A fully mechanical microsystem for detecting multiple acceleration threshold violations is presented. It combines a seismic mass as a part of a ratcheting mechanism so that discrete positions are enabled depending on the external acceleration forces.A numerical model describing the dynamic system behavior has been developed. The fabricated system demonstrator is investigated utilizing impact tests, and the numerical model is verified by comparing the model with the measurement values. Various acceleration thresholds between 5g and 30g could safely be measured. Additionally, the counter can be re-initialized utilizing an electrostatic actuator for releasing the ratcheting mechanism.This recording of acceleration events does not require electrical energy for detection nor for storage; hence it is suitable for monitoring of sparse but critical acceleration or impact events over large time periods. The system design is prepared for an electrical read-out by, e.g. RFID transponders or comparable systems that transmit the position of the seismic mass within the ratcheting mechanism. (C) 2015 Elsevier B.V. All rights reserved.

The development of micromechanical energy harvesters establishes innovative supply options for self-powered nodes of multimodal sensor networks. In this work a novel electrostatic realization as vertical overlap type is demonstrated by design concept, topologies and microfabrication of single-layered test structures. This approach provides high areal densities of capacitance (Cmax in three-digit pF range for chip area =15x15 mm(exp 2)), vertical deflections up to 100 micrometer and high capacitance ratios Cmax/Cmin for an enhanced output power. Technological main points are the deep reactive etching of comb electrodes with high aspect ratio (clearance =3 micrometer for depth =100 micrometer) and the manufacturing of a highly z-compliant spring guidance with acceptable transverse stiffness. In dynamic characterization first vibrometric measurements on released test structures prove their ability to oscillate, showing deflection amplitudes in the higher twodigit micrometer range. Considering design-related parasitics, quasistatic capacitance measurements show capacitance ratios up to Cmax/Cmin=3.8. The further realization of multilayered comb-drive structures with vertically isolated stator planes will lead to higher power densities for the intended mediate but continuous extraction of small amounts of electrical energy from ambient, low-frequent vibrations.

In medicine early diagnostics are important for the healing process of the patient. Intelligent implants allow a better determination of vital parameters and can offer an optimal medical care during the therapy. But for such devices the power supply is a challenge. The need of space for batteries and other solutions where energy is transmitted wirelessly is too big for miniaturized applications in the eye. A practical alternative for this could be energy harvesting by using eye movement. For dimensioning the parameters of the harvester, the characteristics of eye movement were investigated. These datasets give a first overview of the mechanical potential to harvest energy for an intelligent implant.

In this work we report on non-resonant piezoelectric micro-energy-harvesters based on corrugated membranes made from aluminium nitride. These harvesters were designed to respond efficiently to aperiodic mechanical impact at low repetition rates. The piezogeneration efficiency of non-resonant systems was compared to conventional resonant devices like tensile stressed membranes and cantilevers. Special attention was paid to system properties that allow an operation at low frequencies in viscous media with high damping. Classical analytical modelling was employed to describe the corrugated microsystems with the aim to calculate the feasible energy outcome and to optimise electro-mechanical coupling.

Arrays of two-degree of freedom analog micromirrors are designed for use within an high-contrast projector and fabricated using a multi-user MEMS fabrication process. We demonstrate a novel way of optimizing the tradeoffs between tilt angle and mirror size by subdividing the mirrors into smaller functional subsections that move synchronously. The mirror design employs multiple mirrors within a gimbal frame. The frame rotates around one axis, and each mirror within the frame rotates around a perpendicular axis, resulting in two-degree of freedom rotation. The design employs specific electrode shapes to allow one-layer connections. Using these fabricated mirrors, simultaneous actuation of mirrors within a composite structure is achieved. A prototype array of fabricated mirrors is described, with 6×5 mirrors each of 160μm×160μm forming one composite mirror of an array, giving total active area of 960μm×800μm. The mirrors can achieve a maximum tilt angle of 2.25°. The fill factor of this design is 68%.

This work aims for utilizing human ocular motion for the self-sufficient power supply of a minimally invasive implantable monitoring system for intraocular pressure (IOP). With a proven piezoelectric functionality (d33>5 pm/V), nanocrystalline thin films of aluminum nitride (AlN) provide a good capability for micromechanical energy harvesting (EH) in medical applications. Many d31-mode microcantilever architectures are poorly suited for human-induced EH: Resonant mass-spring-damper systems are tested under high, narrow-band excitation frequencies. However, human motions, e.g. vibrations of eyeballs are marked by their low frequency, unpredictable, mainly aperiodic and time-varying signature. Different vibration types and directions are 3-dimensionally superimposed. Saccadic eye movements are favorable for inertial microgenerators because of their high dynamic loading (ω≤1000°/s). Our generator concept (symmetric active/active-parallel-bimorph cantilever) enables a high structural compliance by maximizing the piezoactive volume at very low cantilever thicknesses (<1 μm). An increased length and seismic mass enable an effective excitation by low-level aperiodic vibrations such as saccadic acceleration impulses. Analytic calculations and FEA-simulations investigate the potential distribution and transient response of different bimorph structures (length 200- 1000 μm, width 20-200 μm) on broadband vibrations. First released monomorph and bimorph structures show very low resonant frequencies and an adequate robustness.

Fur die Sensorik eroffnet der Einsatz von nanostrukturierten Materialien, die mit begrenztem Aufwand umsetzbar sind und fur die keine kostspieligen und sehr aufwendigen Technologien benotigt werden, neue Perspektiven. Die Mikro-Nano-Integration, also die Integration von Nanostrukturen in Mikrosysteme, ist zumindest ein hochst interessantes Thema fur zukunftige Sensoren. Vorgestellt werden hier beispielhaft nanostrukturiertes Siliciumgras, das durch Selbstmaskierung in Trockenatzprozessen erzeugt werden kann, und nanokristallines Aluminiumnitrid, das mittels reaktiver Sputtertechnik erzeugt wird. Wahrend Siliciumgras insbesondere fur extrem grose Oberflachen sorgt und auch als infrarot-optisches Interface von Bedeutung ist, sind Membranen aus nanokristallinem Aluminiumnitrid, das auch piezoelektrische Eigenschaften aufweist, extrem stabil und weisen eine sehr hohe thermische Leitfahigkeit auf.