1,830 research outputs found
A traction-free model for the tensile stiffness and bending stiffness of laminated ribbons of flexible electronics
No full textLaminated ribbons have been widely adopted for structures of flexible electronics to simultaneously achieve the electronic functions and mechanical performances. Their effective tensile stiffness and bending stiffness, which are extensively used as fundamental parameters
in the mechanical analysis, are usually obtained by the plane-strain hypothesis for simplicity. However, it is found that the practical condition is usually closer to the traction free, even for the cases with a relatively large width. Here, a traction-free model is proposed to analytically obtain the effective tensile stiffness and bending stiffness of laminated ribbons,
which can be used directly in the mechanical analysis of flexible electronics. The prediction of the traction-free model agrees very well with the precise result obtained by 3D finite element analysis (FEA) for the cases that are in the range of structure designs of flexible electronics. It is found that the tensile/bending stiffness of traction-free model is between the plane-stress model and plane-strain model, but is closer to the plane-stress model. The use of the plane-strain model sometimes may yield a considerable error in the mechanical analysis of flexible electronics. The parameter study shows that this model is very important for the problems with advanced materials, such as metamaterials with negative Poisson’s ratio. This work provides a theoretical basis for the mechanical analysis of flexible electronics.</p
Stretchable Strain Sensors Based on Deterministic-Contact-Resistance Braided Structures with High Performance and Capability of Continuous Production
No full textOwing to their potential applicability in wearable devices and intelligent robots, stretchable strain sensors have been widely investigated. However, fabricating sensors with high sensitivity, wide sensing range, high repeatability, robustness, and capability for continuous production remains challenging. Herein, a deterministic-contact-resistance braided structure (DCRBS)-based stretchable strain sensor is proposed. The polyester yarns in the sensor tightly trap the silver fibers with the latex thread substrate to form a periodic Y structure to avoid slippage of the fibers, thereby facilitating deterministic contact and separation between the silver fibers during cyclic stretching. Owing to this braided structure, the strain sensor exhibits high repeatability (repeatability error = 3.74%), high sensitivity (gauge factor up to 140), wide sensing range (50%), and high robustness (washability, insensitivity to micro-defects). Additionally, the strain sensor can be continuously mass produced using mature raw materials and processing technology. Because of its demonstrated excellent performance, the strain sensor can find applications in human motion monitoring, rehabilitation medicine, and robotic control.</p
Sojourner, April 1992
No full textProducers: Su-Yin Lee, Elspeth Slayter, and Pat Thompson.University YW. (1992). Sojourner, April 1992. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/275182
Sojourner, October 1992
No full textProducers and Editors: Su-Yin Lee, Elspeth Slayter, and Pat Thompson.University YW. (1992). Sojourner, October 1992. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/275178
Association of cutaneous necrotizing eosinophilic vasculitis and deep vein thrombosis in hypereosinophilic syndrome
No full textScaling Effects in the Mechanical System of the Flexible Epidermal Electronics and the Human Skin
No full textThe "island-bridge" mesh structure is widely adopted for flexible epidermal electronics to simultaneously achieve the electronic functions and mechanical flexibility. Mechanical intuition tells that the small size of the "island" is beneficial to the flexibility of the structure and the adaptability to complex geometric targets. Here, a plane-strain model and an axisymmetric model are established for square "island" and cycle "island," respectively, to analyze the mechanical system consisting of the flexible epidermal electronics and the human skin. It is found that the pressure between the "island" and the human skin is positive at the inner region and reaches a peak value at the center, while is negative at the outer region and approaches infinite at the boundary of the contact region. With the increase in the size a/R-0, the amplitude of the pressure significantly increases, as well as the singular degree of the pressure at the boundary. The reduction of the "island" size is beneficial for the optimization of the "comfort level" of the flexible epidermal electronics. The models degenerate into the famous Johnson-Kendall-Roberts (JKR) model for the limit case with extremely hard and thick "island."</p
Magnetic resonance cholangiography for evaluation of cholestatic jaundice in neonates and infants.
No full textAdhesion-Free Thin-Film-Like Curvature Sensors Integrated on Flexible and Wearable Electronics for Monitoring Bending of Joints and Various Body Gestures
No full textFlexible and wearable electronics integrated with various sensors have great potential for applications in monitoring human activities and personal health. Bending and tension/compression dominate the deformation modes yielded by flexure of joints and diverse body gestures. A key challenge now is to sense the curvature/bending angle, while much research has been focused on the strain sensors for tension/compression. Alternative approaches by strain sensors or noncontact optical methods for curvature sensing are not practical for wearable electronics. A novel adhesion-free thin-film-like curvature sensor that can monitor bending activities is introduced for flexible and wearable electronics. This study presents comprehensive design, fabrication, mechanism, structural analysis, performance characterization, and device-level demonstrations for bending of joints, gesture recognition, and real-time sitting posture correction. The most prominent advantage of the present sensor is that the measurement is independent of the strain of the target surface and the interfacial slippage, thus the perfect adhesion between the sensor and the surface is unnecessary. The features of adhesion-free, simple mechanical principle, low cost, and satisfactory monitoring results highlight the superiority of the present curvature sensors for practical applications to flexible and wearable electronics.</p
Direct numerical simulation of turbulent Couette-Poiseuille flow with zero skin friction
No full textThe near-wall scaling of mean velocity U(y) is addressed for the case of zero skin friction on one wall of a fully turbulent channel flow. The present DNS results can be added to the evidence in support of the conjecture that U is proportional to √yw in the region just above the wall at which the mean shear dU/dy = 0
- …
