Investigation of shock waves in explosive blasts using fibre optic pressure sensors

The published version of this article may be accessed at the link below. Copyright @ IOP Publishing, 2006.We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1 mm(2) in overall cross-section with rise times in the mu s regime and pressure ranges typically 900 kPa (9 bar). Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Results from blast tests are presented in which up to six sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.Support from the UK Engineering&Physical Sciences Research Council and Dstl Fort Halstead through the MoD Joint Grants Scheme are acknowledged. WN MacPherson is supported by an EPSRC Advanced Research Fellowship

A novel method for nanoprecision alignment in wafer bonding applications

Wafer bonding has been identified as a promising technique to enable fabrication of many advanced semiconductor devices such as three dimensional integrated circuits (3D IC) and micro/nano systems. However, with the device dimensions already in the nanometer range, the lack of approaches to achieve high precision bonding alignment has restricted many applications. With this increasing demand for wafer bonding applications, a novel mechanical passive alignment technique is described in this work aiming at nanoprecision alignment based on kinematic and elastic averaging effects. A number of cantilever supported pyramid and V-pit microstructures have been incorporated into the outer circumference area of the to-be-bonded Si chips, respectively. The engagement between the convex pyramids and concave V-pits and the compliance of the support cantilever flexures result in micromechanical passive alignment which is followed by direct bonding between the Si chips. The subsequent infrared (IR) and scanning electron microscopy (SEM) inspections repeatedly confirmed the achievement of the alignment accuracy of better than 200nm at the bonding interface with good bonding quality. The impact and potential applications of the developed alignment technique are also discussed