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

Fabrication and characterisation of suspended microstructures of tantalum

Funding: UK Engineering and Physical Sciences Research Council (EPSRC).An investigation of the influence of deposition and post-fabrication processes on the final mechanical structure of tantalum beams is reported in the present study. The final deflection profiles of doubly supported beams made from compressive and tensile-stressed films have been studied experimentally. An optimum finite element model has been developed to predict the buckling behaviour of the doubly supported beams by considering the boundary conditions in the form of a compressive stress and an applied load. No matter which etch release method has been used, the initial stress state of the as-deposited films has been found to have a significant impact on the final deflection profile of the fabricated device. The compressive-stressed films have presented larger deflection in the final released beams than the tensile-stressed films. Taking into account the type of etch release methods, the beams that have been released in the dry etch release processes have been found to deform more vertically than those released in the wet-etch release method. Moreover, it has been found that the amplitude of vertical deflection increases with the increase of the beam length and thickness. The results indicate that optimum profiles of tantalum suspended structures can be obtained from the tensile-stressed films that have been released by the wet etching method with an aspect ratio of 1:48.Publisher PDFPeer reviewe

Test structures for optimizing polymer electrolyte performance in a microfabricated electrochemical oxygen sensor

Test structures were produced for optimizing the design and fabrication of a patterned solid polymer electrolyte in an electrochemical oxygen sensor. Measurements showed that choice of photoresist developer and the underlying insulator material affected durability of the polymer structures. Test electrodes covered by the polymer were effective at supporting electrochemical oxygen detection

Pseudorandom Micromoulded Composites for High Resolution Ultrasound Imaging

No abstract available

Pseudorandom Micromoulded Composites for High Resolution Ultrasound Imaging

No abstract available

Micro-moulded randomised piezocomposites for high frequency ultrasound imaging

1-3 piezocomposites that can operate at over 30 MHz are in demand to improve spatial resolution on a sub-millimetre level for biomedical ultrasound imaging applications. However, the fabrication of such materials remains a challenge as ultrafine dimensions are required in conventional composite designs. We have previously reported the design of randomised composites to eliminate coupling to lateral modes and to relax overall dimensional constraints. In this work, practical fabrication of composites based on these designs has been realised by using a novel micro-moulding approach combining gel casting with soft lithography. Impedance spectra of randomised composites confirm their advantage for suppressing spurious modes. Pulse-echo responses of two completed transducers operating at 30 and 70 MHz have demonstrated their functional performance

Test structures for the characterisation of MEMS and CMOS integration technology

Test structures have been used to demonstrate the feasibility of bonding MEMS and CMOS wafers to create an integrated system. This involves using low temperature bonding along with CMP planarisation and wafer thinning. The last step in the integration process is bringing the electrical connections to the top surface and the creation of interconnect between the wafers. Test structures to evaluate this process have been designed and fabricated resulting in 7 - 9 Ω resistances for via chain structures. Via contact resistances of 6 × 10 -8Ω.cm 2 were measured using Kelvin test structures.</p