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The aim of this work is to propose a mosquito-inspired (bioinspired) design of a surgical needle that can decrease the insertion force and the tissue deformation, which are the main causes of target inaccuracy during percutaneous procedures. The bioinspired needle was developed by mimicking the geometrical shapes of mosquito proboscis. Needle prototypes were manufactured and tested to determine optimized needle shapes and geometries. Needle insertion tests on a tissue-mimicking polyvinylchloride (PVC) gel were then performed to emulate the mosquito-proboscis stinging dynamics by applying vibration and insertion velocity during the insertion. An insertion test setup equipped with a sensing system was constructed to measure the insertion force and to assess the deformation of the tissue. It was discovered that using the proposed bioinspired design, the needle insertion force was decreased by 60% and the tissue deformation was reduced by 48%. This finding is significant for improving needle-based medical procedures. [ABSTRACT FROM AUTHOR]

The ultimate goal of our research is to develop a wireless, remotely activated, and implantable bone transport (lengthening) device. Our device is subcutaneously mounted on the periosteal surface of the tibia. Smart materials such as temperature-driven nitinol and magnetostrictive terfenol-D were investigated to be used as actuators to provide the required forces for the bone transport process. It was found that an actuator based on terfenol-D with a magnetic field applied transversely (along the material's magnetic moment) was the more appropriate technology. Design concepts and proof-of-concept work of both smart material technologies are presented. [DOI: 10.1115/1.3160314] Keywords: nitinol, terfenol-D, smart magnetostrictive material, smart actuators

Printed circuit boards (PCB's) often warp when subjected to temperature changes, associated with either the manufacturing process or the usage. In order to reduce the warpage, waviness was introduced in the electric traces. Model PCB's were manufactured and tested. The elastic stiffnesses of the PCB's were determined using a coupled experimental-analytical vibration method, whereas coefficient of thermal expansions (CTE's) and warpage were measured by placing strain-gage instrumented specimens in an environmental chamber and varying the temperature. Unit cell finite element (FE) analyses of PCB's with both straight and wavy traces were performed to predict thermoelastic behavior. Both experimental tests and numerical analyses conclude that the PCB's with wavy traces warped approximately 40% to 60% less than the PCB's with straight traces.

The electric copper lines in printed circuit boards (PCBs) introduce anisotropy in the various layers in multilayered PCBs. This anisotropy in combination with a general lack of symmetry with respect to the PCB midplane is a cause for thermally induced warpage. An analytical model which can predict the thermomechanical properties and warpage of PCBs with various electric artworks was developed. The model is based on Kirchhoff plate theory. An effective medium assumption was employed for the layers consisting of copper lines and composite side by side. The properties of the effective medium were obtained by a combination of Voigt (constant strain) and Reuss (constant stress) predictions, in conjunction with three-dimensional finite element unit cell calculations to determine a few constants. The prediction of the model conform well to some recent experiments. The model was finally used to "tune" the electric artwork of a PCB to minimize thermally induce warpage by changing trace widths and spacings in a six layered board. The calculations predict that isothermal warpage could be reduced by more than 90% for this board. [ABSTRACT FROM AUTHOR]