HSG IMIT Institute of Micromachining and Information Technology

Villingen-Schwenningen, Germany

HSG IMIT Institute of Micromachining and Information Technology

Villingen-Schwenningen, Germany

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Hoffmann D.,HSG IMIT Institute of Micromachining and Information Technology | Folkmer B.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,Albert Ludwigs University of Freiburg
Journal of Micromechanics and Microengineering | Year: 2011

This paper investigates triangular electrode structures for electrostatic energy-harvesting devices. By analysis of the electrode geometry, we identified the angle α, which is half the angle defined by the two equal sides of the isosceles triangle, to be an important design parameter. Moreover, triangular electrodes provide a larger capacitance change per unit displacement and also a larger total capacitance change than area-overlap and gap-closing designs. Fabricated devices were characterized using two different circuit configurations. Our results show a nonlinear frequency response (softening behaviour) due to the nonlinear capacitance characteristic of the triangular electrodes. However, the nonlinear capacitance characteristic allows tuning the resonance frequency of the device. We also observed that a bias voltage as low as 8 V allows effective operation of the energy-harvesting device. Finally, we demonstrate successful charging of a 20 νF energy storage capacitor to a practical voltage level of 3.5 V. The harvested energy was applied to a low power transmission module which successfully transmitted a data communication protocol. © 2011 IOP Publishing Ltd.


Schopp P.,Albert Ludwigs University of Freiburg | Klingbeil L.,HSG IMIT Institute of Micromachining and Information Technology | Peters C.,Albert Ludwigs University of Freiburg | Manoli Y.,Albert Ludwigs University of Freiburg | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology
Sensors and Actuators, A: Physical | Year: 2010

This work reports on a gyroscope-free inertial measurement unit (GF-IMU) that only comprises linear accelerometers in order to directly measure the transversal acceleration as well as the angular acceleration and velocity. The accuracy of the calculated body motion depends on the geometrical setup and the variance of the employed accelerometers. Therefore, an analytical evaluation of the sensor placement for the propagation of the sensor variance is provided here. The positions and orientations of the sensors within the body frame have to be known precisely in order to calculate the exact inertial movement of the body. With the calibration scheme presented here it is possible to identify these parameters completely even without any previous knowledge. Furthermore, the variance of the parameters can be determined, which can be used to evaluate the performance of the calibration. Using only acceleration sensors it is not possible to determine the direction of a rotation. To overcome this drawback, an Unscented Kalman filter (UKF) is applied to merge the information of the angular acceleration and the angular rate and thus robustly estimate the sign of the angular velocity. Measurements on a 3D-rotation table were carried out to exemplarily demonstrate the accuracy improvements after the calibration. Thereby, the RMS error of the angular rate was reduced by a factor of 2.8. © 2010 Elsevier B.V. All rights reserved.


Leicht J.,Albert Ludwigs University of Freiburg | Maurath D.,Albert Ludwigs University of Freiburg | Manoli Y.,Albert Ludwigs University of Freiburg | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology
European Solid-State Circuits Conference | Year: 2012

This paper presents an efficient autonomous micro energy harvesting interface optimized for high-resistive vibration-driven electromagnetic energy transducers. A novel active voltage doubler and an energy processing scheme with adaptive maximum power point tracking (MPPT) is implemented. The interface enables wide voltage range harvesting for amplitudes between 0.44 V and 4.15V. Harvesting with tracking efficiencies of up to 93% and total efficiencies of up to 72% is enabled. In order to supply energy harvesting applications such as low power wireless sensor nodes a programmable voltage stabilization is implemented. The prototype chip is fabricated in a 0.35 μm CMOS process and is self-supplied needing no start-up help. © 2012 IEEE.


Hoffmann D.,HSG IMIT Institute of Micromachining and Information Technology | Folkmer B.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,Albert Ludwigs University of Freiburg
Journal of Physics: Conference Series | Year: 2014

In this paper we present experimental results from an energy harvesting system with two coupled energy harvesters. The energy conversion mechanism of the two coupled energy harvesters is based on the electromagnetic principle. The coupling is generated by two magnets in a repulsive arrangement. In this manner a bistable configuration can be obtained if the gap between the magnets is sufficiently small. We demonstrate that the total power output can be increased in comparison to a linear reference system, if specific conditions are fulfilled. In this respect, the highest power output occurs in the nonlinear region of a monostable system configuration, mostly near the transition to a bistable configuration. On the other hand, the results also indicate, that a bistable operating mode does not necessarily enhance the power output of the coupled system. © Published under licence by IOP Publishing Ltd.


Northemann T.,Albert Ludwigs University of Freiburg | Maurer M.,Albert Ludwigs University of Freiburg | Rombach S.,Albert Ludwigs University of Freiburg | Buhmann A.,Albert Ludwigs University of Freiburg | And 2 more authors.
Sensors and Actuators, A: Physical | Year: 2010

This paper demonstrates a micro-electro-mechanical gyroscope system with extensive use of sigma-delta (ΣΔ) modulation in both, primary and secondary modes. Both control schemes are implemented digitally on a field programmable gate array (FPGA). The primary loop has a bandpass ΣΔ digital-to-analog converter (DAC) driving the primary mass into resonance using a two-level driver. With this strategy of replacing the discrete DAC of the primary oscillation control with a bandpass ΣΔ-DAC, the analog circuit complexity is enormously reduced. The Coriolis rate signal is converted into a bit stream with a new excess loop delay (ELD) compensated micro-electro-mechanical ΣΔ modulator (ΣΔM) incorporating the gyroscope in the loop with a second-order electrical bandpass filter (BPF). To investigate the ELD effect, this electro-mechanical ΣΔM is implemented on the FPGA emulating continuous-time (CT) behavior. Measurements show stable modulators, with an ELD of nearly one clock period of the sampled system, achieving in-band noise (IBN) below -60 dBFS. The full-scale (FS) is measured to 1019°/s. This paper demonstrates that the stability of ΣΔ modulators with large ELD can be ensured with the new ELD compensation technique. © 2010 Elsevier B.V. All rights reserved.


Mohamed S.A.S.,Albert Ludwigs University of Freiburg | Manoli Y.,Albert Ludwigs University of Freiburg | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

A 402-MHz fully differential RF front-end was designed and implemented using 0.13 μ m CMOS process. This design was targeted for low-power and low-cost direct conversion applications such as short-range radio in biomedical devices. This RF front-end consists of a differential CG-CS LNA with a positive-or negative-feedback technique and a frequency doubler subharmonic quadrature passive mixer. The subharmonic conversion passive mixer driven by current input signals (from a transconductor) and loaded with low impedance is implemented to minimize the LO self-mixing dc-offset and introduces a high linearity. The front-end was implemented on a 0.13 μ m CMOS process and occupies 380 μ m × \330 μ m active chip area, which is approximately 50% of that of the conventional front-end. The RF front-end achieves 31 dB conversion gain, 13.6 dB noise figure (NF) and an in-band IIP3 of 3 dBm. The design consumes 2.25 mA from a 1.2 V power supply. © 2004-2012 IEEE.


Hoffmann D.,HSG IMIT Institute of Micromachining and Information Technology | Willmann A.,HSG IMIT Institute of Micromachining and Information Technology | Folkmer B.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,Albert Ludwigs University of Freiburg
Journal of Physics: Conference Series | Year: 2014

This paper reports on a new tuning concept, which enables the operation of a vibration generator for energy autonomous condition monitoring of maritime gearboxes. The tuning concept incorporates a circular tuning magnet, which interacts with a coupling magnet attached to the active transducer element. The tuning range can be tailored to the application by careful design of the gap between tuning magnet and coupling magnet. A total rotation angle of only 180° is required for the tuning magnet in order to obtain the full frequency bandwidth. The tuning concept is successfully demonstrated by charging a 0.6 F capacitor on the basis of physical vibration profiles taken from a gearbox. © Published under licence by IOP Publishing Ltd.


Hoffmann D.,HSG IMIT Institute of Micromachining and Information Technology | Folkmer B.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology
Journal of Physics: Conference Series | Year: 2013

In this paper we present an energy autonomous sensor system fully integrated into the heel of a shoe for biometric data monitoring. For powering the wireless sensor system a pulse-driven energy harvester was developed, which uses the acceleration-impulses from heel-strike during walking. In preparation of the device development acceleration measurements were carried out. The pulse-driven energy harvester is based on the electromagnetic conversion principle and incorporates a 4×4 coil matrix. A beam fixed at both ends is used for suspending the magnetic circuit. The geometric parameters of coil and magnetic circuit were optimized for maximum power output. For an idealized acceleration pulse with a width of 5 ms and a height of 200 m/s2 an average power output of 0.7 mW was generated using a step frequency of 1 Hz. The functionality of the self-sustained sensor system is demonstrated by measuring the temperature and step-frequency of a walking person and transmitting the data to a base station. We also found that the implementation of the suspension can have a significant impact on the harvester performance reducing the power output. © Published under licence by IOP Publishing Ltd.


Ylli K.,HSG IMIT Institute of Micromachining and Information Technology | Hoffmann D.,HSG IMIT Institute of Micromachining and Information Technology | Folkmer B.,HSG IMIT Institute of Micromachining and Information Technology | Manoli Y.,HSG IMIT Institute of Micromachining and Information Technology
Journal of Physics: Conference Series | Year: 2013

The concept of energy harvesting has been in the focus of research for more than two decades now and with the continuous device miniaturization and reduction in power consumption of the electronics it has become a viable power source for mobile systems. The increasing desire for mobility and longevity in terms of battery life has eventually led to wearable systems, i.e. electronic circuits with their power supply which are being integrated into textiles and everyday life. This paper reports the development of a cylindrical inductive energy harvesting device which exploits the accelerations available in the plane of the foot during walking. The modeling and characterization of the system is based upon real-world acceleration data recorded during treadmill runs. Although a wider range of test subjects would be required to increase the statistical relevance of the measured data, it is concluded that the energy provided by this system is sufficient to power low energy circuits at comparatively slow walking velocities. Additionally, the obtained knowledge can be used to develop a smaller, parallelized system. © Published under licence by IOP Publishing Ltd.


Hoffmann D.,HSG IMIT Institute of Micromachining and Information Technology | Willmann A.,HSG IMIT Institute of Micromachining and Information Technology | Gopfert R.,HSG IMIT Institute of Micromachining and Information Technology | Becker P.,HSG IMIT Institute of Micromachining and Information Technology | And 2 more authors.
Journal of Physics: Conference Series | Year: 2013

In this paper a rotational, radial-flux energy harvester incorporating a three-phase generation principle is presented for converting energy from water flow in domestic water pipelines. The energy harvester together with a power management circuit and energy storage is used to power a smart metering system installed underground making it independent from external power supplies or depleting batteries. The design of the radial-flux energy harvester is adapted to the housing of a conventional mechanical water flow meter enabling the use of standard components such as housing and impeller. The energy harvester is able to generate up to 720 mW when using a flow rate of 20 l/min (fully opened water tab). A minimum flow rate of 3 l/min is required to get the harvester started. In this case a power output of 2 mW is achievable. By further design optimization of the mechanical structure including the impeller and magnetic circuit the threshold flow rate can be further reduced. © Published under licence by IOP Publishing Ltd.

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