High-precision systems often comprise many individual systems, each operating at its own frequency. However, the vibrations from one system can be transmitted to another, which yields a response. In high-tech applications where precision is crucial, such as compliant transmission systems, these responses are undesired as they result in a loss in precision. Topology optimization can be employed to directly include these unwanted vibrations in the design process of compliant mechanisms. However, the current literature only concerns simple beam structures and suffers from issues such as premature convergence and large intermediate-density areas. This thesis aims to employ topology optimization to design compliant transmission systems whilst simultaneously attenuating the effects of unwanted external vibrations in the form of base excitations. This is done by using an objective function capable of minimizing the displacement response of a structure whilst not suffering from the aforementioned issues. The found objective function relies on the principle of global minimization, which minimizes the largest displacements inside the structure resulting from the applied excitation. An extension of the current research is done by only minimizing a subset of the domain, obtaining a localized minimization whilst other areas of the domain are allowed to exhibit larger responses. These two minimization principles are then applied to the design of a compliant inverter mechanism, with local minimization considering two areas of interest: the entire mechanism area and the regions around the input and output of the mechanism. The results show that global minimization is able to obtain discrete results for a large range of frequencies. Local minimization of the mechanism area yields lower displacement responses and, for higher frequencies, resulting topologies with displacement behaviour similar to the principles of vibration absorption and vibration isolation. Decreasing the response area to be minimized only to cover the input and output regions of the mechanism yields inconclusive results in terms of obtaining lower displacement responses compared to local minimization of the mechanism area. A proof of concept for designing a compliant transmission system whilst minimizing the response to harmonic base excitations is established, demonstrating potential benefits for future research in this domain.

The use of geometric anti-springs (GASs) in MEMS accelerometers can not only boost the sensitivity through the static balancing effect, it also introduces the capability to tune the stiffness post-manufacturing by adjusting the balancing force. This paper addresses the challenge of mechanically fine-tuning the stiffness to create the potential for compensating thermal drift of bias (TDB), whereas previous methods focused on doing so electrostatically. Due to the large effect of TDB on integration errors, creating this new method for compensation could help open up the way to more accurate inertial navigation by high-precision MEMS. As the basis of our research we used an existing accelerometer from Innoseis Sensor Technologies (version G6). Based on a theoretical analysis of the TDB, requirements were formulated and a design was developed through a combination of pseudo-rigid body and finite element modelling. By building a macro-scale prototype, we were able to validate our models. It can therefore be concluded that our design provides 8 additional compression steps ranging between 50 and 54 nm based on the model predictions. This proof-of-concept demonstrates to be a new tool in the design of future accelerometers with GASs.

Micromechanical resonators, which have become feasible due to advanced manufacturing techniques, have shown several interesting phenomena including mode coupling in a range of applications that span metrology and sensing. Conventional fabrication methods of these resonators have been used throughout the field. However, fabrication of micromechanical resonators by femtosecond laser ablation which could accelerate prototyping, access to three dimensional resonators and reduce clean room use, has received little attention.

In this study, a protocol for fabricating and measuring laser cut micromechanical resonators using computational analysis and experimental techniques has been developed and validated through comparison with previous works by characterising doubly clamped beam resonators. The fabricated prototype is demonstrated to exhibit autoparametric resonance and coupling showcasing the potential of the new approach in engineering and fast prototyping of coupled micromechanical resonators.

Compliant mechanisms are often used in precision mechanism design as a suspension for translational stages. Their light weight makes them efficient and they do not suffer from friction or backlash. They transmit and transform a finite motion along their degrees of freedom via elastic deformation and provide high stiffness along their degrees of constraint.
However, when they deflect the load bearing capacity in the degrees of constraint reduces considerably due to the risk of buckling induced by off-axis loading. Flexures are made thicker to prevail this phenomenon, but this also results in an increased actuation stiffness and ultimately a reduction in efficiency in their degrees of freedom. In this paper, a new concept is presented based on origami folding principles that exhibits a smaller decrease in support stiffness when it is deflected out of plane. On a conventional leaf flexure, a crease pattern is drawn based on compliant origami-inspired degree-4 joints. To make the origami-inspired leaf flexure out of metal lamina emergent mechanisms (LEM) are used for the crease lines. The prototype is analysed using a FE model which is validated by an experiment. Subsequently, a sensitivity analysis is performed on four characteristic design parameters. The results show that this new origami-inspired leaf flexure with $L = 65mm, w = 40 mm$ and $t = 0.30mm$ made of AISI 1.4301 stainless steel maintains 80.2 $\%$ of its initial support stiffness for a deflection of $y = 3mm$ compared to 36.9 $\%$ for a conventional leaf flexure with the same outside dimensions. However, the absolute support stiffness at $y = 3 mm$ of this new flexure was only 5 $\%$ of the leaf flexure for the same displacement. In conclusion, the decrease in support stiffness was reduced considerably, albeit at the expense of the actual magnitude of the support stiffness. For future studies more research is required on crease line design to improve the absolute values of the support stiffness.

Mode coupling has extensive use in the MEMS field, including frequency division, vibration direction conversion, and energy transfer. In practice, these applications can be used to improve the performance of various devices such as sensors and energy harvesters. Nonlinear spring also has a wide application in MEMS field. Various nonlinear spring mechanisms, such as fixed-angle bows, bistable rotational mechanisms, H-shaped springs, and topology-optimized planar springs, have been proposed and utilized. Nevertheless, there is a lack of non-electric design elements specifically designed for mode coupling. This thesis proposes a simple system demonstrating the feasibility of using a nonlinear spring to achieve mode coupling. The system incorporates a spring-mass system with two mass blocks, two linear stages, and a unique nonlinear spring compliant mechanism. The integrated components can be fabricated using 3D printing resin or high-precision femtosecond laser-cutting of silicon wafers. Additionally, a new crank-slider structure and a spline-shaped nonlinear spring are developed and studied for this system. Each has advantages and disadvantages, and is suitable for systems of different sizes and materials respectively. Their load-displacement relationship roughly satisfies the cubic relationship, but still has a linear term. The proposed system holds potential for enhancing the performance of sensors, energy harvesters, and other MEMS devices.

Origami-based mechanisms have emerged as a promising solution for developing locomotion systems. Its light-weight nature, scalability, and possibility for 2D monolithic manufacturing makes origami an attractive option for various applications, such as mobile robots and meta-surfaces. While various types of origami-based locomotion exist, constant-height walking locomotion does not have an origami-based solution yet. To achieve this, we present a 2-DOF crease pattern with two internal vertices and geometric constraints that can perform the required output path. A parametric study performed on the presented pattern reveals many different feasible geometries. Subsequently, these geometries are evaluated based on their capabilities to produce a path with minimized displacement along the Z-direction and minimal change in velocity of the end effector during propulsion. As a demonstration, we then utilized these results to optimize the design of a locomotion system for active surfaces. Finally, the results are verified with experiments using a physical prototype. In conclusion, the analysis of the results provides valuable insights in the behavior of the crease pattern, which can be utilized for designing and optimizing an origami-based locomotion system for other applications with different requirements.

The use of elastic frequency multipliers presents the ideal platform to address the coupling between the footprint and range of motion of elastic mechanisms. By transmitting unidirectional into reciprocating motion they efficiently increase the range of motion without a huge compromise in size. In this thesis, an elastic
frequency doubler based on an eight-bar mechanism that exploits the displacement around a singularity to double the frequency is presented. Higher frequency multiplications can be achieved by concatenating this mechanism, surpassing previous designs in the literature. To facilitate effective concatenation, criteria for optimization were established and a design study was conducted to determine the optimal geometrical parameters of the mechanism. The utilization of not only the actuation capabilities but simultaneously leveraging the inherently stored strain energy during operation has the potential to serve as the foundation for a novel group of architected materials. The embodiment of both functionalities makes these architected materials highly desirable for control in autonomous robots where, through the exploitation of close synergy and decrease in dissipation, this multifunctionality could increase the efficiency in usage of the usually limited space and available energy.

The use of origami-based mechanisms in the engineering field is growing as their advantages are better understood. Origami-based mechanisms have the advantage of being lightweight, compact, and their ability to transform from a flat sheet into complex three-dimensional structures makes them a source of inspiration to meet design challenges. A fold in paper is realized by a localized reduction in thickness, which reduces stiffness. Since most materials do not exhibit this property when folded, other techniques are used to facilitate this stiffness reduction. These include sandwiching a thinner material between rigid facets, or by thinning to create a groove joint (notch joint). The drawbacks of these techniques are that the first technique requires assembly, and the second technique requires complex material removal. Another technique has been proposed to reduce stiffness with simpler manufacturing methods, namely lamina emergent joints. These joints require cutting through the material, which can be done using well-established sheet manufacturing methods, such as laser cutting or stamping. However, the removal of material involves a trade-off between range of motion and stiffness in directions other than the desired bending motion. Initial research indicates that the groove joint is able to maintain the highest stiffness and range of motion, thus outperforming the lamina emergent joint. Therefore, the objective of this paper is to design an improved lamina emergent joint that approaches the performance of the groove joint. This is achieved by quantifying and evaluating the stiffness performance and range of motion of existing lamina emergent joints and then combining them on strong features. Improved designs are proposed that made an approach toward the groove joint and the best design was selected for optimization. The results showed that the selected design was not able to outperform the groove joint on both stiffness and range of motion. However, it was able to achieve similar in-plane shear stiffness and higher torsion stiffness than a groove joint with a lower thickness ratio. However, this also allowed more range of motion for the groove joint. So figuring out this trade-off between stiffness and range of motion is challenging and essential to design suitable joints in the future.

Mechanical computing systems have historically faced challenges in efficiently integrating computation and memory functions, often leading to complex designs and limited scalability in applications ranging from micro-electromechanical systems (MEMS) to programmable matter. This study aims to address this issue by introducing a mechanical system based on cellular automata (CA) principles, utilizing a bi-threshold tristable mechanism for implementing nonlinear Boolean functions. The system’s design translates Elementary Cellular Automata (ECA) rules, such as Rule 110, into mechanical motion using compliant multistable mechanisms. Finite Element Analysis (FEA) and pseudo-rigid body simulations validate the operational feasibility of this approach. The results confirm the system’s capability to process complex computational tasks by mechanically embodying specific ECA rules. This development marks a step forward in mechanical computing, offering a more integrated approach to computational material design. The research establishes a methodical design approach, enabling the embodiment of a wide range of Elementary Cellular Automata (ECA) rules within the mechanical framework. This approach extends beyond linearly separable Boolean functions, illustrating a significant advancement in mechanical computing capabilities. The findings provide a basis for future work in scaling the system and exploring its applicability in fields such as programmable matter and intelligent mechanical systems.

The range of motion of elastic energy sources is limited by the size of its transmission system. To enhance this range of motion without compromising the size, previous research introduced a frequency doubling mechanism with the intention to concatenate these mechanisms. This study serves to achieve higher numbers of frequency multiplication by concatenating up to three frequency doubling mechanisms. A crucial challenge is to reduce the input force required to operate the compliant design, even in the absence of output load, to ensure the output moves twice the distance of the input. The optimization process involved simulations to achieve a near-perfect Geometrical Advantage (G.A.) of 2 while ensuring the highest possible load capacity to minimize force-induced geometrical variations. The optimized mechanism was then statically balanced with buckled beams to minimize the input force of each frequency doubling mechanism. The buckled beams introduced negative stiffness, adding potential energy to counteract forces, and ultimately reducing the input force to approximately 5.3% of the initial force. Three frequency doubling mechanisms were concatenated and experimentally validated, achieving a frequency multiplication of 8. The real prototype demonstrated successful results, although the input force was not entirely eliminated, the desired frequency multiplication was achieved. These results form the basis for a compliant frequency multiplication mechanism, enhancing the range of motion of elastic strain energy sources through the implementation of a compact transmission system.

Mechanical metamaterials are architected materials with unique properties derived from their internal structure, rather than the material they consist of. Introducing distinct stable states into the material architecture allows the creation of mechanical metamaterials with multiple effective properties that can be altered post-fabrication. So far these so-called reprogrammable mechanical metamaterials have only demonstrated responsive behaviour, where the state of the metamaterial is dictated by the external input, leading to complex actuation and limited functionality. This research introduces a transformative approach to overcome these limitations through state-dependent switching, enabling metamaterials to autonomously determine their state based on internal information. Leveraging internal instabilities in the form of bistable and slender buckling elements, a contactless and tessellatable 3D unit cell design that can switch between positive and negative Poisson's ratios upon a specified displacement threshold is introduced. State transition occurs based on internal state information, rather than the external input, enabling adaptive behaviour. Both, Finite Element Analysis (FEA) simulations and experimental validation demonstrate the ability of the unit cell to switch between positive and negative Poisson's ratio under the same repeated input. Preliminary FEA simulations further suggest that through the tessellation of this innovative unit cell, the adaptive behaviour can be exploited to create mechanical metamaterials capable of adaptive shape morphing and repeatable counting abilities.

This thesis aims to solve the problems and fabricate fully inkjet-printed dielectric elastomer actuators with silver electrodes and a PDMS middle layer. First, a conductive silver electrode is printed on a coated PET substrate, followed by a printing of the dielectric elastomer middle layer to cover the bottom electrode. Then, the top silver layer is printed on the PDMS to achieve the top electrode. The problems intended to be solved in this work include printing the dielectric elastomer middle layer, treating
the PDMS layer, the significant surface cracking, and the non-conductivity of the top electrode. During the fabrication process, different concentrations of PDMS solution are tested printing. Observations on these printed samples are made to validate the most suitable printing solution and printing process/settings. Different surface treatment cycles for the PDMS layer are also adopted to determine the most suitable one, what effect is brought to the PDMS layer surface, and how they influence the top electrode. For the fabrication of the top electrodes, experiments are accomplished and repeated, coming with failures, which will be presented and discussed later. Lastly, displacement and frequency response measurements are essential to check the performance of the DEAs, being critical sections of the thesis.

Vibration energy harvesters have been proposed as a solution to increase the lifetime of wireless and portable medical devices. One example of implantable medical devices for which energy harvesters could be interesting, are pacemakers. With a lifespan of about 6 to 12 years, the battery must be replaced after this period of time. Using an energy harvester instead of a battery is therefore seen as an interesting alternative. However, the human heart rate is usually between 0.6-2Hz and consists of low acceleration peaks (<1g). The use of resonance at low frequency is extremely difficult, especially when the motion amplitude is larger than the device itself. A solution is sought in the non-resonant bistable energy harvesters. When enough force is applied to overcome the potential energy barrier, snap through motion is induced, resulting in a significant increase in power output. However, large threshold accelerations are limiting the usability of these systems. Therefore, stiffness compensation is required. A prototype was fabricated in which buckled flexures were used to add negative stiffness to a piezoelectric cantilever, resulting in a stiffness compensated bistable energy harvester suitable for energy harvesting from low frequency and low force excitations. The dynamical behaviour and practical performance of the prototype was studied in relation to a heartbeat, sawtooth wave and sine waves. The output power of the non-resonant prototype was compared to a resonant device, which in all cases showed that the non-resonant prototype outperformed the resonant device. This shows that stiffness compensated bistable energy harvesters can be used in order to make energy harvesting for low force and low frequency excitations, such as a heartbeat, possible.

In-situ sample holders with double-tilting capabilities are used to insert and position samples inside a transmission electron microscope for dynamic imaging. However, the performance of these sample holders, regarding energy-dispersive X-ray spectroscopy (EDS) analysis, is not on par with their single-tilt counterparts. By analyzing the EDS influences and the tilting mechanism of double-tilt sample holders, the need for a remote-center-of-motion (RCM) mechanism as a tilting mechanism is identified. Because existing RCM mechanism design strategies limit the design flexibility, a novel design strategy is developed. The novel strategy gives more flexibility in terms of the use of space, design for stiffness and it gives variable input/output link rotation ratio functionality. A compliant proof-of-principle mechanism, which is designed using the novel RCM mechanism design strategy, is manufactured to characterize the accuracy, force/displacement behavior and the input/output link rotation ratio. Analytical, numerical and experimental results are compared, and it can be concluded that the compliant RCM mechanism has potential to be used in double-tilt sample holders.

An Oldham coupling is a constant velocity rotational transmission between two misaligned but parallel axis. Conventionally, this coupling uses two sliding contact prismatic joints, in which friction, wear, backlash and lubrication is unavoidable. Conversion to a compliant mechanism, in which motion is accomplished by elastic deformation instead, would eliminate all these drawbacks. Within PME, such a coupling is designed already. However, it was observed that it does not perform well for higher velocities and accelerations. Furthermore, it was indicated that little research is available about the dynamic behaviour of compliant mechanisms at all.
In this thesis, the dynamic performance of the family of compliant Oldham couplings is analysed and predicted. A straightforward generic analysis method is proposed, based on multibody dynamics. A case study is performed on the existing compliant design to validate the proposed modelling techniques. Its dynamic performance is evaluated experimentally and its failure mechanisms are indicated. Based on the gained knowledge, design improvements are proposed. Finally, this work now facilitates the design and implementation of compliant Oldham couplings in dynamic applications.

Singularity points are causing problems in motion converters. A solution is found and experimentally validated.

At this moment there are more than 150 different designs of CMMA in existence. To aid the designer to develop a new or improved CMMA or choose what the design to use, a classification system is developed during the literature research. It is based on the geometrical advantage (GA) of the CMMA, and on the input and output port motion paths. Their properties resulted in 5 different classes, with a total of 50+ CMMA designs.
The mechanical efficientcy (ME) of CMMA or compliant mechanisms in general can be non- optimal because of the elastic energy storage during motion. A technique called static balancing, can be applied to improve the efficiency of the device.
A new way to apply the static balancing, without manual preloading, is developed for a straight-line micro mechanism. This technique allows applying static balancing on batch scale that was not available before. A MEMS design is developed and a prototype fabricated and tested. Another step closer in creating statically balanced for compliant mechanical micro motion amplifiers.

Vibration Energy Harvesting has the potential to become a convenient, sustainable and localized power source for the billions of small electronic devices of the future. One of the most challenging areas within this field is the design of miniaturized generators for power harvesting from human motion. In this thesis, a new strategy, design and prototype are presented for vibration energy harvesting from human motion.