ABSTRACT
There has been significant research focused on the development of stretchable materials that can provide a large area with minimal material usage for use in solar cells and displays. However, most materials exhibit perpendicular shrinkage when stretched, which is particularly problematic for polymer-based substrates commonly used in stretchable devices. To address this issue, biaxial strain-controlled substrates have been proposed as a solution to increase device efficiency and conserve material resources. In this study, we present the design and fabrication of a biaxial strain-controlled substrate with a re-entrant honeycomb structure and a negative Poisson's ratio. Using a precisely machined mold with a shape error of less than 0.15%, we successfully fabricated polydimethylsiloxane substrates with a 500 µm thick re-entrant honeycomb structure, resulting in a 19.1% reduction in perpendicular shrinkage. This improvement translates to a potential increase in device efficiency by 9.44% and an 8.60% reduction in material usage for substrate fabrication. We demonstrate that this design and manufacturing method can be applied to the fabrication of efficient stretchable devices, such as solar cells and displays.
ABSTRACT
Perimolysis is a type of intrinsic erosion--an irreversible dental demineralization linked to chronic regurgitation--which causes teeth to be more susceptible to dental caries. The purpose of this case report was to study a 35-month-old chronic vomiting child who visited the Department of Pediatric Dentistry in Yonsei Dental Hospital, Seoul, South Korea, for an evaluation of and treatment for the loss of tooth structure of his primary teeth. To prevent further destruction of the teeth and maintain occlusal height, all the posterior teeth were restored with stainless steel crowns and all the anterior teeth were restored with resin veneer crowns after pulpal treatment under general anesthesia. Therefore, when a child suffering from chronic vomiting visits a pediatric dental clinic, it is prudent to: (1) perform all possible dental treatment to control vomiting's adverse influences on the oral structures; and (2) refer the patient to a pediatrician to determine the cause of vomiting.
