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This work presents a modular approach to the development of strain sensors for large deformations. The proposed method separates the extension and signal transduction mechanisms using a soft, elastomeric transmission and a high-sensitivity microelectromechanical system (MEMS) transducer. By separating the transmission and transduction, they can be optimized independently for application-specific mechanical and electrical performance. This work investigates the potential of this approach for human health monitoring as an implantable cardiac strain sensor for measuring global longitudinal strain (GLS). The durability of the sensor was evaluated by conducting cyclic loading tests over one million cycles, and the results showed negligible drift. To account for hysteresis and frequency-dependent effects, a lumped-parameter model was developed to represent the viscoelastic behavior of the sensor. Multiple model orders were considered and compared using validation and test data sets that mimic physiologically relevant dynamics. Results support the choice of a second-order model, which reduces error by 73% compared to a linear calibration. In addition, we evaluated the suitability of this sensor for the proposed application by demonstrating its ability to operate on compliant, curved surfaces. The effects of friction and boundary conditions are also empirically assessed and discussed.

Information is integral to the engineering design process, and gaining access to design knowledge is critical to effective design decision-making. This paper considers the indexing and retrieval of informal, unstructured information captured from electronic design logbooks. One of the key observations of informal design information is its evolutionary nature over time. While this characteristic makes informal information a rich source for reuse, it also makes it difficult to employ traditional information retrieval (IR) approaches. The work described in this paper is based on a framework developed specifically for the information handling requirements of designers. This manual method for indexing information is adapted to meet the evolutionary nature of design through the development of thesauri for design context. Several approaches to building thesauri are examined, including manual and automated methods. It is found that manual methods provide a high level of IR performance, but also have high overhead requirements. Machine methods, however, may provide a viable, low overhead alternative. [ABSTRACT FROM AUTHOR]