Wearable electronics applications have started to emerge in the consumer markets over the past few years, and the market forecasts look promising. Especially sports and healthcare industries have shown interest in the field, as wearables present possibilities of measuring one’s vital signals such as electrocardiography unobtrusively. To improve the unobtrusiveness of the wearable devices, stretchable electronics materials may be a more attractive choice than conventional rigid materials or even flexible materials. The ability of stretchable electronics substrates to adjust to the curvilinear surface of human skin lessens the user’s need to pay attention to the device.The objective of this thesis is to manufacture stretchable interconnects by screen-printing, and to characterize these interconnects. In this thesis, first the theoretical background is covered. Then the printing process is first evaluated by printing test patterns with different line widths, and the limits of the process are found in this manner. Next, special strain test patterns are printed and their initial electrical properties are measured. After this, the samples are stretched and the resistance is measured in real time. This way, the resistance’s proportionality of the strain is characterized for the interconnects. The mechanical properties such as the forces required for the strain and permanent deformations are also measured. Last, a small demonstration of a textile-integrated circuit implemented with stretchable materials is presented. It was discovered, that with the used materials and the used printing process, line width and gap width of 200 µm can be achieved with optimal printing parameters. However, with arbitrary patterns that have numerous different line widths, the optimizing might prove to be complicated. Hence, to have 95% throughput yield the minimum line width that can be used is 440 µm and the minimum gap width is 390 µm. The resulting sheet resistance for the manufactured strain test patterns had a mean value of 36.3 mΩ/□. However, the values had significant deviations, and the process should be optimized in the future. In the strain tests, half of the samples lose conductivity at approximately 74.1% strain. The normalized resistances of the samples rise linearly to approximately 30-40% strain, after which the growth rate starts to increase and is no longer linear. It was also discovered that no cracking can be found from the traces under 30% strains. In the mechanical tests, it was discovered that the force required to stretch these interconnects decreases after one strain cycle, and continues to slightly decrease on the following cycles. Due to this, the stretchable interconnects should be prestretched in the future in order to improve the unobtrusiveness of the application.
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