Search results for: Peter Woias

Items from 1 to 20 out of 51 results

article

Heat Transfer Modeling of Confined Bubble Evaporation in a Microchannel

Sahba Sadir, Mohammadmahdi Talebi, Peter Woias, Roland Dittmeyer, more

PAMM > 19 > 1 > n/a - n/a

In this study, we model the heat transfer mechanism for a single nucleate vapor bubble which then expands to an elongated bubble during evaporation in a microchannel. The model is a logical mix of empirical correlations and analytical models and is defined for the two steps of bubble growth including: (a) partially confined growth, in which the bubble expands from nucleation site until it fills the...

article

Analysis of impedance data from bubble flow in a glass/SU8 microfluidic device with on-channel sensors

Mohammadmahdi Talebi, Peter Woias, Keith Cobry

Sensors and Actuators A: Physical > 2018 > 279 > C > 543-552

This paper presents the design and original fabrication of a fully transparent microfluidic reactor with integrated electrical sensors over the microchannel. The transparent chip design allows for microscale photochemistry, and permits direct, real-time visual and electrical observation. The microchip uses optically transparent indium tin oxide (ITO) electrodes as sensing elements for in-channel phase...

article

Complete Thermoelectric Characterization of PEDOT:PSS Thin Films with a Novel ZT Test Chip Platform

Vincent Linseis, Zeinab Mohamed Hassan, Heiko Reith, Javier Garcia, more

physica status solidi (a) > 215 > 7 > n/a - n/a

For the first time, a complete thermoelectric characterization of PEDOT:PSS thin films is performed with a novel lab‐on‐a‐chip measurement platform, which Is developed for the nearly simultaneous in‐plane ZT characterization. The electrical conductivity, the Seebeck coefficient, the thermal conductivity, and consequently the power factor and ZT values as a function of temperature in a single measurement...

article

Laser rapid-prototyping and modular packaging of chip-based microreactors for direct fluorination reactions

Dawid Cichowski, Pengcheng Zhang, Peter Woias, Ingo Krossing, more

Chemical Engineering Research and Design > 2017 > 128 > C > 318-330

We have developed a laser rapid-prototyping method for the realization of microchannels and nozzles in silicon and nickel chips. A practical application of such microreactors, made by rapid prototyping, is the direct fluorination of organic substrates via microbubbles, a highly exothermic and chemically harsh reaction. By employing optimized laser raster ablation procedures, different channel cross-section...

chapter

Optimized detector for closed-loop devices for neurostimulation

Farrokh Manzouri, Andreas Schulze-Bonhage, Matthias Dumpelmann, Simon Heller, more

2017 IEEE International Conference on Systems, Man, and Cybernetics (SMC) > 2158 - 2163

2017 IEEE International Conference on Systems, Man and Cybernetics (SMC)

Brain machine interfacing (BMI) needs continuous analyses of ongoing brain activity. For a successful interaction, related brain activities and events should be reliably detected; using various approaches including machine learning techniques. To this end, a variety of characteristic signal features as well as different types of classifiers can be used. One possible application of such an interaction...

chapter

The deformable valve pump (DVP)

Ardavan Shabanian, Frank Goldschmidtboeing, Hitesh G. Bettaswamy Gowda, Chiranjeevi C. Dhananjaya, more

2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS) > 1777 - 1780

2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS)

We present a device for fluid handling which utilizes a novel concept for a reciprocating micropump, employing our high stroke buckling piezo-membrane-actuator. Previously we have reported on the valving functionality of the device at 70 kPa of counter pressure. Here, the novel pumping concept of the device is explained. The fabrication methods are described and experimental results are presented...

chapter

Coupled piezoelectric nonlinear transduction array for turbulence manipulation

Muhammad bin Mansoor, Nico Reuther, Soeren Koeble, Tin Wang Wong, more

2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS) > 2039 - 2042

2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS)

This article reports on the experimental design and optimization of a piezoelectric bimorph transducer array used to create large amplitude and high frequency vibrations at an airfoil surface demonstrating an active flow control strategy. Broad-band resonant surface vibrations are created with the help of a metal / ceramic composite actuator design which operates in a nonlinear regime. The array design...

article

Parametric modeling and experimental characterization of a nonlinear resonant piezoelectric actuator designed for turbulence manipulation

Muhammad bin Mansoor, Nico Reuther, Sören Köble, Mélanie Gérard, more

Sensors and Actuators A: Physical > 2017 > 258 > C > 14-21

In this work we fabricate and optimize a resonant piezoelectric actuator designed for the manipulation of turbulent flow at airfoils and propose analytical expressions for its nonlinear vibration characteristics. High frequency large displacement manipulation of the turbulent boundary layer offers a promising route to influence the frictional drag and hence minimize fuel consumption in modern aviation...

article

Cost effective MEMS fabrication of a nanowire characterization platform with solder coated electrodes

S.Hoda Moosavi, Michael Kroener, Peter Woias

Sensors and Actuators A: Physical > 2016 > 246 > C > 140-147

In previous research [1–5] we have successfully performed the design and application of thermoelectric nanowire characterization platforms (TNCPs). These chip-based measurement platforms are used to characterize single nanowires from a structural, electrical and thermoelectric point of view. For this purpose, a TNCP must carry electrical contacts in a tight spacing, exhibit a long and very small gap...

article

Surface effects on thermoelectric properties of metallic and semiconducting nanowires

Danny Kojda, Rüdiger Mitdank, Stefan Weidemann, Anna Mogilatenko, more

physica status solidi (a) > 213 > 3 > 557 - 570

Metallic and semiconducting nanowires (NWs) are of interest in the field of thermoelectrics, because they act as model system to investigate the influence of surfaces on the thermoelectric transport properties. In single crystalline NWs, the grain boundary scattering is negligible and the surface‐to‐volume‐ratio is high. We present state‐of‐the‐art of the combination of the structural, chemical, and...

chapter

Theoretical and Experimental Investigations of Convective Micromixers and Microreactors for Chemical Reactions

Simon Dreher, Michael Engler, Norbert Kockmann, Peter Woias

Heat and Mass Transfer > Micro and Macro Mixing > Part 4: Macro- and Micro-Mixing in Micro Channel Flow > 325-346

Convective micromixers allow fast mixing with characteristic times below 1 ms by creating vortices in bends or junctions of microchannels. Their robustness and comparatively high throughput make them suitable for process intensification purposes. In this contribution, T-shaped micromixers with rectangular cross section and meandering structures as basic elements are numerically investigated for Reynolds...

chapter

Design and optimization of nonlinear oscillators for drag reduction on airfoils

Muhammad bin Mansoor, Soeren Koeble, Peter Woias, Frank Goldschmidthboeing

2016 IEEE 29th International Conference on Micro Electro Mechanical Systems (MEMS) > 1129 - 1132

2016 IEEE 29th International Conference on Micro Electro Mechanical Systems (MEMS)

We demonstrate a novel resonant and nonlinear piezoelectric oscillator design for the manipulation of the turbulent boundary layer on airfoils. A thorough analysis of the system's non-linear dynamics has helped to convert the abrupt, chaotic and irregular response to a desirable smooth hardening response. The high-force actuators realized amplitudes of 500 to 700 μm in the frequency range of 900 to...

article

Dielectric Electroactive Polymer Membrane Actuator with Ring-type Electrode as Driving Component of a Tactile Actuator

Rui Zhu, Ulrike Wallrabe, Matthias C Wapler, Peter Woias, more

Procedia Engineering > 2016 > 168 > C > 1537-1540

We present a driving concept of a tactile actuator based on a dielectric electroactive polymer using a ring-type electrode. This electrode is located around a deflectable membrane. The fabrication process and tests of the tactile actuator including integration into a hydraulic amplifier design are presented proving the concept of the novel actuation. The tactile actuator exhibits a maximum measured...

chapter

Development of a Thermoelectric Nanowire Characterization Platform (TNCP) for Structural and Thermoelectric Investigation of Single Nanowires

Zhi Wang, S. Hoda Moosavi, Michael Kroener, Peter Woias

Thermoelectric Bi₂Te₃ Nanomaterials > Transport Properties Measurement Techniques > 253 - 281

A microfabricated platform for the thermoelectric characterization of nanowires (NWs) is presented. This platform allows measuring all necessary properties on the same single nanowire: the electrical conductivity, the thermal conductivity, and the Seebeck coefficient. Besides this, the design based on a silicon‐on‐insulator wafer, with a 10 or 20 µm thin device layer, allows for additional structural...

chapter

Power management strategies in self-sufficient sensor nodes

Philipp Mehne, Michael Kroner, Peter Woias

2015 IEEE 12th International Multi-Conference on Systems, Signals & Devices (SSD15) > 1 - 4

2015 12th International Multi-Conference on Systems, Signals & Devices (SSD)

Wireless sensor nodes, powered from energy harvesting generators using available ambient power sources, need a sophisticated power management to optimally budget the scarcely available energy. By that, the reliability, the functionality, and availability of these nodes are increased. The decisions of the power management can either be based on a simple energy income and storage level knowledge, or...

article

Novel approach to dynamic knee laxity measurement using capacitive strain gauges

Martin Zens, Philipp Niemeyer, Anke Bernstein, Matthias J. Feucht, more

Knee Surgery, Sports Traumatology, Arthroscopy > 2015 > 23 > 10 > 2868-2875

Purpose Knee joint laxities are observed in patients after severe trauma to the joint, resulting in ligament tears. Specifically, injuries to the anterior cruciate ligament may cause a significant instability. The degree of these laxities is essential in diagnostics and may affect which treatment option is suggested. Methods Polydimethylsiloxane (PDMS) strain gauges are proposed as a non-invasive,...

article

Mechanical tensile properties of the anterolateral ligament

Martin Zens, Matthias J Feucht, Johannes Ruhhammer, Anke Bernstein, more

Journal of Experimental Orthopaedics > 2015 > 2 > 1 > 1-7

Background In a noticeable percentage of patients anterolateral rotational instabilities (ALRI) remain after an isolated ACL reconstruction. Those instabilities may occur due to an insufficiently directed damage of anterolateral structures that is often associated with ACL ruptures. Recent publications describe an anatomical structure, termed the anterolateral ligament (ALL), and suggest that...

article

Cost Effective MEMS Fabrication of a Thermoelectric Nanowire Characterization Platform (TNCP)

S. Hoda Moosavi, Michael Kroener, Peter Woias

Procedia Engineering > 2015 > 120 > C > 210-214

To decrease the cleanroom requirement of a MEMS chip fabrication, Nd:YAG laser machining is integrated into silicon micromachining. However, to get a smooth surface the laser parameters must be chosen carefully, and a subsequent wet chemical etching treatment of the surface is essential.The process is used to fabricate a Thermoelectric Nanowire Characterization Platform (TNCP). Our TNCPs are designed...

article

Design and Characterization of Micro Thermoelectric Cross-Plane Generators With Electroplated ${\rm Bi}_{2}{\rm Te}_{3}$ , ${\rm Sb}_{x}{\rm Te}_{y}$ , and Reflow Soldering

Reinhard Roth, Raimar Rostek, Keith Cobry, Christian Kohler, more

Journal of Microelectromechanical Systems > 2014 > 23 > 4 > 961 - 971

We demonstrate and discuss the fabrication of cross-plane microthermoelectric generators with electrochemically deposited thermoelectric materials. A new process based on two layers of photoresist is presented to deposit the legs on the final substrate. The n-type

${\rm Bi}_{2}{\rm Te}_{3}$

, Cu, and p-type

${\rm Sb}_{x}{\rm Te}_{y}$

are integrated into the generator. The deposition of antimony...

article

Magnetic sensor for arterial distension and blood pressure monitoring

Johannes Ruhhammer, Tamara Herbstritt, Dominic Ruh, Katharina Foerster, more

Biomedical Microdevices > 2014 > 16 > 6 > 815-827

A novel sensor for measuring arterial distension, pulse and pressure waveform is developed and evaluated. The system consists of a magnetic sensor which is applied and fixed to arterial vessels without any blood vessel constriction, hence avoiding stenosis. The measurement principle could be validated by in vitro experiments on silicone tubes, and by in vivo experiments in an animal model, thereby...

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INFONA - science communication portal

Search results for: Peter Woias

Heat Transfer Modeling of Confined Bubble Evaporation in a Microchannel

Analysis of impedance data from bubble flow in a glass/SU8 microfluidic device with on-channel sensors

Complete Thermoelectric Characterization of PEDOT:PSS Thin Films with a Novel ZT Test Chip Platform

Laser rapid-prototyping and modular packaging of chip-based microreactors for direct fluorination reactions

Optimized detector for closed-loop devices for neurostimulation

The deformable valve pump (DVP)

Coupled piezoelectric nonlinear transduction array for turbulence manipulation

Parametric modeling and experimental characterization of a nonlinear resonant piezoelectric actuator designed for turbulence manipulation

Cost effective MEMS fabrication of a nanowire characterization platform with solder coated electrodes

Surface effects on thermoelectric properties of metallic and semiconducting nanowires

Theoretical and Experimental Investigations of Convective Micromixers and Microreactors for Chemical Reactions

Design and optimization of nonlinear oscillators for drag reduction on airfoils

Dielectric Electroactive Polymer Membrane Actuator with Ring-type Electrode as Driving Component of a Tactile Actuator

Development of a Thermoelectric Nanowire Characterization Platform (TNCP) for Structural and Thermoelectric Investigation of Single Nanowires

Power management strategies in self-sufficient sensor nodes

Novel approach to dynamic knee laxity measurement using capacitive strain gauges

Mechanical tensile properties of the anterolateral ligament

Cost Effective MEMS Fabrication of a Thermoelectric Nanowire Characterization Platform (TNCP)

Design and Characterization of Micro Thermoelectric Cross-Plane Generators With Electroplated ${\rm Bi}_{2}{\rm Te}_{3}$ , ${\rm Sb}_{x}{\rm Te}_{y}$ , and Reflow Soldering

Magnetic sensor for arterial distension and blood pressure monitoring

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