Thermal and mechanical characterization of high-performance polymer fabrics for applications in wearable devices

With advances in fexible and wearable device technology, thermal regulation will become increasingly important. Fabrics and substrates used for such applications will be required to efectively spread any heat generated in the devices to ensure user comfort and safety, while also preventing overheating of the electronic components. Commercial fabrics consisting of ultra-high molecular weight polyethylene (UHMW-PE) fbers are currently used in personal body armor and sports gear owing to their high strength, durability, and abrasion resistance. In addition to superior mechanical properties, UHMW-PE fbers exhibit very high axial thermal conductivity due to a high degree of polymer chain orientation. However, these materials have not been widely explored for thermal management applications in fexible and wearable devices. Assessment of their suitability for such applications requires characterization of the thermal and mechanical properties of UHMW-PE in the fabric form that will ultimately be used to construct heat spreading materials. Here, we use advanced techniques to characterize the thermal and mechanical properties of UHMW-PE fabrics, as well as other conventional fexible materials and fabrics. An infrared microscopy-based approach measures the efective in-plane thermal conductivity, while an ASTM-based bend testing method quantifes the bending stifness. We also characterize the efective thermal behavior of fabrics when subjected to creasing and thermal annealing to assess their reliability for relevant practical engineering applications. Fabrics consisting of UHMW-PE fbers have signifcantly higher thermal conductivities than the benchmark conventional materials while possessing good mechanical fexibility, thereby showcasing great potential as substrates for fexible and wearable heat spreading application

Review of energy harvesting techniques and applications for microelectronics

The trends in technology allow the decrease in both size and power consumption of complex digital systems. This decrease in size and power gives rise to new paradigms of computing and use of electronics, with many small devices working collaboratively or at least with strong communication capabilities. Examples of these new paradigms are wearable devices and wireless sensor networks. Currently, these devices are powered by batteries. However, batteries present several disadvantages: the need to either replace or recharge them periodically and their big size and weight compared to high technology electronics. One possibility to overcome these power limitations is to extract (harvest) energy from the environment to either recharge a battery, or even to directly power the electronic device. This paper presents several methods to design an energy harvesting device depending on the type of energy available.Peer Reviewe

The design of personal ambient displays

Thesis (S.M.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1999.Includes bibliographical references (leaves 58-59).The goal of this thesis is to investigate the design of personal ambient displays. These are small, physical devices worn to display information to a person in a subtle, persistent, and private manner. They can be small enough to be carried in a pocket, worn as a watch, or even adorned like jewelry. In my implementations, information is displayed solely through tactile modalities such as thermal change (heating and cooling), movement (shifting and vibration), and change of shape (expanding, contracting, and deformation). Using a tactile display allows information to be kept private and reduces the chance of overloading primary visual and auditory activities. The display can remain ambient, transmitting information in the background of a person's perception through simple, physical means. The specific focus of this thesis is to create a number of these tactile displays, to identify and implement applications they can serve, and to evaluate aspects of their effectiveness. I have created a group of small, wireless objects that can warm up and cool down or gently move or shift. Users can reconfigure each display so that information sources like stock data or the activity of people on the internet are mapped to these different tactile modalities. Furthermore, in this thesis I consider the implications that human perception have on the design of these displays and examine potential application areas for further implementations.Craig Alexander Wisneski.S.M

Interface diffuse : conception, développement et évaluation d'un nouveau paradigme d'interaction humain-ordinateur porté

Introduction -- Revue de littérature sur les interfaces humain-ordinateur porté -- Problématique liée aux interactions humain-ordinateur porté -- Méthodologie de l'étude expérimentale -- Conception et développement d'un prototype d'ordinateur porté et des interfaces diffuses associées -- Résultats de l'étude expérimentale et discussion -- Conclusion