assess the existing ambiguity in the literature about the underlying physical effects that cause the measurement signal. Furthermore, a comprehensive characterization of the designed sensor and a commercially available sensor, including the effects of different particle species, particle sizes and charge distributions as well as different ratios of organic to elemental carbon will be conducted. The results from the characterization will be compared with an analytical model to address the question if an electrostatic sensor is suitable to be used in a mini-PEMS setup.