References of "Kraft, Michaël"
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See detail355nm UV laser patterning and post-processing of FR4 PCB for fine pitch components integration
Dupont, François ULiege; Stoukatch, Serguei ULiege; Laurent, Philippe ULiege et al

in Optics and Lasers in Engineering (2018), 100

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See detailSmart-shoes self-powered by walking
Colson, Gérald ULiege; Laurent, Philippe ULiege; Bellier, Pierre ULiege et al

Poster (2017, May 10)

Nowadays, electronic devices are more and more compact and can be integrated in nearly every object. One of the remaining challenges is to provide smarter ways to power those electronic devices. Because ... [more ▼]

Nowadays, electronic devices are more and more compact and can be integrated in nearly every object. One of the remaining challenges is to provide smarter ways to power those electronic devices. Because of the small amount of energy needed by the latest ultra-low power systems, energy harvesting from the environment becomes a viable solution to power them. In this work, we present the integration of an electronic device and an electrodynamic energy harvester (EH) in a shoe. The electronic device measures the acceleration along one axis at a sampling rate of 30 Hz and sends the data every second using a wireless link. The data are then collected by a gateway and processed to count the number of steps, calculate the contact time and the flying time of the foot. To perform this function, the device requires an average power of 951 μW which is provided by the EH. [less ▲]

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See detailDroplet formation by squeezing in a microfluidic cross-junction
Van Loo, Stéphanie ULiege; Stoukatch, Serguei ULiege; Kraft, Michael ULiege et al

in Microfluidics and Nanofluidics (2016), 20(10), 1-12

In microfluidics, flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. We here report an experimental study of droplet formation in a microfluidic cross ... [more ▼]

In microfluidics, flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. We here report an experimental study of droplet formation in a microfluidic cross-junction with a minimum number of geometrical parameters. We mostly focus on the squeezing regime, which is composed of two distinct steps : filling and pinching. The duration of each step (and corresponding volumes of each liquid phase) are analyzed. They vary according to both water and oil flow rates. These variations provide several insights about the fluid flows in both phases. We propose several scaling laws to relate the droplet volume and frequency to the flow rate of both phases. We also discuss the influence of surfactant and channel compliance on droplet formation. [less ▲]

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See detailHow do droplets form?
Van Loo, Stéphanie ULiege; Stoukatch, Serguei ULiege; Kraft, Michael ULiege et al

Poster (2016, September 07)

In microfluidics, flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. We here report an experimental study of droplet formation in a microfluidic cross ... [more ▼]

In microfluidics, flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. We here report an experimental study of droplet formation in a microfluidic cross-junction with a minimum number of geometrical parameters. We mostly focus on the squeezing regime, which is com- posed of two distinct steps : filling and pinching. The duration of each step (and corresponding volumes of each liquid phase) are analyzed. They vary according to both water and oil flow rates. These variations provide several insights about the fluid flows in both phases. We propose several scaling laws to relate the droplet volume and frequency to the flow rate of both phases. We also discuss the influence of surfactant and channel compliance on droplet formation. [less ▲]

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See detailMass sensor utilising the mode-localisation effect in an electrostatically-coupled MEMS resonator pair fabricated using an SOI process
Wood, Graham; Chun, Zhao; Pu, Suan et al

in Microelectronic Engineering (2016), 159

The change in the mass, achieved with focused ion beam(FIB) milling, of one of a pair of electrostatically-coupled microelectromechanical systems (MEMS) resonators has been detected utilising the mode ... [more ▼]

The change in the mass, achieved with focused ion beam(FIB) milling, of one of a pair of electrostatically-coupled microelectromechanical systems (MEMS) resonators has been detected utilising the mode-localisation effect. It has been demonstrated that the shift in the amplitude ratio of the coupled-resonators at the in-phase mode frequency, in response to a mass change, is five orders of magnitude greater than the equivalent resonant frequency shift of a single resonator device. The device has been fabricated using a silicon-on-insulator (SOI) based process, which allows for high-yield and stiction-free fabrication. In addition, the design of the resonators has been created to have a larger surface area than previously reported designs, in order to facilitate future biological functionalisation. The mass sensitivity has been compared to current state-of-the-art mode-localised mass sensors and a 5.4 times increase in the amplitude ratio response to a given mass change has been demonstrated for the device in this work. [less ▲]

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See detailMechanically-coupled ring-resonator filter and array (analytical and finite element model).
Pachkawade, Vinayak ULiege; Junghare, R; Patrikar, R et al

in IET Computers and Digital Techniques (2016)

In this paper, a design of two microelectromechanical systems based devices is carried out using an analytical and finite-element analysis. The first device is mechanically coupled ring-resonator band ... [more ▼]

In this paper, a design of two microelectromechanical systems based devices is carried out using an analytical and finite-element analysis. The first device is mechanically coupled ring-resonator band-pass filter with centre frequency of 4.4 MHz and a small bandwidth of only 36 kHz. Flexural-mode ring resonators have been mechanically coupled using soft mechanical spring for realising the filtering action. Owing to inherent symmetry in the ring structure, simple approach is used to access a low-velocity coupling locations to set a smallest possible bandwidth. The authors also show a reduction in the amplitude of spurious mode by accentuating the filter structure in its fully differential mode inherently present in the structure. Moreover, the effect of the number of the support beams and structural damping on the frequency response of a filter has been analysed. A second device is mechanically coupled ring-resonator arrays with varying number of rings coupled. The mechanical links using short stubs connect each constituent resonator of an array to its adjacent ones at the high-velocity vibrating locations to accentuate the desired mode and reject all other spurious modes. Both analytical and finite-element based simulation results for parameters of the designed structure are found in good agreement. [less ▲]

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See detailIntegrated multi-sensor system for parallel in-situ monitoring of cell nutrients, metabolites, cell density and pH in biotechnological processes
Mross, Stefan; Zimmermann, Tom; Winkin, N et al

in Sensors and Actuators. B, Chemical (2016)

We report on a multi-sensor system for the parallel in-situ monitoring of cell nutrients, metabolites, cell density and pH in biotechnological processes. The fabrication process of the sensor chip, based ... [more ▼]

We report on a multi-sensor system for the parallel in-situ monitoring of cell nutrients, metabolites, cell density and pH in biotechnological processes. The fabrication process of the sensor chip, based on a CMOS process flow, is suitable for integration into standard processes and mass production of the system. The integration of enzyme sensors for wide concentration ranges, an impedance-based sensor and a pH sensor on one silicon chip for in-situ applications in bioreactors, fabricated in a CMOS-based process flow, is demonstrated for the first time to our best knowledge. Measurements of glucose and lactate concentrations in a wide range are shown with linear ranges up to 600 mMand 900 mM, respectively. Cell density is determined via conductivity changes of a cell suspension and measurements are performed up to 15 g/l dry cell weight. The pH sensor is based on C-V measurements at an electrolyte-insulator semiconductor structure and able to measure pHin a range from pH3 to pH12. All sensors are successfully employed in the monitoring of cultures of Saccharomyces cerevisiae or Lactobacillus acidophilus. [less ▲]

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See detailElectromechanical Sigma-Delta Modulators (EMSDM) force feedback interfaces for capacitive MEMS inertial sensors: a review
Chen, Fang; Li, Xinxin; Kraft, Michael ULiege

in IEEE Sensors Journal (2016)

Analog-to-digital converters (ADC) based on sigma-delta modulators (SDM) are a popular choice for high resolution conversion from the analog to the digital domain. With relatively small modifications they ... [more ▼]

Analog-to-digital converters (ADC) based on sigma-delta modulators (SDM) are a popular choice for high resolution conversion from the analog to the digital domain. With relatively small modifications they also can be used as electromechanical SDM (EM-SDM) force feedback interfaces for capacitive micro-electromechanical systems (MEMS) inertial sensors. Such interfaces are able to combine the benefits of force feedback and analog to digital conversion at relatively modest circuit cost. This paper provides a comprehensive review of EM-SDM interfaces for capacitive MEMS inertial sensors. The principle and design methodology of EM-SDM interfaces are introduced. A classification of EM-SDMaccelerometers and gyroscopes is presented, and a detailed analysis of different EM-SDMarchitectures is given. The most representative EM-SDM inertial sensors systems are discussed and compared with regard to their performance characteristics. In particular, the properties of various discrete and continuous-time techniques and a system parameter optimization methodology are illustrated through specific examples. Finally, current challenges and future development trends of EM-SDM interfaces for inertial sensors have been identified. [less ▲]

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See detailAn investigation of structural dimension variation in electrostatically-coupled MEMS resonator pairs using mode-localization
Wood, Graham; Chun, Zhao; Pu, Suan et al

in IEEE Sensors Journal (2016)

If a pair of MEMS resonators are electrostatically coupled together, the vibration amplitude ratios at the resonant frequencies of the resulting coupled system are sensitive to stiffness perturbation. An ... [more ▼]

If a pair of MEMS resonators are electrostatically coupled together, the vibration amplitude ratios at the resonant frequencies of the resulting coupled system are sensitive to stiffness perturbation. An imbalance between the two resonators causes the confinement of vibration energy when the system is resonating, an effect known as mode-localization. The degree of localization can be determined by extracting the amplitude ratio of the resonators through capacitive transduction. In this paper, we have fabricated MEMS devices, using a dicing-free silicon-on-insulator process, consisting of pairs of closely spaced microresonators. Each resonator consists of a clamped-clamped beam with a wider section in the middle, which is the location of the electrostatic coupling, instituted through the DC biasing of the resonators. Several devices have been fabricated, with the length of the anchor beams being varied, which influences the frequency of resonance. Stiffness imbalance between the resonators has been introduced through electrostatic spring softening, with the sensitivity of the amplitude ratio of the resonant mode shape being greater for the higher frequency, shorter anchor devices. The sensitivities of the devices in this study have been found to be 9 times greater than state-of-the-art two-degree-of-freedom mode-localized sensors. [less ▲]

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See detailComparative study of output metrics for A MEMS resonant sensor consisting of three weakly coupled resonators
Zhao, Chun; Wood, Graham; Xie, J.B. et al

in Journal of Microelectromechanical Systems (2016)

Abstract—This paper systematically investigates the characteristics of different output metrics for a weakly coupled three degree-of-freedom microelectromechanical systems resonant sensor. The key figures ... [more ▼]

Abstract—This paper systematically investigates the characteristics of different output metrics for a weakly coupled three degree-of-freedom microelectromechanical systems resonant sensor. The key figures-of-merit examined are sensitivity and linear range. The four main output metrics investigated are mode frequency shift, amplitude difference, amplitude ratio, and eigenstate shift. It is shown from theoretical considerations, equivalent RLC circuit model simulations and electrical measurements, that there is a strong tradeoff between sensitivity and linear range. For instance, the amplitude difference has the best sensitivity but the worst linear range, whereas frequency shift has the widest linear range but the lowest sensitivity. We also show that using the vibrational amplitude ratio as an output metric provides the best balance between sensitivity and linear range. [less ▲]

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See detailAn acceleration sensing method based on the mode localization of weakly coupled resonators
Zhang, H.M.; Yuan, W.Z.; Li, B.Y. et al

in Journal of Microelectromechanical Systems (2016), 25(2), 286-296

Abstract—This paper reports an acceleration sensing method based on two weakly coupled resonators (WCRs) using the phenomenon of mode localization. When acceleration acts on the proof masses, differential ... [more ▼]

Abstract—This paper reports an acceleration sensing method based on two weakly coupled resonators (WCRs) using the phenomenon of mode localization. When acceleration acts on the proof masses, differential electrostatic stiffness perturbations will be applied to the WCRs, leading to mode localization, and thus, mode shape changes. Therefore, acceleration can be sensed by measuring the amplitude ratio shift. The proposed mode localization with the differential perturbation method leads to a sensitivity enhancement of a factor of 2 than the common single perturbation method. The theoretical model of the sensitivity, bandwidth, and linearity of the accelerometer is established and verified. The measured relative shift in amplitude ratio (∼312162 ppm/g) is 302 times higher than the shift in resonance frequency (∼1035 ppm/g) within the measurement range of ±1g. The measured resolution based on the amplitude ratio is 0.619 mg and the nonlinearity is ∼3.5% in the open-loop measurement operation. [less ▲]

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See detailSensor based on the mode-localization effect in electrostatically-coupled MEMS resonators fabricated using an SOI process
Wood, Graham; Zhao, Chun; Pu, Suan et al

in Proceedings of the IEEE Sensors Conference, Nov. 2015 (2015, November)

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See detailMASH2-0 electromechanical sigma-delta modulator for capacitive MEMS sensors with digital filter calibration using simulated annealing
Almutairy, Bader; Kraft, Michael ULiege

in Proceedings of the IEEE Sensors Conference, Nov. 2015 (2015, November)

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See detailA feasibility study for a self-oscillating loop for a three degree of freedom coupled MEMS resonator force sensor
Zhao, C; Wood, GS; Pu, SH et al

in Proc. Eurosensors MP-L01 (2015, September)

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See detailIntegrated multi-sensor system for parallel in-situ monitoring of cell nutrients, metabolites and cell mass in biotechnological processes
Mross, S; Zimmerman, T; Winkin, N et al

in Proc. Eurosensors, CS02-1 (2015, September)

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See detailMass sensor utilising the mode-localisation effect in an electrostatically-coupled MEMS resonator pair fabricated using an SOI process
Wood, Graham; Chun, Zhao; Pu, Suan et al

in Proceedings 41st Micro and Nano Engineering Conference (2015, September)

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See detailDesign and implementation of a MASH2-0 Electromechanical Sigma-Delta Modulator for capacitive MEMS sensors using dual quantization method
Almutairi, Bader; Alsheri, Ali; Kraft, Michael ULiege

in Journal of Microelectromechanical Systems (2015)

In this paper, a new control structure based on the dual quantization technique is presented for an electromechanical sigma–delta modulator (EM-SD M) applied to a microelectromechanical system (MEMS ... [more ▼]

In this paper, a new control structure based on the dual quantization technique is presented for an electromechanical sigma–delta modulator (EM-SD M) applied to a microelectromechanical system (MEMS) accelerometer. The modulator adopts a 2-0 multistage noise shaping structure (MASH2-0), taking the advantage of the intrinsic linearity of single-bit quantization and the reduced quantization error of multibit quantization in a single modulator. The sensor system is studied by the system-level modeling and the hardware implementation based on the field-programmable gate array technology. The study shows that, MASH2-0 shares the benefits of a MASH2-2 architecture of having an inherent stability, a high overload input level, and a high dynamic range compared with single-loop EM-SD M. However, the MASH2-0 architecture benefits from a considerably simpler implementation, while achieving a higher dynamic range and a higher signal-to-noise ratio compared with a MASH2-2 and a fourth-order single-loop SDM architecture. A capacitive MEMS accelerometer was designed and employed with this control system. Within a bandwidth of 1 kHz, the sensor achieved a noise floor level of −130 dB and a bias instability as low as 20 μg at an integration time of 40 s. Simulation estimated a full scale of ±20 g acceleration. The investigation confirms the concept of the MASH2-0 structure and shows its potential as a closed-loop interface for high-performance capacitive MEMS accelerometers. [less ▲]

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See detailA force sensor based on three weakly coupled resonators with ultrahigh sensitivity
Zhao, Chun; Wood, Graham; Xie, J.B. et al

in Sensors and Actuators. A, Physical (2015), 232

A proof-of-concept force sensor based on three degree-of-freedom (DoF) weakly coupled resonatorswas fabricated using a silicon-on-insulator (SOI) process and electrically tested in 20 Torr vacuum.Compared ... [more ▼]

A proof-of-concept force sensor based on three degree-of-freedom (DoF) weakly coupled resonatorswas fabricated using a silicon-on-insulator (SOI) process and electrically tested in 20 Torr vacuum.Compared to the conventional single resonator force sensor with frequency shift as output, by measuringthe amplitude ratio of two of the three resonators, the measured force sensitivity of the 3DoF sensor was4.9 × 106/N, which was improved by two orders magnitude. A bias stiffness perturbation was applied toavoid mode aliasing effect and improve the linearity of the sensor. The noise floor of the amplitude ratiooutput of the sensor was theoretically analyzed for the first time, using the transfer function model ofthe 3DoF weakly coupled resonator system. It was shown based on measurement results that the outputnoise was mainly due to the thermal–electrical noise of the interface electronics. The output noise spectraldensity was measured, and agreed well with theoretical estimations. The noise floor of the force sensoroutput was estimated to be approximately 1.39nN for an assumed 10 Hz bandwidth of the output signal,resulting in a dynamic range of 74.8 dB. [less ▲]

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See detailComparative study of different output metrics for a three weakly coupled resonator sensor
Zhao, Chun; Wood, Graham; Xie, J.B. et al

in Proceedings of Solid-State Sensors, Actuators and Microsystems (Transducers 2015) (2015, July)

This work, for the first time, investigates the characteristics of different output metrics for a three degree-of-freedom (DoF) coupled resonator sensor. The main aspects examined are sensitivity and ... [more ▼]

This work, for the first time, investigates the characteristics of different output metrics for a three degree-of-freedom (DoF) coupled resonator sensor. The main aspects examined are sensitivity and linear range. It is shown from electrical measurements that using the vibration amplitude ratio as an output signal provides improved sensitivity and linearity range, compared to other methods such as shift in eigenstate, mode frequency or amplitude difference. [less ▲]

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See detailA novel resonant accelerometer based on model localization of weakly coupled resonators.
Zhang, Hemin; Yuan, W.Z.; Li, B.Y. et al

in Proceedings of Solid-State Sensors, Actuators and Microsystems (Transducers 2015) (2015, June)

This paper describes a novel MEMS resonant accelerometer based on two weakly coupled resonators (WCRs) using the phenomenon of mode localization. It is the first time that this principle is demonstrated ... [more ▼]

This paper describes a novel MEMS resonant accelerometer based on two weakly coupled resonators (WCRs) using the phenomenon of mode localization. It is the first time that this principle is demonstrated experimentally for an accelerometer. The measured relative shift in amplitude ratio (~312162 ppm/g) is 302 times higher than the shift in resonance frequency (~1035 ppm/g). [less ▲]

Detailed reference viewed: 74 (2 ULiège)