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Sandner T.,Fraunhofer Institute for Photonic Microsystems
Optics InfoBase Conference Papers | Year: 2016

Micro scanning mirrors play an important role in various optical applications for highly miniaturized, reliable and cost efficient scanning systems like compact laser projection displays, endoscopic and medical imaging systems or LIDAR 3D-cameras. We give an overview about different MEMS scanner technologies including bi-resonant, linear raster scanning and 2D-vectorial scanning systems. Finally we present examples of industrial applications including miniaturized FTIRpectrometers, tunable laser sources, high power scanner for laser surgery and fast raster scanning devices for medical imaging. © OSA 2016.

Grahmann J.,Fraunhofer Institute for Photonic Microsystems
Optics InfoBase Conference Papers | Year: 2016

The combination of an external cavity quantum cascade laser with a MOEMS based scanning diffraction grating of 1 kHz resonance frequency and its electrostatic drive is described. The characteristics of the MOEMS scan module as well as of the entire μECQCL like spectral line width and wavelength eproducibility are shown. Finally the μEC-QCL is used as light source for real time spectroscopic sensing of polystyrene and carbon monoxide. © OSA 2016.

News Article | November 2, 2015
Site: phys.org

Large public building complexes, such as exhibition halls, airports, shopping centers or museums, as well as hospitals and public authority buildings are sometimes like a maze. Arrows, maps and signs are supposed to make it clearer. But right when you enter the building for the first time, it is often very laborious and complicated to follow them through the maze of corridors, hallways, rooms and floors. Classic GPS-based navigation apps do not work in enclosed spaces, because the satellite signals are sometimes significantly disrupted by walls and ceilings. Researchers at the Fraunhofer Institute for Photonic Microsystems IPMS in Dresden, Germany have found a way to use smartphones for navigation inside buildings too. For this they rely on WLAN: With local radio networks, the researchers locate smartphones indoor to within about two meters. To determine the position, the software evaluates the signal strength of the WLAN spots. The app, which was originally developed for use in hospitals, is based on the Android mobile phone operating system. When starting the app, different targets can be selected – for example, examination rooms, patient rooms, cafeterias and restrooms or mobile inventory, such as beds and wheelchairs. As with navigation devices in cars, the user sees the building plan in a two-dimensional bird's-eye view. The target and current position are marked with dots and the shortest route is shown on the map. If the user moves, so does his position point. If the destination is outside the screen or on a different floor, arrows show the way. The hospital provides the material for the desired maps. Emergency evacuation plans can often be used as a template. "We can bring any large map sharply and without any annoying delays onto every screen," says Christian Scheibner from the Department of Wireless Microsystems of the IPMS. The app receives all the necessary data from the user's server. Thanks to open interfaces, the positioning and navigation algorithms as well as the graphical representations can be installed simply and straightforwardly in customers' applications. In the apps of trade fairs organizers, for example, which often lack maps, route planning or position determination. "Hospitals have caught up considerably in terms of wireless hot spots in recent years. For example, there are more and more medical devices which are equipped with WLAN and which can be used for indoor navigation" says the hardware and software developer Scheibner. The software works in all indoor areas where WLAN is available. The navigation destinations can be linked with other information. As a result, a user in a shopping mall, for example, will find his way directly and quickly to the rack with special deals. A demo system of the app is running successfully at the IPMS. "Interested parties can try it on site at the Institute at any time," says Scheibner. The technology was developed on behalf of an infrastructure outfitter for hospitals. They are being presented at the MEDICA international trade fair in Dusseldorf from November 16 to 19, 2015. Explore further: WLAN leads the way

News Article | January 8, 2016
Site: phys.org

Scanning electron micrograph of a sample of V-like nanoscopic electrostatic drives actuator. (a) Two cuts are made with a focused ion beam after sacrificial layer releases etch. (b-e) Cross sections that detail the NED elementary actuator cell. Credit: Fraunhofer Institute for Photonic Microsystems IPMS Researchers from the Mesoscopic Actuators and Systems (MESYS) project group at Fraunhofer Institute for Photonic Microsystems IPMS have been developing novel electrostatic microactuators, so-called nanoscopic electrostatic drives (NED), for three years. Now, this highly interesting scientific approach is being introduced to the public for the first time in an article appearing in the Nature Communications journal. Prof. Dr. Harald Schenk, Director of the Fraunhofer IPMS and Professor of Micro and Nanosystems at Brandenburg Technical University Cottbus-Senftenberg (BTU), is delighted, "We are very proud of the appreciation of our work and our results being published in this prestigious professional journal. After three years of basic research, we were able to demonstrate a completely new actuatory principle." The CMOS compatible actuator class technology developed by MESYS solves fundamental problems of electrostatic actuators. Previously, deflection was very limited due to the so-called pull-in-effects and the movement of conventional actuators was restricted to approximately 33 percent of the electrode spacing. This problem has now been solved. Group Leader Holger Conrad explains, "By means of suitable lever mechanisms, deflections which are much greater than the electrode separations are now available. Therefore, nanometer-small electrode spacings can be deployed, enabling actuators to make use of the enormous force of electrostatic fields." The patented actuator class can greatly improve the performance of microsystems such as capacitive ultrasonic transducers, tilting micro-mirrors and microvalves in the future. In addition, the actuator class provides completely new design solutions for microsystems such as micropumps, MEMS loud speakers or micro positioning systems. Conrad concludes, "Our vision is to develop electrostatic actuators with extremely small gap distances for high deflections at moderate control voltages. We want to extend the developed principle to enable in-plane movement and believe that the new electrostatic bender actuators could perspectively replace or supplement piezoelectric or electrostrictive materials as well. This would then allow for RoHs-compliant bender actuators." The article was published on Nature Communications and is freely available as Open Access: Explore further: New chip provides better bioimaging performance

Paler S.,Fraunhofer Institute for Photonic Microsystems | Wolff M.,TU Dresden | Fischer W.-J.,Fraunhofer Institute for Photonic Microsystems
Physiological Measurement | Year: 2012

Obesity and nutrition-related diseases are currently growing challenges for medicine. A precise and timesaving method for food intake monitoring is needed. For this purpose, an approach based on the classification of sounds produced during food intake is presented. Sounds are recorded non-invasively by miniature microphones in the outer ear canal. A database of 51 participants eating seven types of food and consuming one drink has been developed for algorithm development and model training. The database is labeled manually using a protocol with introductions for annotation. The annotation procedure is evaluated using Cohen's kappa coefficient. The food intake activity is detected by the comparison of the signal energy of in-ear sounds to environmental sounds recorded by a reference microphone. Hidden Markov models are used for the recognition of single chew or swallowing events. Intake cycles are modeled as event sequences in finite-state grammars. Classification of consumed food is realized by a finite-state grammar decoder based on the Viterbi algorithm. We achieved a detection accuracy of 83% and a food classification accuracy of 79% on a test set of 10% of all records. Our approach faces the need of monitoring the time and occurrence of eating. With differentiation of consumed food, a first step toward the goal of meal weight estimation is taken. © 2012 Institute of Physics and Engineering in Medicine.

Weder A.,Fraunhofer Institute for Photonic Microsystems
Proceedings - 2nd International Conference on Computational Intelligence, Communication Systems and Networks, CICSyN 2010 | Year: 2010

In the recent years, Wireless Body Sensor Networks (WBSNs) attracted much attention in the research community. The key to success for WBSNs is the utilization of highly efficient transceivers and the application of intelligent policies to handle the limited (energy) resources. Simulations are a frequently used tool to evaluate different policies and analyze the performance of wireless networks in different configurations. The nRF24L01 is an ultra-low-power transceiver for the 2.4 GHz frequency band which is very well suited to build simple but efficient WBSNs. This work presents a detailed simulation model of the nRF24L01 for MiXiM, a simulation framework for wireless networks. The implementation is focused on tracking the transceiver's energy consumption in operation. The presented simulation model is a valuable tool for network designers and implementers when working with the nRF24L01. © 2010 IEEE.

Passler S.,Fraunhofer Institute for Photonic Microsystems | Fischer W.-J.,Fraunhofer Institute for Photonic Microsystems
Proceedings - 2011 7th International Conference on Intelligent Environments, IE 2011 | Year: 2011

A method for non-invasive monitoring of human food intake behavior and long-term dietary protocol has been developed by the sole use of chewing and swallowing sound sensors. A novel sensor system has been built containing an in-ear microphone and a reference microphone integrated in a hearing aid case in order to record chewing and swallowing sounds in the ear canal and environmental noise, respectively. Using manual labeled records of the food intake sounds of 40 participants we developed an algorithm to detect food intake activity in sound data. Comparison between sounds from both microphones enables the discrimination between internal and external sounds. © 2011 IEEE.

Gay N.,Fraunhofer Institute for Photonic Microsystems | Fischer W.-J.,Fraunhofer Institute for Photonic Microsystems
Proceedings of IEEE Sensors | Year: 2010

This paper deals with the design and implementation of flexible, fully integrated sensor motes for ubiquitous sensor networks based on a established, long-range RFID technology. The battery-less mote is made up of a single-chip solution incorporating a microwave RFID-front-end, an 8-bit microcontroller, a low-power temperature sensor, a reconfigurable sensor interface, a 10-bit SAR ADC, a full-fledged I 2C digital interface and non-volatile memory for program and sensor data. Overall power consumption lies under 7μW at a readout distance of 3 m. The temperature sensor works from -20 up to +60°C with a precision of +/-0.5°C and 16 bits resolution. A fully-passive demonstration system with external commercial sensors including pressure, humidity and acceleration sensors was implemented and tested. ©2010 IEEE.

Polakowski P.,Fraunhofer Institute for Photonic Microsystems | Muller J.,Fraunhofer Institute for Photonic Microsystems
Applied Physics Letters | Year: 2015

We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4-20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization Pr of up to 10 μC cm-2 as well as a read/write endurance of 1.6 × 105 cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems. © 2015 AIP Publishing LLC.

Gruger H.,Fraunhofer Institute for Photonic Microsystems
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Over the past decades zoom lenses have become an important type of objective. Due to their ability to dynamically change magnification or field angle they are being used in many fields of application. Most zoom lenses consist of a number of lenses or lens groups. The magnification can be changed by axial shifting some of these lens groups with a more or less complicated moving function. However, in principle it should be possible to construct zoom lenses that do not rely on the movement of some of its components. Instead, the change in magnification is achieved by changing the optical power of at least two lenses within the system (optical power zoom - OPZ). Moreover, for broadband applications it is highly favorable to use mirrors instead of lenses due to the absence of chromatic aberrations. Based on a "Schiefspiegler" approach an all-reflective OPZ objective with a zoom power of three consisting of four mirrors has been designed. Two mirrors are assumed to have a variable radius of curvature for changing optical power. During aberration correction special consideration has been given to the reduction of field curvature, since the optical power change strongly influences field curvature for different zoom positions. The simulation shows adequate image quality for photographic applications over the whole zooming range. For the realization of such an OPZ objective deformable mirrors with a comparatively large stroke are needed. Before starting a complex development of such devices three setups with different fixed focal lengths were built to prove and evaluate the concept for digital imaging. © 2015 SPIE.

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