Elssner M.,Fraunhofer Institute for Microelectronic Circuits and Systems |
Vogt H.,University of Duisburg - Essen
This paper analyzes relevant failure mechanisms for microbolometer thermal imager sensors that are assembled with a small size and low cost chip scale package. The analyses focus on device specific elements like the bolometer sensor structures, the longtime stability of the sensor and its performance, and the stability of the hermetic chip scale package. Executed reliability tests showed a high reliability of the sensor and the package without hard failures. The package survived harsh environmental accelerated stress tests and showed only a slight reduction of the shear strength through void formation and small cracks within the lead frame that could be verified through FEM simulations. The stress on the bolometers is investigated by thermomechanical FEM simulations. Executed reliability tests showed no enlargement in the number of defect pixel. The sensor performance showed a longtime drift and temperature dependence through outgassing processes inside the package leading to a significant performance reduction. Thus this effect is investigated more closely and possible countermeasures are proposed. © 2015 Elsevier Ltd. Source
Elssner M.,Fraunhofer Institute for Microelectronic Circuits and Systems
This paper presents an innovative and effective method of measuring the internal vacuum quality of un-cooled micro bolometer thermal imager sensors where the bolometer sensor elements themselves are used for vacuum measurement. A feasible thermal calculation model using an extended Fourier's Law is presented which is integrated in thermal FEM simulations. Experimental results correlating with FEM simulations prove the feasibility of this method. A measuring range to pressures as low as 5 × 10-3 mbar was achieved that fully covers the needed range where the internal package pressure is leading to performance losses of the IRFPA. The vacuum quality evaluation method supported by a developed temperature compensation method is showing a high repetitive accuracy with a remaining mean failure of 0.2%. Without the need to integrate additional pressure sensors this method reduces costs and chip area and it is fast and highly accurate. Therefore, it can be used for stationary test systems as well as in mobile infrared camera systems. © 2014 Elsevier Ltd. All rights reserved. Source
Rosman C.,University of Mainz |
Pierrat S.,Fraunhofer Institute for Microelectronic Circuits and Systems |
Henkel A.,University of Mainz |
Tarantola M.,Max Planck Institute for Dynamics and Self-Organization |
And 4 more authors.
Toxicological effects of nanoparticles are associated with their internalization into cells. Hence, there is a strong need for techniques revealing the interaction between particles and cells as well as quantifying the uptake at the same time. For that reason, herein optical dark-field microscopy is used in conjunction with transmission electron microscopy to investigate the uptake of gold nanoparticles into epithelial cells with respect to shape, stabilizing agent, and surface charge. The number of internalized particles is strongly dependent on the stabilizing agent, but not on the particle shape. A test of metabolic activity shows no direct correlation with the number of internalized particles. Therefore, particle properties besides coating and shape are suspected to contribute to the observed toxicity. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source
Klauke S.,University of Marburg |
Goertz M.,Fraunhofer Institute for Microelectronic Circuits and Systems |
Rein S.,Thomas Recording GmbH |
Hoehl D.,Thomas Recording GmbH |
And 5 more authors.
Investigative Ophthalmology and Visual Science
PURPOSE. Electrical stimulation of retinal neurons has been shown to be a feasible way to elicit visual percepts in patients blind from retinal degenerations. The EPIRET3 retinal implant is the first completely wireless intraocular implant for epiretinal stimulation. Stimulation tests have been performed during a clinical trial that was carried out at the eye clinics of Aachen and Essen to evaluate the safety and the efficacy of the implant. METHODS. Six legally blind retinitis pigmentosa patients were included in the study. In accordance with the regulations laid down in the study protocol, three 1-hour perceptual tests for each subject were performed within 4 weeks of surgery. Stimuli were charge-balanced square current pulses of various durations and current amplitudes. RESULTS. All subjects reported visual percepts as a result of electrical stimulation by the implant. Thresholds for eliciting visual percepts varied between them but were below the safety limits of electrical stimulation. Stimulation success depended stronger on pulse duration than on current amplitude or total charge delivered. Subjects were able to discriminate between stimulation patterns of different orientations or at different locations of the electrode array. CONCLUSIONS. The EPIRET3 system is suitable to elicit visual percepts in blind retinitis pigmentosa patients. © 2011 The Association for Research in Vision and Ophthalmology, Inc. Source
« Toyota doubles the electric range in the new version of Prius PHEV with 8.8 kWh pack | Main | Primus Green Energy methanol plant project slated for 2017 in the Marcellus Region » Engineers from Saarland University are developing intelligent motor systems that function without the need for additional sensors. By essentially transforming the motor itself into a sensor, the team led by Professor Matthias Nienhaus is creating smart motors that can tell whether they are still running smoothly, can communicate and interact with other motors and can be efficiently controlled. By using data collected from the motor while it is operating, the researchers are able to calculate quantities that in other systems would need to be measured by additional sensors. Further, they are teaching the drive how to make use of this knowledge. Gathering data from the motor while it is operating normally is particularly valuable for the research team; the more motor data they have, the more efficiently they can control the motor. The engineers analyze the motor data to identify those signal patterns that can be used to infer something about the current status of the motor or to flag up changes arising from a malfunction or from wear. The team is developing mathematical models that simulate the various motor states, fault levels and degrees of wear. The results are fed into a microcontroller. If a certain signal changes, the controller can identify the underlying fault or error and respond accordingly. These sentient motors can be linked together via a network operating system to form an integrated complex that open up numerous opportunities in the fields of maintenance, quality assurance and production. It is also conceivable that a system could be designed in which one motor automatically takes over if one of the other motors fails. In order to gather data from the motor, Nienhaus and his team carefully monitor the precise distribution of the magnetic field strength in the motor. An electromagnetic field is generated when electric current flows through the coils located within the outer ring of rotating permanent magnets. The researchers record how this magnetic field changes when the motor rotates. This data can then be used to compute the position of the rotor and to draw other inferences about the status of the motor, which allows the motor to be controlled efficiently and error states to be detected reliably. Nienhaus is currently testing a number of different methodologies to determine those best suited to acquiring data from the motor. This work is being carried out as part of the project “Modular sensor systems for real-time process control and smart state monitoring” (MoSeS-Pro). The research team is looking to identify which motor speed range generates the best data and which type of motor is best suited for this type of application. The MoSeS-Pro project is being funded by the Federal Ministry of Education and Research (BMBF). The goal of the MoSeS-Pro project is to develop a suite of hardware and software modules with which it will be easier to develop sensor systems for monitoring and controlling drives and positioning systems, paving the way for fast and precise manufacturing processes that can be monitored and adjusted in real time. The project is being carried with the support of the associated partners Festo AG (Rohrbach plant) and Bosch Rexroth AG (Homburg plant) and the direct project partners Sensitec GmbH, Lenord, Bauer & Co. GmbH, ESR Dipl.-Ing. Pollmeier GmbH and CANWAY Technology GmbH. In addition to ZeMA, research partners in the MoSeS-Pro project are the Fraunhofer Institute for Microelectronic Circuits and Systems (IMS) and the Department of Integrated Sensor Systems at Kaiserslautern University of Technology. The research work has received financial support totalling €3.1 million (US$3.5 million) as part of the BMBF funding programme “Sensor-based electronic systems for Industry 4.0 applications (SElekt I4.0)”, which is being managed by the project management agency VDI/VDE-IT. Around €540,000 (US$603,000) in funding has been allocated to Saarland University. The researchers are currently working with project partners to study and test a number of different procedural methods. The ultimate goal is to make manufacturing processes more cost-effective and flexible and to enable machinery and equipment to be continuously monitored for faults or signs of wear. The project will be on show at Hannover Messe from 25-29 April, where the team will be exhibiting at the Saarland Research and Innovation Stand in Hall 2, Stand B46.