[en] 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. (paper)

[en] Cell patterning commonly employs photolithographic methods for the micro fabrication of structures on silicon chips. These require expensive photo-mask development and complex photolithographic processing. Laser based patterning of cells has been studied in vitro and laser ablation of polymers is an active area of research promising high aspect ratios. This paper disseminates how 800 nm femtosecond infrared (IR) laser radiation can be successfully used to perform laser ablative micromachining of parylene-C on SiO₂ substrates for the patterning of human hNT astrocytes (derived from the human teratocarcinoma cell line (hNT)) whilst 248 nm nanosecond ultra-violet laser radiation produces photo-oxidization of the parylene-C and destroys cell patterning. In this work, we report the laser ablation methods used and the ablation characteristics of parylene-C for IR pulse fluences. Results follow that support the validity of using IR laser ablative micromachining for patterning human hNT astrocytes cells. We disseminate the variation in yield of patterned hNT astrocytes on parylene-C with laser pulse spacing, pulse number, pulse fluence and parylene-C strip width. The findings demonstrate how laser ablative micromachining of parylene-C on SiO₂ substrates can offer an accessible alternative for rapid prototyping, high yield cell patterning with broad application to multi-electrode arrays, cellular micro-arrays and microfluidics. (paper)