Our Projects

In this DFG funded project we study a new class of biodegradable electrets and ferroelectrets based on Polylactide Acid (PLA) and its derivatives. These have the potential of an adjustable biodegradability and suited electrical performance, i.e., sufficient charge storage and thermal charge stability. Based on our previous research, also funded by DFG (KU 3498/1-1, SE 941/21-1) and in order to obtain the energy efficient electromechanical conversion for these mechanical-based sensors, we propose using a polymer-air composite (hybrid) structure with geometrically defined air-filled and electrically charged voids. These mechanically soft hybrid systems allow achieving high piezoelectric coefficients even for very weak polar polymers such as PLA. Therefore, investigating and improving charge storage and its thermal stability is essential, since these are the most important properties to obtain high and persistent piezoelectric coefficients in biodegradable electret and ferroelectret hybrids to be used in mechanical-based sensors for quantities such as force, pressure, torque and acceleration.

Original Publication: S. Zhukov, X. Ma, H. von Seggern, G. M. Sessler, O. Ben Dali, M. Kupnik, and X. Zhang, “Biodegradable cellular polylactic acid ferroelectrets with strong longitudinal and transverse piezoelectricity”, Applied Physics Letters, vol. 117, no. 11, p. 112 901, 2020. DOI: 10.1063/5.0023153.

Listen2Future aims to promote the potential of piezoelectric acoustic transducers for new solutions in the fields of health, digital industry and energy. Acoustic transducer solutions and the underlying key technologies can be the answer to many of the challenges arising from new fields of application for an increasingly digitalized society. In medical and industrial products, the need for “Micro-Electro-Mechanical-Systems” (MEMS) is increasing. Such minaturized electromechanical transducers with low power consumption in the form of microphones and ultrasonic transducers are being further developed and researched in this project. The goal is to improve acoustic sensors with new piezoelectric materials and technologies to outperform existing sensors based on capacitive MEMS technologies and to open up new application areas.

The project involves 27 partners from academia and industry from seven nations in the European Union.

Check out the Listen2Future website

Conventional fiber optics have three central challenges that need to be addressed with regard to various research and application areas:

• The damage threshold of solid-state optical fibers limits the further development of technologies (such as inertial confinement fusion) that require high laser powers.
• In addition, the transmittable signal bandwidths are limited.
• Dynamic adaptability of optical transmission properties is only possible to a limited extent.

In the interdisciplinary joint project SPOTLITE, these challenges are being addressed together with the Deutsches Elektronen-Synchrotron (DESY). Building on the already successful demonstration of the method for controlling light using intensive ultrasound fields ( Lasers deflected using ultrasound), the aim of this project is to demonstrate low-loss light waveguiding through an acoustically modulated gas phase in a cylindrical resonator.

In this context, the Department of Measurement and Sensor Technology is dedicated to the investigation and realization of sono-photonic waveguides through the analysis of ultrasonic parameters and geometry optimization of such resonators. The aim is to generate stable, cylindrical ultrasonic fields that are also dynamically adaptable. This enables the implementation of customized refractive index fields for a wide range of optical applications.

The research project is funded by the Federal Ministry of Education and Research as part of the Research Program Quantum Systems under the contract number 13N17124.

Leg prostheses, orthoses and exoskeletons become active movement assistance systems by individually and situation-specifically detecting their users' movements and providing them with appropriate force and torque support. Such an assistive device can be seamlessly integrated into the human body schema if it is able to automatically recognize different movement intentions and consequently generates an intuitive and predictable motor behavior. In this way, it integrates seamlessly into the daily experiences of movement.

The research training group LokoAssist (RTG 2761 Project number 450821862) brings together researchers from different disciplines, such as human sciences, computer science, engineering, and medicine, in order to tackle the diverse and interdisciplinary challenges in the development of such assistance systems. In particular, the project area A3 investigates integrated sensors and sensor fusion in order to measure and analyze the state variables of the user as well as the assistance system, which is crucial for suitable assistance.

LokoAssist website

In Industry 4.0, the quality of process data is of crucial importance for all subsequent processes. Connecting elements are particularly suitable for this as they are in the force flow and can be replaced without constructive changes.

As part of the DFG project SiSmaK (priority program 2305: Sensor-integrated machine element),

the FG Measurement and Sensor Technology is working on the multi-axis measurement of mechanical loads in screws. This allows bending moments to be recorded in addition to the axial forces used for the configuration. Despite all adaptations to the machine element, the load-bearing capacity is to be maintained and universal applicability is to be ensured by full electronics integration and energy approach.

In addition, the design methodology for mechatronic systems is being extended to sensor-integrated machine elements as part of this project.(DFG project no. 466650813)

Structural integrated force and torque sensors are increasingly required in fields such as monitoring in plant construction, medical engineering and light weight construction. All these fields share the requirement of complex structures. Thus, an integration of commercial general-purpose sensors, which are conventionally manufactured, is not possible or only with considerable effort. Conventional manufacturing methods based on machining the deformation body and subsequent application of strain sensing elements limit the design geometry and size of a deformation element. Additively manufactured force and torque sensors create added value as they allow a high degree of individualization and adaptation to application-specific needs.

In this project (DFG project no. 418628981), the fundamental aptitude of additive manufactured deformation elements with laser-based powder-bed-fusion for force sensors is investigated. The objective of this project is to develop reproducible methods for the structural integration of strain sensing elements in additively manufactured components with force sensing function.

For many applications, such as structural health monitoring, medical applications, autonomous vehicles and environmental monitoring systems, the need for sensor networks steadily increases. Often, the sensors are positioned at remote places where the availability of electrical power or possibilities such as replacing or recharging batteries are challenging tasks. Therefore, other methods for powering electronic circuitry, such as energy harvesting, have been a growing field of study for the last 20 years.

The objectives (DFG Project number 392020380) of this project are the design of new ferroelectret materials and their use in energy harvesters based on the transverse piezoelectric effect in these materials.

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Conventional methods for directional control of light, such as the use of mirrors, have significant limitations as they can cause wavelength-dependent losses or even complete absorption of light. In particular, at high levels of light power, the optical properties of solid-state materials are often limited. Instead, SOPHIMA employs non-contact methods for manipulating light by utilizing ultrasonic waves (Sono) to control light in gases. The project involves extensive fundamental research for developing novel methods, such as Sono-Photonic Light Waveguides, Phase Modulators, non-linear and active optical elements, as well as back-action-free optical methods for measuring acoustic phenomena and sensors in gases.

By integrating non-linear optics, laser physics, and electrical/ultrasound technology, SOPHIMA opens up a new field of research with great potential for scientific and industrial applications. The project aims to enable fundamental control and guidance of light in a novel and innovative way, thereby revolutionizing a multitude of applications in various fields.

Original Publication:

Acousto-optic modulation of gigawatt-scale laser pulses in ambient air; Yannick Schrödel, Claas Hartmann, Tino Lang, Jiaan Zheng, Max Steudel, Matthias Rutsch, Sarper H. Salman, Martin Kellert, Mikhail Pergament, Thomas Hahn-Jose, Sven Suppelt, Jan Helge Dörsam, Anne Harth, Wim P. Leemans, Franz X. Kärtner, Ingmar Hartl, Mario Kupnik, Christoph M. Heyl; „Nature Photonics“, 2023; DOI: 10.1038/s41566-023-01304-y

SOPHIMA website of the Carl Zeiss Foundation

Every year, more than 20 million square meters of sandwich elements are produced for the construction sector in Germany, and as many as 200 million in total in the European Union. There is potential for savings in materials and energy by optimizing production processes. To promote resource-efficient production of sandwich elements, the German Federal Ministry for Economic Affairs and Energy has launched a new research project called “Resource-efficient sandwich elements through non-destructive monitoring for lightweight construction ReSaMon.”

Sandwich elements consist of two thin metallic face sheets and a core of rigid polyurethane foam and are important building products. However, potential weak points such as damage due to heat-induced stresses are not always detectable in the manufacturing process and only appear during processing on the building site. This leads to complaints, longer construction times and other problems.

The “ReSaMon” project team will develop a new non-destructive ultrasonic measurement technique that can immediately detect flaws and inaccuracies to identify potential weak points and changes in material properties during the production process. The measurement technology works without contact and therefore does not interfere with the production process. The construction industry and end users will benefit from this technology.

The project consortium consists of industry partners, sandwich panel experts, metrology specialists and simulation experts who are bringing their expertise together to achieve a better understanding of the influences of production on product properties. The project partners include the Fraunhofer Institute for Structural Durability and System Reliability LBF, the Institute for Steelwork Technology IFSW, the company Inoson, manufacturers such as ArcelorMittal and Covestro Deutschland, and us, the Measurement and Sensor Technology (MuST) department at TU Darmstadt as a research partner focusing on ultrasonic measurement technology.

Autoclaves, self-sealing devices, are widely used in industries such as medicine, chemistry, and construction. In a specific project for the production of calcium silicate and aerated concrete, the challenge is addressed to precisely determine the optimal time to safely open the autoclave, aiming to optimize efficiency and safety. However, conventional pressure sensors in autoclaves exhibit inaccuracies due to calibration issues and deposits in the steam flow.

The project aims to develop an innovative turbine wheel sensor for autoclaves. The sensor utilizes powered coils to measure the rotational speed of the turbine wheel, which is driven by steam. By integrating actuator functions, the sensor can be self-monitoring, perform self-tests, and calibrate independently. The development includes the design of the turbine wheel, electrical connection, electronic evaluation, and method development, tested in various phases starting with a demonstration and laboratory model. The electronics are connected via shielded cables with indicator lights and a control element, requiring special protection against electromagnetic interference from three-phase and asynchronous machines. The development goes through three phases: fundamental development and design, verification of variations and optimization, and the realization of the final prototype.

The R&D project, under the ZIM funding framework, collaborates with partners MUST from TU Darmstadt and Eitner GmbH, a medium-sized company, focusing on developing new concepts specifically for small and medium-sized enterprises (SMEs). ZIM funding aims to support innovation projects for SMEs, provided by the AiF within its Research and Transfer Alliances, targeting the development of future technologies and industrial transformation with a focus on climate neutrality and sustainability.

In this project (DFG project no. 172196622), a teleoperation system with a parallel kinematic structure was developed with interchangeable surgical instruments (e.g. grippers) as end effectors and five degrees of freedom.

The main application of cardiac catheterization is the in-depth diagnosis and treatment of arteriosclerosis. Various types of deposits (plaque) in the coronary arteries can lead to a reduction of the internal cross-sectional area, thus to reduced blood flow and consequently to heart attacks. For minimally invasive diagnosis and treatment of arteriosclerosis, a thin guide wire with a diameter of 360 μm is used. This guide wire is inserted usually through the femoral artery at the groin or the radial artery at the wrist into the patient's vascular system and pushed into the coronary vessels to the area to be treated. For this purpose, the physician has to navigate the wire tip, which is located in the vessel, through twisting and pushing the distal end. Difficulties arise due to a lack of haptic feedback, which complicate navigating through the coronary vessels.

The objective of this project (DFG project no. 5429061 and 212414892) were the design and implementation of a haptic assistance system for catheterizations in medical diagnostics and therapy. The approach is based on a force measurement at the guide wire tip and an integration of a haptic control unit in the treatment process. This control unit generates haptic feedback for the physician based on the scaled force signals.