Currently running research projects
DFG project "Measurement of neuronal activity with combined multifunctional micro NMR probes and micro electrodes"
Joint project with K. Scheffler, MPI Tübingen and Bruker BioSpin
PhD student: Jonas Handwerker, MSc
Conventional fMRI experiments are based on the BOLD effect, a local neuronal activity induced change in blood oxygenation, which allows for the detection of neuronal stimulation through the corresponding local susceptibility changes. This change in local susceptibility is usually measured with T2* sensitive EPI sequences with a temporal resolution in the range of seconds and spatial resolutions of several microliters. This research projects aims at overcoming these limitations in spatial and temporal resolution with the goal of assessing finer details of the basic neurovascular coupling cascade. Here, the main goal of this project is the detection of neuronal activity-related changes of proton magnetization at a significantly improved temporal resolution and sensitivity within small volumes of a few nanoliters accompanied by simultaneous recording of electrical activity. To achieve these goals, a microsystem consisting of a miniaturized MR coil and a custom designed ASIC mounted on a common needle-shaped substrate is developed.
PhD student: Anh Chu
Methods based on the electron spin resonance (ESR) effect are amongst the most powerful analytical techniques in medicine as well as in the natural and material sciences. They enable to study the structure, dynamics and spatial distribution of paramagnetic species.
Despite the possibility of detecting the ESR phenomenon with many different physical principles, some of them displaying significantly better spin sensitivities, inductive detection, due to its non-invasive nature and its full compatibility with all biological samples, is by far the most versatile ESR detection method.
Building upon this fact, the goal of the proposed research project is to further develop and improve a novel frequency-sensitive approach for inductive ESR detection, which uses an LC tank oscillator as both B1-field source and ESR detector.
Project within SPP1601: New frontiers in sensitivity for EPR spectroscopy: from biological cells to nano materials
PhD student: B. Schlecker
The main goal of the proposed project is to improve and/or to enhance the functionality of existing electron spin resonance (ESR)-instruments for two specific applications from the fields of life science and material science by efficiently using the capabilities of modern integrated circuit (IC) technologies for the manufacturing of miniaturized, highly sensitive detectors for inductive and electrical measurements of the ESR effect.
DFG project "A dynamic domain decomposition method for solving coupled multiphysics problems based on a distributed software agent environment"
Joint work with M. Weyrich, IAS, University of Stuttgart
Ph.D. student: Sebastian Grabmaier
The optimization of the efficient and flexible calculation process of complex three-dimensional coupled field problems, calculated by software agents, during run time is the goal of this project. Previous work shows, that the use of multiple software agents within a multi agent system using specialized algorithms of numerical field calculation such as the finite element method or boundary element method provide the efficient and flexible calculation. Therefore, the simulation is statically split on classes of problems like the included physics, its domains or available resources. The order of the separation is based on the strength of the expected coupling between the partial problems. This represents the usual approach to computations on distributed resources. The calculation of the partial problems as well as considering related couplings are done decentralized within the software agent system considering available computing resources, the capabilities of the calculation agent and their workload. A validation of the splitting - and thus also the coupling hierarchy is possible during runtime based on information, such as the convergence behaviour or the current state of partial calculations. Due to non-linear coupling between the partial problems, and due to the nondeterministic behaviour of every distributed cluster, a dynamic coupling hierarchy is numerically beneficial for the convergence of an iterative distributed calculation approach. Based on the existing agent system a dynamic consideration of the coupling is possible by an active coordination based on intelligent and learned decisions. Accordingly, the implementation of a learning system using a knowledge base for storable parameters of a coupled systems. This also includes the distributed, decentralized architecture where knowledge is not generated centrally, but on different units available only temporarily. Taken recommendations from the knowledge base into account is done within the numerical iterative solution procedure by adapting the calculation process. The final evaluation of the achieved results completes this project. It is done with special attention to the achieved optimization of coupled systems calculation calculated with decentralized and autonomously acting agents. An additional point is the comparability and gain achieved by the learning system.
Joint project with P. Fries, Ernst Strüngmann Institute (ESI) Frankfurt and M. Pannetier-Lecoeur, CEA France
Ph.D. student: Ayman Mohamed
Low-frequency magnetic fields pass through biological tissues without significant distortion, thus enabling efficient, remote interaction with devices inside a biological system. Previously, we have realized the first experimental proof of concept of locally recording the activity of neuronal networks in vivo with a new type of tool based on spin electronics. To realize single-event recordings at neuron scale, we need to improve the sensor sensitivity and to co-integrate the electronics with the sensor for an improved form factor and signal integrity. To achieve this, in the proposed project NeuroTMR, we will use our low-noise Tunnel Magneto Resistance sensors and incorporate all relevant electronics directly onto the probe. The resulting new tool will open the field of magnetophysiology to understand the mechanisms of neuronal information transmission by realizing a mapping of the ionic flows in the neuropil, including vectorial information and multi-neurons simultaneous recordings, paving the way for durable implants, possibly for brain-machine interface.
PhD student: Matthias Häberle, MSc
The proposed research training group PULMOSENS is focused on innovating sensory methods and its application to the functional examination of the lung epithelium under physiological and pathophysiological conditions. For this purpose novel measurement systems will be developed for single cells, differentiated epithelia, epi-endothelial co-cultures as well as the whole organ. In the medical field, scientific goals are to gain elementary knowledge for pulmonary function under physiological and pathophysiological conditions, while the development of innovative methods for integrated sensory and analytical systems are intended on the engineering and natural sciences side. These systems will enhance the detection sensitivity and spatial resolution as well as enable multimodal measurements, or such systems are developed which are specialized in the lung epithelium, and which allow new approaches to elucidate mechanisms at the molecular, cellular level and on organ level. Using extensive collaboration of engineers, natural scientists and medical researchers, as well as by the cooperative integration of external users it will be assured that the new concepts are continuously checked for their practical relevance. On long term, the methodological/technological advancements shall be utilized in diagnostics and therapy. A further fundamental objective of PULMOSENS is the joint training of young scientists in a very interdisciplinary context between the life sciences, natural sciences and engineering sciences to break down the language barriers at an early stage of their scientific career, and to further strengthen the interdisciplinary research profile of Ulm University. In addition to the already established junior-professorship for Integrated Biomedical Sensors another junior-professor and a habilitand are centrally involved as applicants for the promotion of young scientists; another postdoc position is planned in PULMOSENS. In engineering and the natural sciences, the research subject of PULMOSENS is also considered as a measure to enhance the attractiveness to female young researchers. Through cooperation with the study programs Biophysics, Advanced Materials and Sensor Systems Technology the visibility of PULMOSENS to students is increased. Cooperation with UULM PROMint&MED will improve the research starting phase and PhD process.
Joint project with F. Jelezko, University of Ulm, Institute of Quantum Optics
PhD student: D. Djekic
Since its inception in the late 1970’s, magnetic resonance imaging (MRI) has made an enormous impact on human health. Yet for all its diagnostic power, conventional MRI technologies are limited to resolutions greater than micrometers and samples consisting of roughly one trillion atoms. The development of single‐spin sensitive MRI techniques is expected to revolutionize the MRI field by allowing for non‐invasive chemical analysis at the nanoscale. In contrast to electron and scanning force microscopy, the technique is performed under ambient conditions, where molecular dynamics may also be investigated. For example, single spin MRI would enable the direct imaging and structural determination of individual molecules such as membrane proteins, which are notoriously difficult to crystallize for X‐ray crystallography. Additional applications include rapid sequencing of individual DNA strands without amplification, and development of a critical tool for rational drug design. The experimental framework is based on controllable magnetic dipole interaction between shallow NV centers and nuclear spins near the diamond surface.
In this project, we are researching PLL-stabilized, VCO-based B1-field sources between 9 and 84 GHz, which ae specifically adapted for NV sensing applications.
IQST project "Light‐matter interaction through the Josephson‐Effect: The Josephson Junction as a Light Source"
Joint project with C. Ast, MPI Stuttgart, K. Kern, MPI Stuttgart and J. Ankerhold, University of Ulm
The Josephson effect is among the most versatile phenomena in solid state physics, because of its extreme sensitivity to the environmental conditions. Its most notable application is in the definition of the voltage standard allowing the volt to be measured to much higher precision than was previously possible. Even more than fifty years after its discovery, there are regimes of the Josephson effect that remain to be explored and better understood. In general terms, this concerns the interaction of light and matter by means of the Josephson effect. More specifically, we are interested in how the Josephson effect can be exploited as a microwave light source and how the generated light interacts with the tunneling Cooper pairs in the Josephson junction.
In this project, we are developing specifically adapted, high B1-field microwave sources.
IQST project "Pseudoresistor‐based transimpedance amplifiers for high‐speed, highresolution sensing of Rydberg excited gases"
Joint project with P. Schalberger, IGM, University of Stuttgart and T. Pfau, PI5, University of Stuttgart
The use of hot Rydberg excited gases flowing through electrically contacted glass cells offers the possibility of assembling gas sensors which are sensitive in the ppb regime. Currently, a first demonstrator for the detection of smallest amounts of Rb in an N2 gas flow is being built in a cooperation between the 5th Institute of Physics (5th PI) and the Institute of Large Area Microelectronics (IGM) at USTUTT. Preliminary results indicate that the achievable resolution and operation speed of the sensor is limited by the quality of the necessary transimpedance amplifier (TIA) in the readout circuit. This amplifier needs to have a high gain and a low offset and also needs to provide a low input referred noise and a very low input capacitance to maximize the achievable bandwidth.
In this project we are researching and developing new TIA concepts for high-speed low-noise current sensing, which are compatible with the harsh environment provided by the Rydberg gas cells.
IQST project "Miniaturized single-chip wide-range magnetometers as a tool to enhance magnetic field stability and homogeneity in performance critical setups (MiniMag)"
Joint: project with F. Jelezko, University of Ulm, Institute of Quantum Optics and Bruker BioSpin
Ph.D. student: Jianyu Zhao, MSc
A large number of classical magnetic resonance as well as quantum sensing systems, including many setups utilized by partners of the IQST alliance, critically depend on the quality of the utilized external magnetic field. Therefore, these systems typically employ at least one closed loop feedback loop to stabilize this external magnetic field to the desired precision. Amongst the different options to realize the magnetic field sensor for the closed loop system, NMR magnetometers stand out thanks to their unsurpassed precision at higher field strengths (approximately >0.1 T) under ambient conditions . However, a wide usage of NMR magnetometers is today still prevented by the large size and high instrument cost of commercially available instruments. Here, the bulky instrument size frequently also prevents an in-situ placement of the magnetic field sensor right at the relevant location(s). Moreover, the large size, high system complexity (one shoebox- or even rack-size instrument in addition to the NMR probehead) and high instrument cost prevent a placement of a multitude of sensors to obtain spatial maps of the magnetic field under investigation.
In this project, we are aiming at developing monolithic widerange NMR magnetometers whose sensitivity and miniaturized form factor will allow for the detection of magnetic fields with high excellent magnetic field and spatial resolution.
MWK Baden Württemberg "Integrated readout electronics for combined high-speed scanning ion conductance microscopy and high-resolution patch-clamp experiments"
The ability to image in non-contact mode with subcellular resolutions makes scanning ion coductance microscopy (SICM) a promising method for molecular biology studies. Recent innovations in the field of probe heads in combination with new imaging modes have improved the resolution, stability, and imaging time in SICM experiments, making SICM an interesting exploration method for a wider range of applications.
Our goal in this project is to research and develop prototypes of integrated transimpedance amplifiers (TIAS), which can help to overcome the existing speed limitations of current SICM setups.