Analysis of failure mechanisms of machine embroidered electrical contacts and solutions for improved reliability

In recent years, a number of research projects and patents have proposed to apply embroidery of conductive yarn to build electric circuits on textile substrates. To contact electronic modules or components to these circuits, embroidery itself was applied as a contacting method. Thereby, the embroidery needle is stitching through a conductive pad on an electronic substrate and is laying the conductive thread over this pad. The yarn and the pad establish an electrical contact. However, until today this contacting technology based on embroidery has not been adopted by the industry since reliability issues during stress were reported by different researchers. Yet, neither these failure phenomena were investigated comprehensively, nor was it attempted to understand their cause. This inhibited potential improvements to make these embroidered contacts reliable. Furthermore, the lack of alternative technologies for a reliable and volume producible contacting of embroidered circuits with electronic components or modules kept embroidered circuits from evolving to actual products. Therefore, this thesis primarily develops an understanding of the contact mechanism underlying embroidered contacts, and develops a theory that explains the failure phenomena. Secondarily the thesis overcomes these reliability issues by improving these contacts and by finding alternatives. The ultimate goal beyond this thesis is a volume producible contacting process. Therefore, this thesis looks mainly at machine embroidered contacts

Who Commits to the Rule of Law? Constrained Government and Foreign Direct Investment in Postcommunist States

Research linking credible commitments to the rule of law in terms of property rights and contract enforcement is a hallmark of recent efforts to explain economic growth and development. However, many postcommunist states have had difficulty making such commitments and spurring growth. Many argue political polarization prevents states from reforming laws and protecting property rights in some countries whereas single-party governance renders state promises incredible in others. I analyze pooled cross-sectional time-series data for twenty-four postcommunist countries and provide evidence effective constraints among elected officials act as democratic commitment mechanisms rendering government policies credible

Democracy, development and the executive presidency in Sri Lanka

This paper examines the developmental causes and consequences of the shift from a parliamentary to a semi-presidential system in Sri Lanka in 1978, examining its provenance, rationale, and its unfolding trajectory. drawing on a wide range of sources, it set out an argument that the executive presidency was born out of an elite impulse to create a more stable, centralised political structure to resist the welfarist electoral pressures that had taken hold in the post-independence period, and to pursue a market-driven model of economic growth. This strategy succeeded in its early years 197801993, when presidents retained legislative control, maintained a strong personal commitment to market reforms, and cultivated alternative sources of legitimacy. In the absence of these factors, the presidency slipped into crisis over 1994-2004 as resistance to elite-led projects of state reform mounted and as the president lost control of the legislature. Since 2005 the presidency has regained its power, but at the cost of abandoning its original rationale and function as a means to recalibrate the elite/mass power relations to facilitate elite-led reform agendas

A communal catalogue reveals Earth's multiscale microbial diversity

Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.Peer reviewe

A communal catalogue reveals Earth’s multiscale microbial diversity

Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity

Modeling embroidered contacts for electronics in textiles

For over a decade, textile circuits have been realized by embroidering conductive yarns onto fabric. Even machine embroidery has been applied. The standard method for connecting these circuits with electronic components has been hand sewing. However, volume production requires the integration of the connection process into the machine embroidery process. For end-user satisfaction and market acceptance, reliability of the contacts is vital. This publication, for the first time, develops a complete theoretical model of the contact mechanism underlying embroidered contacts. Based on this model, potential failure mechanisms are identified. An experimental implementation of the model is developed. To validate the model, test samples of the model and such of the machine-embroidered contacts are exposed to temperature cycles, chosen as an exemplary reliability test. In addition, reliability test results of four encapsulation technologies are presented

Fundamental analysis of embroidered contacts for electronics in textiles

Integration of electronics into textiles has been a growing topic in recent years. However, a reliable contact between conductive textile structures and electronics modules is still an insufficiently solved problem. One approach is to embroider the conductive textile right to the electronics. This research describes the constitution of the electrical contact and explains resistance changes during temperature variation. This is done by studying the thermo-mechanical and electrical behavior of the conductive yarn. Experiments are conducted with actual embroidered contacts. The interpretation of results has been confirmed by a simplified contact model. A theory describing the contact mechanism in embroidered contacts has been developed