Bio-based soft elastomeric capacitor for structural health monitoring applications

Large-area electronics are typically fabricated from petroleum-based polymers. However, petroleum has negative impacts on the environment and is expected to last for only another 80 years. Much attention, as a result, has been brought to minimize the usage of petroleum-based products and move towards environmental friendly products. This thesis presents a bio-based soft elastic capacitor (SEC), which is flexible and mainly made of water and vegetable oil. The SEC is composed of dielectric sandwiched between two electrode layers and it is used in structural health monitoring applications. The linearity of the sensor and its ability to transduce local strain of large surfaces into change in capacitance is demonstrated in this work. Additionally, the materials properties was tested and good physical and chemical properties are shown despite a decay of the dielectric that occurs after the first 16 days of fabrication

Bio-Based Soft Elastomeric Capacitor for Structural Health Monitoring Applications

Recent advances in flexible electronics have enabled the development of large-area electronics, which are typically fabricated from petroleum-based polymers. With the rapidly growing market of flexible electronics and sensors, there is a pressure to move toward environmentally friendly products. In this article, a bio-based polyurethane soft elastomeric capacitor for structural health monitoring applications is presented. The sensor’s dielectric is fabricated using castor oil–based waterborne polyurethane, mixed with titanium dioxide, which replaces petroleum-based dielectric materials (e.g. styrene-ethylene/butylene-styrene) previously used by the authors. A critical advantage of the proposed castor oil–based polyurethane over styrene-ethylene/butylene-styrene is the environmentally friendly nature of the bio-based polymer and water-based fabrication process of the dielectric that limits the use of solvents. Static characterization demonstrates the linearity of the sensor and its ability to transduce local strain of large surfaces into change in capacitance. Material test results show good physical and chemical properties, despite a decay of the dielectric that occurs after the first 16 days of fabrication

Bio-based soft elastomeric capacitor for structural health monitoring applications

Large-area electronics are typically fabricated from petroleum-based polymers. However, petroleum has negative impacts on the environment and is expected to last for only another 80 years. Much attention, as a result, has been brought to minimize the usage of petroleum-based products and move towards environmental friendly products. This thesis presents a bio-based soft elastic capacitor (SEC), which is flexible and mainly made of water and vegetable oil. The SEC is composed of dielectric sandwiched between two electrode layers and it is used in structural health monitoring applications. The linearity of the sensor and its ability to transduce local strain of large surfaces into change in capacitance is demonstrated in this work. Additionally, the materials properties was tested and good physical and chemical properties are shown despite a decay of the dielectric that occurs after the first 16 days of fabrication.</p

Bio-Based Soft Elastomeric Capacitor for Structural Health Monitoring Applications

Recent advances in flexible electronics have enabled the development of large-area electronics, which are typically fabricated from petroleum-based polymers. With the rapidly growing market of flexible electronics and sensors, there is a pressure to move toward environmentally friendly products. In this article, a bio-based polyurethane soft elastomeric capacitor for structural health monitoring applications is presented. The sensor’s dielectric is fabricated using castor oil–based waterborne polyurethane, mixed with titanium dioxide, which replaces petroleum-based dielectric materials (e.g. styrene-ethylene/butylene-styrene) previously used by the authors. A critical advantage of the proposed castor oil–based polyurethane over styrene-ethylene/butylene-styrene is the environmentally friendly nature of the bio-based polymer and water-based fabrication process of the dielectric that limits the use of solvents. Static characterization demonstrates the linearity of the sensor and its ability to transduce local strain of large surfaces into change in capacitance. Material test results show good physical and chemical properties, despite a decay of the dielectric that occurs after the first 16 days of fabrication.This is a manuscript of an article from Structural Health Monitoring, 14(2), 2015: 137-147 doi:10.1177/1475921714560072.. Posted with permission</p

Smart sensing skin for detection and localization of fatigue cracks

Fatigue cracks on steel components may have strong consequences on the structure's serviceability and strength. Their detection and localization is a difficult task. Existing technologies enabling structural health monitoring have a complex link signal-to-damage or have economic barriers impeding large-scale deployment. A solution is to develop sensing methods that are inexpensive, scalable, with signals that can directly relate to damage. The authors have recently proposed a smart sensing skin for structural health monitoring applications to mesosystems. The sensor is a thin film soft elastomeric capacitor (SEC) that transduces strain into a measurable change in capacitance. Arranged in a network configuration, the SEC would have the capacity to detect and localize damage by detecting local deformation over a global surface, analogous to biological skin. In this paper, the performance of the SEC at detecting and localizing fatigue cracks in steel structures is investigated. Fatigue cracks are induced in steel specimens equipped with SECs, and data measured continuously. Test results show that the fatigue crack can be detected at an early stage. The smallest detectable crack length and width are 27.2 and 0.254 mm, respectively, and the average detectable crack length and width are 29.8 and 0.432 mm, respectively. Results also show that, when used in a network configuration, only the sensor located over the formed fatigue crack detect the damage, thus validating the capacity of the SEC at damage localization.This is a manuscript of an article from Smart Materials and Structures; 24(6)2015;1-16. Doi: 10.1088/0964-1726/24/6/065004. Posted with permission.</p