A pacemaker runs on a conventional battery that lasts for approximately 6-12 years, after which the pacemaker must be replaced. Converting the heart wall vibrations into electricity through a vibration energy harvester has been considered a promising solution to this problem. However, the complexity of the heart signals on which the energy harvester has to operate is a challenge. The human heart signal is a broadband signal, consisting of a varying acceleration amplitude at low frequencies. Most of the testing signals used in the labs are harmonic signals, Gaussian white noise or Gaussian coloured noise. These signals do not have the same characteristics as a human heart signal. In addition, the dynamical behaviour of an energy harvester differs per input signal. Therefore, it is important to test energy harvesters on the operation signal, in this case human heart acceleration signals. A heart signal differs per person depending on, for instance, someone's age, sex and health. This means that multiple human heart input signals are needed. Ethical requirements make the measurement of these signals with the necessary details a challenge in itself. In order to meet this demand and to avoid this ethical issue, a heart signal generator is developed as a first step towards the testing of energy harvesters on an approximation of human heart signals. Three different sources of heart signals are combined in order to obtain a new source of heart signals, an approximation of reality, which can be used for the testing. Speckle Tracking Echocardiography signals, open-chest pig heart acceleration signals and human chest motion acceleration signals are analysed and their characteristics are used as the source for the heart signal generator. This heart signal generator is able to mimic multiple heartbeats and the influence of the heart rate on the amplitude and signal duration. The disadvantages of accelerometer measurements are compensated with the advantages of Speckle Tracking Echocardiography measurements, and vice versa, in order to obtain an accurate and detailed heart signal. The output of the heart signal generator is a one-dimensional acceleration signal. An energy harvester is tested on multiple generated heart signals for a heart rate range of 120-200 bpm. It was observed that the mean power output and the efficiency of the energy harvester differs per heart signal. This shows that testing on multiple heart signals is crucial in order to validate that enough power is generated for charging the battery.

The Atalanta is a palm-sized, insect-inspired, flapping-wing micro air vehicle developed by the University of Technology Delft. In its current form, the Atalanta has a lift-to-mass ratio of 0.12 which inhibits it from taking off. Getting the Atalanta to fly would greatly benefit the research into areas such as aerodynamic modelling, on-board electronics, control and navigation and more. Designing and realizing a new, energy-efficient wing-system capable of producing 1.5 gram lift is found to be the most effective solution, with an expected lift-to-mass ratio of 0.85. Developing this new wing-system requires the design, manufacturing and integration of two parts: a wing and a compliant hinge. The wing is a wing-shaped, rigid plate that pushes air around to generate lift. The hinge is the interface between the Atalanta body and the wing, and allows the wing to passively rotate, i.e.: pitch, around its spanwise axis. For the fabrication of the wing, a hybrid structure is created by stacking sheets of different materials on top of each other, each with its own purpose. The sheets are laser cut before assembly to distributed material only where needed. The result is a wing consisting of a carbon frame for stiffness, a Mylar sheet for enclosing the wing surface area and a double-sided adhesive layer to bond the two together. For the compliant pitching hinge, a cross axis configuration of three leaf-flexures is selected. The combined pure bending motion of all three flexures allows the wing to rotate around its pitching axis. The flexures are fabricated and subsequently integrated into the wing structure, forming the new wing-system. The two main tests qualitatively asses the performance of the new wing-system. The first test measures the average stiffness of four hinges, and finds it to be a factor 27.8 higher than was expected. Measurement errors, incorrect input parameters, hinge flexure misalignment and corrugation at the edges of the flexures all can reduce the factor to 13.9, but the dominant reason is estimated to be curving of the flexures along their width. The second test determines the kinematic profile of the new wing-system; i.e. the sweeping and pitching angles during a single stroke. The results show that the wing-system operates at its resonance frequency of 8.5 Hz. This indicates that the energy efficiency of the new wing-system should be improved compared to the current wing-system. The 8.5 Hz sweeping frequency does mean a lower lift generation than expected, but this can be improved by reducing the mass of the wing and optimizing its topology. With some weight saving improvements the new wing-system should be more energy efficient while producing more lift compared to the current wing-system. The design and manufacturing processes are more flexible and consistent which makes experimental optimization of the mechanical properties of the wing-system easier. The novel cross axis hinge concept proves to be a valuable addition to the wing, although its fabrication can be improved upon.

There is a great amount of wave power in earth's oceans. The amount of power harvested for electricity is however very small in comparison to solar and wind. One of the reasons for this is the lack of consensus on the best design of wave energy converters. This thesis develops a novel system design for a wave energy converter array that has promise and implements, evaluates and compares control for it. The most important benefits of this new design versus the most used type of devices are that it does not rely on a connection to the ocean floor for energy harvesting and it is space efficient, meaning that devices lie close together. Control has never been designed for the type of device in this study to the best of this author's knowledge. The wave energy converter array consists of floating pontoons that are connected to each other. The wave energy is harvested through power take-off mechanisms in these connections. The most important requirement on the system design is survivability, as the ocean is a harsh environment. The kinematics are thus designed in such a way that forces on the connections can be set by the damping and stiffness coefficients of the connections. The array is optimized for efficient energy harvesting by its design, while keeping cost effectiveness in mind when possible. Not only the array itself is optimized for efficiency, the control is optimized for this as well. This means that the control problem is to maximize energy capture. Reactive and Resistive control are implemented and compared. A distributed version of these algorithms is investigated as well and improves on computation time for large arrays. Reactive control can improve upon Resistive control up to three times in terms of energy capture, depending on the efficiency of the power take-off mechanism. The reason for this great improvement is that Reactive control makes it possible for the array to reach resonance with the waves. The array performs average in terms of energy capture in comparison to other wave energy converters when Resistive control is used.

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.

Otosclerosis is a bone disease of the middle ear that often causes conductive hearing loss. This type of hearing loss can be treated by implanting a prosthesis, which replaces the stapes bone and attaches to the adjacent bone: the incus. Current stapes prostheses produce excellent hearing results, however the procedure is difficult to perform and success is not assured. With current prostheses, safe clamping forces cannot be accurately controlled, despite being crucial to the surgery’s long-term success. Inappropriate clamping force may cause slipping of the prosthesis or necrosis of the incus.
The objective of this study was to first create an overview of current prostheses and subsequently examine their pitfalls, and to design a new stapes prosthesis that addresses these pitfalls. Throughout the literature review a classification and evaluation system was developed to catalogue existing and future prostheses based on, for example, air bone gap difference, force controllability and ease of implantation. From this study we found the category of prostheses that utilise elastic material behaviour to securely clasp around the incus to have the most potential in a new prosthesis design.
Presented in this thesis is a novel prosthesis which features a bistable, fully compliant, two-dimensional mechanism, designed to be simpler to insert and with a more predictable clamping force compared with existing prostheses. For any incus diameter within the recorded range, the force around the incus is sure to be safe by design. The new prosthesis can be placed around the bone without causing unwanted stresses in the ossicles and joints, and is easily clicked shut.

Thermal oxidation in silicon microelectromechanical systems (MEMS) induces stress in the oxide film and silicon. Such residual stresses are usually unwanted, as it can influence performance or damage components. It can also cause unwanted plastic deformation in silicon, as was observed in previous research. Currentmeasurement methods inMEMSare not able to distinguish plastic and elastic strain as a result of thermal oxidation. This thesis presents a novel method to distinguish elastic and plastic strain in silicon beams, by removing the oxide layer to show the plastic strain. A lever mechanism is used as a mechanical amplifier. The plasticity model developed by Alexander and Haassen (AH) is
used in a numerical model to predict the elastic and plastic strain. Experiments in epitaxially grown silicon show significantly less plastic strain than predicted by the model. We conclude that the AH model is not valid for epitaxially grown silicon with low or zero initial dislocations. As significant plastic deformation was observed in FZ silicon samples in previous research by P.R. Kuppens, it is
concluded that epitaxially grown silicon is the better choice when plastic deformation is to be avoided.

The theories of energy harvester and complaint mechanism on micro scale have been developed vastly, however prototyping and realization of conceptual designs of such devices is difficult. Currently, micro scale prototyping devices can only be manufactured by means of lithography. However, lithography is expensive, both in terms of time and cost. Alternatively, laser micro machining is considered to be capable of precise manufacturing in micro scale, be able to bring down process time from months to a few days. Yet, thermal damage and mechanical performance of laser fabricated device have not been quantified and evaluated properly in literature, which are the challenge and goal of this thesis. The operation of laser system has been thoroughly studied , which enables replication of previous research in this area with a state-of-art quality.

Firstly, thermal damage was quantified by means of the piezoelectric property loss under high temperature. A set of taguchi process optimizations was conducted for optimal operational settings. Secondly, a micro double-flexure stage was manufactured by laser micromachining. Structural properties of the micro devices such as side wall surface roughness and beam geometry were measured, and stiffness in translational direction of the micro flexure structures were tested.

It is found that the piezoelectric property can be preserved by 99% by systematically optimizing the parameters. And it was found that stiffness of the laser micro machined silicon compliant mechanism is 16%-36% lower than lithography made ones due to thermal damage. Therefore a fast prototyping method for micro scale devices has been thoroughly studied and can be used for further researches and applications.

Current robots consume a lot of energy. The work required for a task is generally just a tiny fraction of the total energy consumed. Most energy wastefully dissipated. Design of the 2 degree of freedom (DoF) Plugless Robot Arm shows that clever design can reduce these energy losses to a tiny remaining fraction. The Plugless Arm is designed to perform a pick-and-place task displacing packages of 1 kg over a vertical distance of 1 m and some additional horizontal distance in a way that is capable of powering the full system.

Maximum energy recovery is achieved by the design of springs in parallel to the actuators such that minimal actuator currents lead to minimal electric heat losses. This requires simultaneous optimisation of the trajectory and the parallel elastic elements. In a Cartesian configuration a novel method is tested which allows for implicit optimisation of an elastic element without additional parameterisation. The optimal parallel spring characteristic can be expressed as a pure function of the trajectory if the system dynamics are defined as a function of position instead of time.

Afterwards the analytical optimal spring is replaced by a mechanism of low mechanical complexity showing similar energy characteristics. The mechanism is translated to a polar equivalent for the 2 DoF arm and optimised together with the trajectory of the arm. The optimal nominal trajectory is followed under undisturbed conditions when applying a pre-computed feedforward control signal to the actuators of the arm. Additional local optimal linear state feedback control is computed by means of Differential Dynamic Programming. All optimisation is done offline. Performance of the controller under disturbed conditions is tested in terms of accuracy as well as energy consumption.

The system achieves a nominal energy retrieval of 3.64 J per cycle of 2.5 s, which is sufficient to power a light controller, the necessary sensors and a special energy efficient gripper. Some energy is left which can be used by the controller to recover from disturbances which extract energy from the system. The controller is also able to recover additional energy from disturbances which add energy to the system.

The implementation of the controller is further optimised to achieve minimal computational energy consumption and memory requirements. By selective reduction of the control law, considerable data reduction is achieved with negligible impact on the controller performance.

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.