No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

We present the design and analysis of a new type of MEMS inertia switch with a tunable threshold, which can passively sense angular acceleration. The designs have a big proof mass for inducing rotation due to the angular impacts and also flexible cantilever beams to tune the acceleration threshold. The proposed designs were simulated using COMSOL Multiphysics, analytically modeled, and numerically integrated using MATLAB. The results showed that the acceleration can be tuned from 0 rad/s$^2$ to 65,000 rad/s$^2$ based on the used electrostatic voltage. The designs experience less than 10% overshot for shock durations higher than 20 ms. The rise time was less than 10 ms for all designs when the applied shock duration was less than 30 ms. The designs’ tunabilities were studied and characteristic angular acceleration versus tuning voltage graphs were developed for each design. The tuning voltage varied between the designs where the maximum pull-in voltage was 179 V in Design 2 and the minimum pull-in voltage was 59 V in Design 4.

Understanding electrically activated processes at electrode-electrolyte interfaces is needed to improve many technologies, including energy conversion, semiconductor devices, bio-sensors, corrosion protection, etc. In-situ spectro-electrochemical studies based on a wide range of spectroscopies are particularly useful. Scanning Transmission X-ray microscopy (STXM) is a synchrotron-based technique which measures near-edge X-ray absorption fine structure (NEXAFS) with high spatial resolution. In addition to information on morphology, STXM also provides chemical state analysis using the X-ray absorption data, which makes in-situ STXM studies of electrochemical process of special interest. This thesis reports ex-situ and in-situ STXM based qualitative and quantitative studies on copper (Cu) electrodeposition and electrostripping. The influence of electrolyte pH on the distribution of Cu(I) and Cu(0) species electrodeposited from aqueous CuSO4 solutions was studied. An instrument capable of performing in-situ flow electrochemical STXM studies was designed and fabricated. The performance of this device was evaluated for in-situ Cu electrodeposition studies. Findings based on ex-situ and in-situ STXM studies are discussed. Suggestions are made for further instrumentation improvements. / Thesis / Master of Science (MSc)

<p> Lithium niobate is an important photonic material that has potential applications in MEMS. Unfortunately, it is difficult to process using conventional methods. This thesis is an exploratory study to determine the viability of using a femtosecond laser as a fabrication tool for lithium niobate. Unexpectedly, a rich range of behaviour, likely arising from the complex material structure and composition, was discovered. Depending on the processing conditions, it was demonstrated that machining can either result in deep, high-aspect ratio grooves with minimal surrounding damage or dramatic modification of the lithium niobate to great depths with very little material removal.</p> <p> When machining grooves, increasing the effective number of pulses Neff (i.e. decreasing cutting speed) gave rapidly increasing ablation depths until a threshold was reached, after which the grooves were nearly filled with amorphous material. The depth of these amorphous channels rapidly saturates and becomes nearly independent of Neff. The ablation depth dependence on fluence showed gentle and strong ablation regimes. The amorphous channel depth depended almost linearly on fluence. Subsequent laser passes over amorphous channels eventually removed the amorphous material from the groove, indicating a dependence on the time between laser pulses. Crystal orientation was not a factor.</p> <p> The results are understood in terms of incubation and wave guiding. The first pulses ablate some material and incubate a channel of material below the surface. With further pulses, increasing incubation accelerates ablation. At the threshold Neff, the absorption coefficient has increased enough that the next pulse is able to melt a significant amount of material, which expands to fill the groove. It is suggested that, initially, the amorphous material is able to guide subsequent pulses to the bottom of the channel, resulting in a very slowly increasing depth with Neff. Subsequent passes cause ablation once again since compositional changes in the amorphous material have relaxed. Irradiated samples appear thermally reduced, which would create colour centres leading to increased absorption and thus incubation.</p> <p> Femtosecond lasers are indeed able to create MEMS structures. Multiple passes in the ablation regime yielded deep grooves, with laser polarization perpendicular to the groove giving the best results. Fabrication of micro-cantilevers and bridges was demonstrated.<p> / Thesis / Master of Applied Science (MASc)