Micro- and nanoelectromechanical (MEM/NEM) resonators are used in numerous fields of engineering and are crucial for time keeping, synchronization, and sensing applications. These systems are subjected to energy dissipation, which is a limiting factor in the performance. Extensive understanding is essential when nonlinearities show up in both stiffness and dissipation, to design appropriately. Focusing on dissipative mechanisms, this paper explores the vibrational behavior of a suspended clamped-clamped beam fabricated from silicon-nitride in the nonlinear regime. This study reveals a notorious decay in ringdown, when the resonator is decoupled from its vibrational power. A sustained amplitude is observed for up to 8 seconds. Though the exact source of this anomaly remains elusive, it is suggested that it might include modal coupling and/or optomechanical effects

Hermeticity is a measure of how well a package is leak-tight. Many Micro-Electro-Mechanical Systems (MEMS) sensors, actuators, and microelectronic devices need a defined cavity environment for optimal performance, hence measuring the package leak rate is critical for lifetime prediction. MEMS devices are generally packaged through the wafer-bonding technique. The MEMS device is produced on a wafer with a cavity and bonded to a cap wafer to seal the hole. Reducing the cap wafer thickness allows it to deflect due to the cavity interior-exterior pressure differential. Consequently, if leakage occurs, the deflection will
change. By measuring these deflections, it is possible to quantify leak rates.

In order to use it as an in-line testing process, this research aims to determine the accuracy of the deflection method for determining the leak rates. To achieve this, our approach involved designing and leak testing test structures (or devices) using an experimental setup that can vary pressure, supply desired species
inside a vacuum chamber, and measure deflection using an interferometer to determine leak rates. Deflections are converted to leak rates using a formulated analytical expression, subsequently utilized to determine the error involved in measuring leak rates.

Using the experimental setup, the test devices were effectively characterized for sensitivity using pressure-induced deflection measurements, with experimental sensitivity values closely matching the theory. Further, air leak testing was performed on devices interconnected with nanometer-gap size leak channels to
gain first-hand knowledge of leakage. Experimental leak rates matched well with analytical models, proving that flow through devices having leak channels can be characterized. Ultimately, the setup enabled successful helium leak testing of devices without any defined leak channels.

The helium leak-tested samples were circular membranes of diameters: 2000, 1600, 1400, 1300, and 1100 μm with a thickness of 40 μm bonded to a cavity depth of 3.24 μm. Uncertainty analysis associated with leak rate measurement revealed that when considering a certain cavity depth and membrane thickness,
the membrane with the largest diameter would exhibit the least amount of uncertainty. This was also observed through experiments, for the diameter of 2000 μm, a clear linear trend of deflection reduction due to the helium leakage was observed during a two-week period of deflection measurements. Whereas, for the diameter of 1100 μm, it was not possible to observe the same linear trend of deflection reduction, indicating that even more no.of.days is required to determine an accurate leak rate.

In the end, a short analysis was made using the cavity design having the 2000 μm membrane, which had the least uncertainty in measuring the leak rate. This analysis aimed to ascertain the designed test structure’s usefulness in measuring leak rates of the MEMS packages. Based on the analysis, it was concluded that large-volume wafer-bonded MEMS packages (> 1 mm3) with an acceptable cavity pressure increase of 10 mbar could be tested using the deflection method and our proposed test structure design to guarantee their lifetime.

Diamagnetic levitation presents a promising platform for realizing resonant sensors and energy harvesters. The technique offers mechanical isolation from the environment while operating with zero power consumption. This unique feature ensures exceptional sensitivity and accuracy in numerous applications. However, the presence of eddy currents in the levitating plate, induced by the alternating magnetic field, poses challenges, leading to increased damping and subsequently limiting the performance of levitating resonators. To address these issues, this study proposes a novel solution through the segmentation of diamagnetic plates. By dividing a pyrolytic graphite plate into smaller blocks, the flow of eddy currents is effectively restricted, resulting in reduced damping and significantly higher Q factors. By comparing the theoretical predictions using a FEM model from an earlier study with the measurements conducted the proposed technique is further validated. This comparative analysis demonstrates the effectiveness of the segmentation approach in mitigating damping due to eddy currents. Furthermore, the implementation of the proposed method led to remarkable results, with achieved Q factors exceeding 150 thousand.

In a world increasingly dominated by technological advancements, the demand for high-quality microphones has never been more present. Seamless speech recognition and the development of userfriendly hearing aids remain significant challenges. State-of-the-art micro-electromechanical system (MEMS) microphones are reaching their bottlenecks in terms of thermo-acoustic noise, caused by the acoustic resistance of the parallel plate capacitor. This constrains the achievable signal-to-noise ratio (SNR). This thesis presents a novel solution to address these challenges through the application of silicon photonics technology in the development of a silicon photonic microphone. Silicon photonics is a technology that uses silicon as an optical medium to create photonic systems with sub-micrometre precision, which can be used to create ultra-sensitive sensing devices. The optical sensors are fabricated on standard silicon-on-insulator (SOI) wafers, allowing for seamless integration with the precise and cost-effective complementary metal-oxide-semiconductor (CMOS) process. The optomechanical
sensitivity of the proposed microphone is derived for three different cladding materials that could be deposited on the wafer in the fabrication process. The thermal acoustic noise of the microphone is quantified. As the integrated photonic circuit does not require a backplate the design potentially reduces the thermal acoustic noise of current microphones by 44 %. The optimized design for the laboratory setup that is considered for this thesis can theoretically result in an SNR of 73.1 dB, which is roughly 5 dB more than the current state-of-the-art microphone technology.

Conventional Topology Optimization (TO) enables the inverse design of nanophotonic structures by specifying the objective and constraints without a predefined topological concept. Yet, extreme scenarios such as the design of a lightsail pose challenges that require new solutions. Here, a convolutional neural network (CNN) based TO methodology is extended to optimize a two-dimensional photonic crystal used to design a lightsail that aims to reach the nearest star (Alpha Centauri) within 20 years by achieving 20% of the speed of light. The CNN-TO performance is compared to a more conventional method of moving asymptotes (MMA) based TO by optimizing a photonic crystal unit-cell for the 2016 Starshot Initiative parameters. The CNN-TO requires up to 40% fewer iterations than MMA-TO to reach better performance under different operational conditions. The generated design turned out to be easy to fabricate, allowing them to be produced with optical lithography. Additionally, a study regarding the design challenges of the lightsail has been performed, which resulted in an optimization considering the functionality of the sail. Additionally, the study showed the sensitivity of the resulting design to varying objectives and materials. Therefore, underlining the necessity of considering multiple operating conditions (e.g. laser alignment and cooling) within the design process.

Optical microscopes are fundamentally limited to a resolution of several hundreds of nanometers by the diffraction of light. Single-molecule localization microscopy (SMLM) circumvents this limit by sparsely exciting fluorescent molecules at different time instances. Single molecules can subsequently be localized with improved precision over the diffraction limit. Due to their high frame rate, single-photon avalanche diode (SPAD) arrays are imagers that can be used for SMLM. Most SPADs have to recharge after each photon arrival. During this recharging period, the SPAD is insensitive to more photon arrivals. As a result, SPAD arrays will measure zero or one photons for each pixel in each frame, whereas scientific complementary metal-oxide semiconductor (sCMOS) imagers and electron multiplying charge-coupled devices (EMCCD) have a discrete frame output. Here, we describe the photon arrivals in the image formation model of the SPAD array as a binomial process rather than as a Poissonian process. In addition, we quantify the minimum theoretical uncertainty of single-molecule localizations using a binomial Cramér-Rao lower bound and benchmark it with simulated and experimental data. We show that if the expected photon count is larger than one for all pixels within one standard deviation of a Gaussian point spread function, the binomial CRLB gives a 46% higher theoretical uncertainty than the Poissonian CRLB. Without saturation, which is the case for most SMLM applications, the binomial CRLB model gives the same uncertainty as the Poissonian CRLB. Therefore, the binomial CRLB can be used to predict and benchmark localization uncertainty for SMLM with SPAD arrays for all practical emitter intensities.

A research gap exists in a targeted drug delivery into the brain with an implant placed on the outer surface of the cerebral cortex. If an implant with spatial control that can release drugs to a target location can be developed, it will provide efficient treatment opportunities for a variety of brain disorders such as strokes. One of the questions in realizing this implant is how to activate the drug release mechanism. Light is a promising activation stimulus due to its spatial precision and flexibility in the optical path. This thesis is a feasibility study into carrying light inside such a brain implant using a photonic crystal waveguide. Such a device must be soft and maintain its functionality during the mechanical bending imposed on the implant by the geometry and movement of the brain. A flexible 2D photonic crystal is simulated using COMSOL Multiphysics with the goal of designing a waveguide that functions with infrared light. The dispersion diagram of the photonic crystal is plotted to design for a bandgap at the operating wavelength. The transmission through a linear waveguide is calculated for the deformed state of the implant in mechanical bending, which is modeled as a 2D strain. A metallo-photonic crystal with photoresist nanopillars coated with a gold thin film and embedded in a flexible PDMS matrix is selected as the prototype for fabrication. The nanopillar arrays that form the photonic crystal waveguide are printed using two-photon polymerization (2PP), deposited with gold then transferred into photosensitive PDMS by drop casting. For characterization, a tapered rib waveguide is designed for light coupling and an optical end-fire test setup is built for transmission measurements on the fabricated device.

Vibration energy harvesters are especially interesting to use in an environment where there is one dominant vibration frequency present because then the harvesters can be designed to resonate at that specific frequency. To spread out the power yield over more frequencies a multi-modal harvester can be used which can resonate at multiple frequencies. A vibration with more than one sine wave can be manifested in a number of ways. The two frequencies can be present simultaneously, or they can alternate each other. How the energy harvesters react to these different vibration inputs is researched in this paper. Two fundamentally different multi-modal energy harvesters are used here. One which can be described by a coupled system of equations and one uncoupled. Two prototypes of an uncoupled and one coupled device are made and tested on an electromagnetic shaker. The vibration signals are sent to the shaker and the power output of the energy harvesters is measured using piezoelectric transducers mounted to the mechanisms. The results show that a phaseshift in the sine wave input signal generally results in a increase in power, where a decrease was assumed beforehand. When switching the input vibration from the first to the second eigenfrequency the power output does drop significantly, but the coupled mechanism has a substantially higher power output than the uncoupled device. And when the mechanisms are excited by a vibration with two eigenfrequencies at the same time no significant difference between the two can be observed, nor does the power output drop significantly. While the comparison between these two mechanisms is probably accurate, the quantitative conclusions must be taken with a grain of salt as it was noticed in a later stage of the research that the vibration signals were not consistent over the entire time period. At this point it is unclear if an overall better mechanism can be picked between the coupled and uncoupled one. However, it is shown that both have their distinct advantages where they outperform their counterpart, which can be used for designing a better energy harvester in future applications

The exceptional material properties of bulk diamond like high stiffness, high thermal conductivity, wide optical transparency, chemical inertness and bio-compatibility make it the material of choice in many high-end applications. Most present-day diamond micro-devices are fabricated by costly and time-consuming top-down methods, such as focussed ion beam milling or reactive ion etching. Hence, bottom-up methods that incorporate selective seeding and chemical vapour deposition (CVD) to produce micro-patterned poly-crystalline diamond are of interest. The present work introduces two novel methods for the bottom-up synthesis of nanocrystalline diamond micro-structures. The first method is based on the precise dispensing of nanodiamond dispersions from a hollow AFM cantilever and is used to manufacture freestanding diamond micro-resonators which are analysed on their frequency response. The second method incorporates maskless lithography to create stencils for selective seeding and enables patterned diamond growth on the single digit micrometer scale. A future step of growing such micro-structures in electrically conductive diamond could open up a vast new range up applications.

In pursuit of extremely sensitive sensors, the dimensions of these sensors get smaller and smaller. Small scale resonators are commonly used as sensors by relating changes in the dynamic behaviour to a sensed quantity. Conventionally, the dynamics used for sensing are in the linear regime. But at smaller scales the dynamic range of the linear regime decreases. Therefore, it is of interest to investigate the dynamic behaviour in the nonlinear regime, as with the decreasing scale of the resonators this becomes inevitable. Especially, little is known about the frequency stability in this region. The frequency stability is an indication for the potential sensitivity that the resonator can have as sensor. By using phase locked loop (PLL) the frequency stability around the resonance frequency of nonlinear resonators can be obtained. This research contains attempts to control multilayer graphene drums around its fundamental resonance frequency with PLL. In addition, the frequency stability at these points are presented by measure of the Allan deviation. There are roughly two different distributions of the frequency stability over the frequency response obtained. One resonator shows behaviour attributed to internal resonance. This internal resonance is linked to an increase of nonlinear damping. Combining that with a simple simulation model, a relation was found between increased nonlinear damping and an improvement of frequency stability.