5 documents found, page 1 of 1
Small-size MEMS accelerometer encapsulated in vacuum using Sigma-Delta modulation
Lima, Vasco António Lourenço; Cabral, Jorge; Kuhlmann, Burkhard; Gaspar, Joao; Rocha, Luís Alexandre MachadoA vacuum encapsulated MEMS accelerometer using Sigma-Delta modulation is here presented. Three different modulation orders (second, third, and fourth) were implemented in a field-programable gate array (FPGA), enabling flexibility for tuning the loop parameters in real-time. Three devices were measured, and the results are in good agreement with simulations performed in Simulink. A noise figure of 123 μg/√Hz fo...
Fabrication of a MEMS micromirror based on bulk silicon micromachining combined...
Garcia, Ines S.; Ferreira, Carlos; Santos, Joana D.; Martins, Marcos Silva; Dias, Rosana Maria Alves; Aguiam, Diogo E.; Cabral, Jorge; Gaspar, JoaoA 1D MEMS (Micro-Electro-Mechanical Systems) mirror for LiDAR applications, based on vertically asymmetric comb-drive electrostatic actuators, is presented in this work employing a novel fabrication process. This novel micromachining process combines typical SOI-based bulk micromachining and grayscale lithography, enabling the fabrication of combs actuators with asymmetric heights using a single lithography ste...
Influence of mechanical stress in a packaged frequency-modulated MEMS accelerom...
Moreira, Eurico Esteves; Kuhlmann, Burkhard; Alves, Filipe Manuel Serra; Dias, Rosana Maria Alves; Cabral, Jorge; Gaspar, JoaoFrequency modulated accelerometers composed of two double-ended tuning fork (DETF) resonators on a differential configuration were characterized for their sensitivity to force applied to their package. Commonly, differential architectures are employed to cancel common mode errors, such as the mechanical stress or temperature dependency. The device dependence to mechanical stress was experimentally measured for ...
Highly-ordered silicon nanowire arrays for photoelectrochemical hydrogen evolut...
Thalluri, Sitaramanjaneya Mouli; Borme, Jerome; Xiong, Dehua; Xu, Junyuan; Li, Wei; Amorim, Isilda; Alpuim, P.; Gaspar, Joao; Fonseca, HelderVertically-aligned, highly-ordered silicon nanowire (SiNW) array photocathodes are fabricated employing e-beam lithography followed by deep reactive ion etching (DRIE) of Si. The effect of structural parameters of SiNWs, including wire diameter, length and inter-wire spacing, on their photoelectrocatalytic hydrogen evolution performance has been systematically investigated. Within the range of dimensions under ...
Amorphous oxygen-rich molybdenum oxysulfide Decorated p-type silicon microwire ...
Xiao-Qing Bao; Petrovykh, D. Y.; Alpuim, P.; Stroppa, Daniel G.; Guldris, Noelia; Fonseca, Helder; Costa, Margaret; Gaspar, Joao; Chuanhong JinWe report the fabrication of p-type silicon (Si) photocathodes consisting of well-ordered Si microwire (Si-MW) arrays coupled with non-precious and earth-abundant amorphous oxygen-rich molybdenum oxysulfide (MoOxSy) as both a hydrogen evolution catalyst and a passivation layer. The MoOxSyis conformally grown on the Si-MW surface through photo-assisted cyclic voltammetric (CV) deposition. By adjusting the cycle ...