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Jedermann R.,Institute for Microsensors | Jedermann R.,Microsystems Center Bremen | Potsch T.,University of Bremen | Potsch T.,Bremen Research Cluster for Dynamics in Logistics LogDynamics | And 2 more authors.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2014

Remote measurement of product core temperature is an important prerequisite to improve the cool chain of food products and reduce losses. This paper examines and shows possible solutions to technical challenges that still hinder practical applications of wireless sensor networks in the field of food transport supervision. The high signal attenuation by water-containing products limits the communication range to less than 0.5m for the commonly used 2.4GHz radio chips. By theoretical analysis of the dependency of signal attenuation on the operating frequency, we show that the signal attenuation can be largely reduced by the use of 433MHz or 866MHz devices, but forwarding of messages over multiple hops inside a sensor network is mostly unavoidable to guarantee full coverage of a packed container. Communication protocols have to provide compatibility with widely accepted standards for integration into the global Internet, which has been achieved by programming an implementation of the constrained application protocol for wireless sensor nodes and integrating into IPv6-based networks. The sensor's battery lifetime can be extended by optimizing communication protocols and by in-network preprocessing of the sensor data. The feasibility of remote freight supervision was demonstrated by our full-scale 'Intelligent Container' prototype. © 2014 The Author(s) Published by the Royal Society.


Lang W.,Institute for Microsensors | Lang W.,University of Bremen | Jakobs F.,Institute for Microsensors | Tolstosheeva E.,Institute for Microsensors | And 5 more authors.
Sensors and Actuators, A: Physical | Year: 2011

Ubiquitous computing is about to become part of our everyday lives by integrating hundreds of "invisible" to us computing devices in our environment, so that they can unobtrusively and constantly assist us. This will imply more and smaller "invisible" sensors, homogeneously distributed and at the same time densely packed in host materials, responding to various stimuli and immediately delivering information. In order to reach this aim, the embedded sensors should be integrated within the host material, heading towards sensorial materials. The first step is to omit all parts that are not needed for the sensorial task and to find new solutions for a gentle integration. This is what we call function scale integration. The paper discusses sensor embedding in the human hand as an example of integration in nature, new technological applications and main challenges associated with this approach. © 2011 Elsevier B.V.


Kahali Moghaddam M.,Institute for Microsensors | Breede A.,Faserinstitut Bremen E.V. | Chaloupka A.,Fraunhofer Institute for Chemical Technology | Bodecker A.,Institute for Microsensors | And 4 more authors.
Sensors and Actuators, A: Physical | Year: 2016

In this study, microscale interdigital capacitive sensors are designed, fabricated and embedded in glass fiber composite for real-time cure monitoring of resin. The microscale interdigital capacitive sensor offers great advantages due to its miniaturized size, high flexibility and high temperature stability. Most importantly, after integration, due to the small footprint and only 5 μm thickness, the embedded sensor minimally downgrades the composite mechanical properties. Apart from all these merits, the substrate foil is perforated to provide an opportunity for the resin to go through the substrate and bridge it. The sensor consists of two interdigitated arrays. There are two different sensor designs, which offer 900 and 450 electrodes in arrays. The electrodes are made out of tantalum and are fully insulated with about 50 nm tantalum oxide. Therefore, it is possible to embed the sensor even in conductive fibers, e.g. carbon, and to use the sensor out of the Cleanroom without getting contaminated with conductive particles to shortcut the arrays. Polyimide is chosen for the substrate of the sensor. This specific polymer has excellent flexibility and its geometry stays unchanged even at high temperature. The Dielectric Analysis (DEA) measurement proves the effective and real-time tracking of resin polymerization during laminate production. © 2016 Elsevier B.V. All rights reserved.


Sklorz A.,Institute for Microsensors | Lang W.,Institute for Microsensors
Procedia Engineering | Year: 2011

Three sensitivity improvement strategies for non-dispersive-infrared (NDIR) ethylene gas detectors were defined and examined: the application of low-cost Fresnel lenses, usage of a conically shaped measurement chamber and a simple digital signal processing lead to a seven times better IR-radiation efficiency compared to a system configuration without consideration of these methods. The approaches don't affect IR-detectors, IR-sources or the optical pathway and thus, the methods can be called "passive". It was shown that usage of lock-in amplifiers is not necessary to achieve good sensitivity results and noise equivalent concentrations of about 6 ppmv. © 2011 Published by Elsevier Ltd.


Brinksmeier E.,IWT - Foundation Institute of Materials Engineering | Heinzel C.,IWT - Foundation Institute of Materials Engineering | Wilkens A.,IWT - Foundation Institute of Materials Engineering | Lang W.,Institute for Microsensors | Seedorf T.,Institute for Microsensors
Advanced Engineering Materials | Year: 2010

A different to conventional monitoring systems sensor equipped tools give the possibility to gain information about the process status directly from the contact zone between tool and component to be machined. For example this can be realized by the integration of small temperature sensors into grinding wheels. The transmitting of the process data is performed by a telemetric unit attached to the grinding wheel's core. In this paper, the development of a new thin film thermocouple sensor concept is described. The unique feature of this sensor is the continuous contacting of the thermocouple through the grinding process inherent wear which leads to smearing of the thermoelectric layers and thus forming the measuring junction of a thermocouple. The system was used in OD grinding processes aiming to detect grinding burn and process instabilities. By reducing the volume of the sensors a fast response and high time resolution can be obtained. By thisway, observance of the key parameters of the practical operation as closely as possible to the cutting area is enabled and so observance of process efficiency and tool status independent from workpiece machining conditions can be realized. All sensors used are thermocouples of type K, a combination of Chromel (NiCr) and Alumel (NiAlMnSi) material. The maximum temperature to be measured by this sensor is about 1350 °C, which ensures the applicability in the grinding process. Telemetry components to amplify and send the thermovoltage signals are adjusted to this type of thermocouple. The ability of the set-up to detect thermal influences was demonstrated in grinding processes with a continuously increasing specific material removal rate. The approach serves to measure temperatures between fast sliding surfaces in harsh environments (fluids, high pressure, heat), similar to the grinding process. Therefore their application is not limited to tools but also applicable for other rotating components such as bearings, gears and shafts in powertrains. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Sturm H.,Institute for Microsensors | Brauns E.,Institute for Microsensors | Froehner K.,Institute for Microsensors | Lang W.,Institute for Microsensors | Buchner R.,Danfoss A/S
Proceedings of IEEE Sensors | Year: 2010

A thermoelectric mass flow rate sensor on a 10 μm thick polyimide foil and its integration process on planar as well as non-planar surfaces has been developed. Flow sensors, fabricated by MEMS technology, usually have a height which is directly coupled to the wafer thickness (typically 525 μm or 380 μm). They are not bendable and an integration process is always complex when steps in flow channels have to be avoided. A fabrication process has been developed where the functional layers were removed from the silicon substrate and transferred onto a 10 μm thick polyimide foil. The resulting flexible flow sensor has been integrated on different materials by means of flip chip mounting and tested on its electrical and mechanical characteristics. It could be shown that thermoelectric flow sensors on polymer foils have comparable characteristics to flow sensors on silicon substrates but higher diversity in system integration. ©2010 IEEE.


Sklorz A.,FWBI Friedrich Wilhelm Bessel Institute Forschungsgesellschaft MbH | Schafer A.,Institute for Microsensors | Lang W.,FWBI Friedrich Wilhelm Bessel Institute Forschungsgesellschaft MbH | Lang W.,Institute for Microsensors
Procedia Engineering | Year: 2010

Automated and reliable measurements of low concentrations of ethylene gas in ambience during transport of fruits are of great interest in fruit logistics. Knowledge about the concentration can be used for ripeness and quality prediction as well as for new logistic approaches. Here it makes sense to use non-dispersive-infrared-sensors as autonomous ethylene measurement systems because of their robustness and selectivity. In this paper such a measurement system is presented. It measures ethylene down to 10 ppmv. To overcome sensitivity limitations, the system was additionally combined with an ethylene preconcentrator to increase the system sensitivity down to the ppbv region indirectly by using adsorption effects on graphitized carbon.


Breede A.,Faserinstitut Bremen e.V | Moghaddam M.K.,Institute for Microsensors | Brauner C.,Faserinstitut Bremen e.V | Lang W.,Institute for Microsensors | Herrmann A.S.,Faserinstitut Bremen e.V
Materials Science Forum | Year: 2015

An online monitoring scheme to determine viscosity and permeability for a composite main spar infusion is presented. During the manufacturing process, defects such as dry spots and pores can occur and lead to poor part quality. In this study, dielectric sensors are used to create the information needed to model the process. Several experiments have been carried out to investigate the correlation between the sensors signal and the viscosity and to derivate constitutive equations. The provided data and the derived permeabilities are integrated into a simulation model of a cross section of the composite main spar. As a result, the real permeability can be identified. The knowledge of these parameters is one of the key aspects for a prediction of the resin flow and therefore for an improved process control. © (2015) Trans Tech Publications, Switzerland.


Kibben S.,BIAS Bremen Institute of Applied Beam Technology | Kropp M.,Institute for Microsensors | Dumstorff G.,Institute for Microsensors | Koerdt M.,BIAS Bremen Institute of Applied Beam Technology | And 2 more authors.
Production Engineering | Year: 2013

A concept study for a bend sensor based on a fibre Bragg grating (FBG) and a compact evaluation unit for the investigated type of sensor is presented. For this, two independent measurands, one well known and one novel, are considered. The fibreoptic sensor principle is capable of resolving the radius and the direction of the bend. The measurement data evaluation principle is capable of resolving multiple distributed FBG sensors, which are present in a single fibre at different positions. © 2012 German Academic Society for Production Engineering (WGP).

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