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- Chedid, Michel, 1977-
(författare)
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Wearable Systems in Harsh Environments : Realizing New Architectural Concepts
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wearable systems continue to gain new markets by addressing improved performance and lower size, weight and cost. Both civilian and military markets have incorporated wearable technologies to enhance and facilitate user's tasks and activities. A wearable system is a heterogeneous system composed of diverse electronic modules: data processing, input and output modules. The system is constructed to be body-borne and therefore, several constraints are put on wearable systems regarding wearability (size, weight, placement, etc.) and robustness rendering the task of designing wearable systems challenging. In this thesis, an overview of wearable systems was given by discussing definition, technology challenges, market analysis and design methodologies. Main research targeted at network architectures and robustness to environmental stresses and electromagnetic interference (EMI). The network architecture designated the data communication on the intermodule level - topology and infrastructure. A deeper analysis of wearable requirements on the network architecture was made and a new architecture is proposed based on DC power line communication network (DC-PLC). In addition, wired data communication was compared to wireless data communication by introducing statistical communication model and looking at multiple design attributes: power efficiency, scalability, and wearability.The included papers focused on wearable systems related issues including analysis of present situation, environmental and electrical robustness studies, theoretical and computer aided modelling, and experimental testing to demonstrate new wearable architectural concepts. A roadmap was given by examining the past and predicting the future of wearable systems in terms of technology, market, and architecture. However, the roadmap was updated within this thesis to include new market growth figures that proved to be far less than was predicted in 2004. User and application environmental requirements to be applied on future wearable systems were identified. A procedure is presented to address EMI and evaluated solutions in wearable application through modelling and simulation. Environmental robustness and wearability of wearable systems in general, and washability and conductive textile in particular are investigated. A measurement-based methodology to model electrical properties of conductive textile when subjected to washing was given.Employing a wired data communication network was found to be more appropriate for wearable systems than wireless networks when prioritizing power efficiency. The wearability and scalability of the wired networks was enhanced through conductive textile and DC-PLC, respectively. A basic wearable application was built to demonstrate the suitability of DC-PLC communication with conductive textile as infrastructure. The conductive textile based on metal filament showed better mechanical robustness than metal plated conductive textile. A more advanced wearable demonstrator, where DC-PLC network was implemented using transceivers, further strengthened the proposed wearable architecture. Based on the overview, the theoretical, modelling and experimental work, a possible approach of designing wearable systems that met several contradicting requirements was given.
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| 2. |
- Unander, Tomas
(författare)
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Characterization of Low Cost Printed Sensors for Smart Packaging
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Currently there are very significant interests in printed electronics in the world. The possibility to produce electronics in a roll to roll printing process will considerably reduce the cost of the electronic devices. However, these new devices will most probably not replace the traditional silicon based electronics, but will be a complement in low cost applications such as in intelligent packages and other printable media. One interesting area is printable low cost sensors that add value to packages. In this thesis a study of the performance of low cost sensors is presented. The sensors were fabricated using commercial printing processes used in the graphical printing business. The sensors were characterized and evaluated for the intended application. The evaluated sensors were moisture sensing sensor solutions and touch sensitive sensor solutions. A printable touch sensitive sensor solution is presented where the sensor is incorporated into a high quality image such as in point of sales displays. The sensor solution showed good touch sensitivity at a variety of humidity levels. Four printed moisture sensor concepts are presented and characterized. Firstly, a moisture sensor that shows good correlation to the moisture content of cellulose based substrates. Secondly, a sensor that measures the relative humidity in the air, the sensor has a measuring accuracy of 0.22% at high relative humidity levels. Thirdly, a moisture sensor that utilizes unsintered silver nano-particles to measure the relative humidity in the air, the sensor has a linear response at very low relative humidity levels. And fourth, an action activated energy cell that provides power when activated by moisture. A concept of remote moisture sensing that utilizes ordinary low cost RFID tags has also been presented and characterized. The remote sensor solution works both with passive and semi-passive RFID systems. The study shows that it is possible to manufacture low cost sensors in commercial printing processes.
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| 3. |
- Johansson, Christian, 1972-
(författare)
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High frequency electronic packaging and components : characterization, simulation, materials and processing
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electronic packaging continues to move towards improved performance and lower cost. Requirements of higher performance, reduced size, weight and cost of both high density interconnects and high frequency devices have led to the search for new materials, material combinations, methods, processes and production equipment. Efficient technologies for producing high density interconnects, circuits for high frequency applications but also integrated packaging solutions for electrical and optical interconnects are looked for. Of emerging interest are methods and materials for ultra low cost printing of active components such as diodes and transistors. Large area panel processing (LAP) and sequential build-up technologies, using an UV-excimer projection lithography equipment and a photo-patternable ORMOCER® dielectric, is presented. The novel large area processing equipment enables 5 μm resolution patterning of surfaces up to a size of 610 mm x 610 mm. Large area panel processing enables miniaturized low cost & high performance electronics & photonics packaging. The advanced ORMOCER® dielectric and optical materials allow low temperature processing on low cost polymer substrates with low temperature stability such as FR4. Partitioning between cheap standard (lower) density interconnect in PCB substrates and high density interconnect in the upper thin film layers is possible in order to reduce the number of metal layers and arrive at an optimal performance cost ratio for specific applications. A demonstrator composed of four sequentially build-up dielectric layers have been deposited on a low cost FR4 epoxy substrate intended for high frequency applications. The dielectric layers consist of a photo-patternable ORMOCER® and the intermediate metal layers of sputtered Cu. The UV-patterning was performed with the LAP projection lithography equipment. The produced microstrip lines, ring resonators, vias, stacked capacitors and filters have been characterized at frequencies from 1 GHz to 40 GHz showing the potential of the new dielectric material for microwave applications. The investigation of the material properties were performed with a network analyzer where specially designed structures had been made for the characterization. Some of the measurements at high frequencies were also evaluated and compared with simulations. The measured results showed good agreement with the simulated response. The experimentally obtained high frequency properties of εr ≈ 3.05 and tan(δ) ≈ 0.024 at 10 GHz - 40 GHz would be sufficient for many applications. The dielectric properties of an electronics grade silicone elastomer have been investigated in the frequency intervals 0.1 Hz to 1 MHz and 7 GHz to 18 GHz. The low frequency measurements were performed with a dielectric spectrometer. The results are discussed in terms of performance and usefulness of the material in electronic packaging. The permittivity at room temperature in the frequency range 7 GHz - 18 GHz varied between 2.75 to 2.8 and the loss tangent between 0.018 to 0.033. The loss tangent in the GHz region at room temperature was considerably higher than in the Hz – MHz region most probably due to the activation of the inherent alpha relaxation in the material when reaching the GHz-range. A stepped impedance filter has been realized by changing the dielectric material, i.e. the permittivity instead of modifying the line width. It has been shown that the technology can offer alternatives to the standard approach and also that it is feasible to arrive at a denser packaging by combining low and high permittivity materials. The practical limit of the permittivity ratio is dependent on both available materials and on processability of these materials. The useful range of impedance ratios can be further increased by simultaneously using the ‘standard stepped impedance approach’ and the ‘variable dielectric approach’. A novel rectifying device has been realized by screen printing a silicon powder composite with the intention to use a low temperature low cost manufacturing method. Rectification at frequencies up to 1 MHz has been demonstrated but so far with a too high series resistance to be practically useful. With optimization of the device and composite concept, low temperature, ultra-low cost high speed printing of e.g. high frequency diodes on any substrate, may be viable.
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