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  • 1.
    Arndt, Holger
    et al.
    Spring Techno GmbH & Co, Germany..
    Burkard, Stefan
    Spring Techno GmbH & Co, Germany..
    Talavera, Guillermo
    Universitat Autònoma de Barcelona, Spain.
    Garcia, Joan
    Universitat Autònoma de Barcelona, Spain.
    Castells, David
    Universitat Autònoma de Barcelona, Spain.
    Codina, Marc
    Universitat Autònoma de Barcelona, Spain.
    Hausdorff, Jeffrey
    Mirelman, Anat
    Tel Aviv Sourasky Medical Center, Israel.
    Harte, Richard
    National University of Ireland, Ireland.
    Casey, Monica
    National University of Ireland, Ireland.
    Glynn, Liam
    National University of Ireland, Ireland.
    Di Rosa, Mirko
    Istituto Nazionale Riposo e Cura per Anziani, Italy.
    Rossi, Lorena
    Istituto Nazionale Riposo e Cura per Anziani, Italy.
    Stara, Vera
    Istituto Nazionale Riposo e Cura per Anziani, Italy.
    Rösevall, John
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Rusu, Cristina
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Carenas, Carlos
    EURECAT, Spain.
    Breuil, Fanny
    EURECAT, Spain.
    Reixach, Elisenda
    EURECAT, Spain.
    Carrabina, Jordi
    Universitat Autònoma de Barcelona, Spain.
    Real-time constant monitoring of fall risk index by means of fully-wireless insoles2017Conference paper (Refereed)
    Abstract [en]

    Constant monitoring of gait in real life conditions is considered the best way to assess Fall Risk Index (FRI) since most falls happen out of the ideal conditions in which clinicians are currently analyzing the patient's behavior. This paper presents the WIISEL platform and results obtained through the use of the first full-wireless insole devices that can measure almost all gait related data directly on the feet (not in the upper part of the body as most existing wearable solutions). The platform consists of a complete tool-chain: insoles, smartphone & app, server & analysis tool, FRI estimation and user access. Results are obtained by combining parameters in a personalized way to build individual fall risk index assessed by experts with the help of data analytics. New FRI has been compared with standards that validate the quality of its prediction in a statistically significant way. That qualitatively relevant information is being provided to the platform users, being either end-users/patients, relatives or caregivers and the related clinicians to ideally assess about their long term evolution. © 2017 The authors and IOS Press.

  • 2.
    Bjurström, Johan
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Chalmers University of Technology, Sweden.
    Ohlsson, Fredrik
    RISE Research Institutes of Sweden. Umeå University, Sweden.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Johansson, Christer
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Chalmers University of Technology, Sweden.
    Unified Modeling and Analysis of Vibration Energy Harvesters under Inertial Loads and Prescribed Displacements2022In: Applied Sciences: APPS, E-ISSN 1454-5101, Vol. 12, no 19Article in journal (Refereed)
    Abstract [en]

    In this paper, we extend the optimization analysis found in the current literature for single-degree-of-freedom vibrational energy harvesters. We numerically derive and analyze the optimization conditions based on unified expressions for piezoelectric and electromagnetic energy harvesters. Our contribution lies in the detailed analysis and comparison of both resonant and anti-resonant states while fully including the effect of intrinsic resistance. We include both the case of excitation by inertial load and prescribed displacement, as the latter has not been elaborated on in the previous literature and provides new insights. We perform a general analysis but also consider typical values of applied piezoelectric and electromagnetic energy harvesters. Our results improve upon previous similar comparative studies by providing new and useful insights regarding optimal load, load power and power input to output efficiency. Our analysis shows an exponential increase in the critical mechanical quality factor due to the resistive loss coefficient. We find that the ratio of mechanical quality factor to resistive loss coefficient, at resonance, increases drastically close to the theoretical maximum for load power. Under the same optimization conditions, an equivalent conclusion can be drawn regarding efficiency. We find that the efficiency at anti-resonance behaves differently and is equal to or larger than the efficiency at resonance. We also show that the optimal load coefficient at resonance has a significant dependence on the mechanical quality factor only when the resistive loss coefficient is large. Our comparison of excitation types supports the previous literature, in a simple and intuitive way, regarding optimal load by impedance matching and power output efficiency. Our modeling and exploration of new parameter spaces provide an improved tool to aid the development of new harvester prototypes.

  • 3.
    Bjurström, Johan
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Chalmers University of Technology, Sweden .
    Ohlsson, Fredrik
    RISE Research Institutes of Sweden. Umeå University, Sweden.
    Vikerfors, Andreas
    ReVibe Energy AB, Sweden.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Johansson, Christer
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Tunable spring balanced magnetic energy harvester for low frequencies and small displacements2022In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 259, article id 115568Article in journal (Refereed)
    Abstract [en]

    In this paper we present a novel concept to efficiently harvest vibrational energy at low frequencies and very small displacement. We describe and evaluate an electromagnetic energy harvester which generates power from a magnetic circuit with motion induced variations of an air gap. External vibrations induce oscillations of the gap length around an equilibrium point, due to a linear spring counteracting the magnetic force. The relative position of the spring can be adjusted to optimize the harvester output for excitation amplitude and frequency. A simulation model is built in COMSOL and verified by comparison with lab measurements. The simulation model is used to determine the potential performance of the proposed concept under both harmonic and non-harmonic excitation. Under harmonic excitation, we achieve a simulated RMS load power of 26.5 μW at 22 Hz and 0.028 g acceleration amplitude. From a set of comparable EH we achieve the highest theoretical power metric of 1712.2 µW/cm3/g2 while maintaining the largest relative bandwidth of 81.8%. Using measured non-harmonic vibration data, with a mean acceleration of 0.039 g, resulted in a mean power of 52 μW. Moreover, the simplicity and robustness of our design makes it a competitive alternative for use in practical situations. © 2022 The Author(s)

  • 4.
    Castillejo, Pedro
    et al.
    Universidad Politecnica de Madrid, Spain.
    Johansen, Gorm
    SINTEF, Norway.
    Cürüklü, Baran
    Mälardalen University, Sweden.
    Bilbao-Arechabala, Sonia
    Tecnalia, Spain.
    Fresco, Roberto
    CNR IMAMOTER, Italy.
    Martínez-Rodríguez, Belen
    Tecnalia, Spain.
    Pomante, Luigi
    Università degli Studi dell'Aquila, Italy.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Martínez-Ortega, Jose
    Universidad Politecnica de Madrid, Spain.
    Centofanti, Carlo
    Università degli Studi dell'Aquila, Italy.
    Hakojärvi, Mikko
    Mtech Digital Solutions Ltd, Finland.
    Santic, Marco
    Università degli Studi dell'Aquila, Italy.
    Häggman, Johanna
    Mtech Digital Solutions Ltd, Finland.
    Aggregate Farming in the Cloud: The AFarCloud ECSEL project2020In: Microprocessors and microsystems, ISSN 0141-9331, E-ISSN 1872-9436, Vol. 78, article id 103218Article in journal (Refereed)
    Abstract [en]

    Farming is facing many economic challenges in terms of productivity and cost-effectiveness. Labor shortage partly due to depopulation of rural areas, especially in Europe, is another challenge. Domain specific problems such as accurate monitoring of soil and crop properties and animal health are key factors for minimizing economical risks, and not risking human health. The ECSEL AFarCloud (Aggregate Farming in the Cloud) project will provide a distributed platform for autonomous farming that will allow the integration and cooperation of agriculture Cyber Physical Systems in real-time in order to increase efficiency, productivity, animal health, food quality and reduce farm labor costs. Moreover, such a platform can be integrated with farm management software to support monitoring and decision-making solutions based on big data and real-time data mining techniques. © 2020 The Author(s)

  • 5.
    Johannisson, Pontus
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ohlsson, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Rusu, Cristina
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Impact-driven up-conversion in piezoelectric MEMS energy harvesters with pulsed excitation2018In: Journal of Physics: Conference Series, 2018, no 1, article id 012106Conference paper (Refereed)
    Abstract [en]

    The potential of impact-driven frequency up-conversion in a MEMS EH is evaluated using numerical simulations. The investigated design is compared to a conventional cantilever EH in terms of output power and loss rate. The upshifting can lead to significantly increased output power at a similar loss rate but as the time scale for the loss is long, the benefit is limited. This also requires an effective upshifting process. The design of the impact introduces a length scale that must be selected with excitation, gravity, and pre-stress taken into account. This makes this type of EH application-dependent as a non-optimal choice may result in low output power.

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  • 6.
    Johannisson, Pontus
    et al.
    RISE, Swedish ICT, Acreo.
    Ohlsson, Fredrik
    RISE, Swedish ICT, Acreo.
    Rusu, Cristina
    RISE, Swedish ICT, Acreo.
    Multi-axis piezoelectric energy harvesting using MEMS components with slanted beams2016In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 773, no 1, article id 012080Article in journal (Refereed)
    Abstract [en]

    During the manufacturing of MEMS components, slanted beams can be produced in the etching process. We show that this can be used to produce skew motion that causes deflection of a proof mass out of the device plane also when the excitation is confined to the device plane. This allows construction of an energy harvester that uses a planar manufacturing process and produces power also with in-plane excitation. To obtain this with traditional methods it would be necessary to manufacture separate components and then mount them with their sensitive axes orthogonal to each other.

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  • 7.
    Köhler, E.
    et al.
    Chalmers University of Technology, Sweden.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Kolev, Dimitar
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Ohlsson, Fredrik
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Ågren, P.
    Silex Microsystems, Sweden.
    Liljeholm, J.
    Silex Microsystems, Sweden.
    Enoksson, P.
    Chalmers University of Technology, Sweden.
    Rusu, Cristina
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    MEMS meander harvester with tungsten proof-mass2019In: Journal of Physics: Conference Series, Institute of Physics Publishing , 2019, no 1Conference paper (Refereed)
    Abstract [en]

    Using current battery technology the life-time of a leadless pacemaker is approximately 6-10 years, with a large portion of the pacemaker occupied by the battery. This paper investigates the possibility to use a MEMS piezoelectric harvester as a complementary energy source in leadless pacemakers. The challenge is to combine the low resonance frequency required to harvest energy from a heartbeat with the small volume of 20×4×3 mm3 available, with the corresponding harvester displacement restricted to 2 mm. Due to the displacement restriction the selected structure was a double clamped bridge in order to reduce the mass displacement, with various meander-type designs simulated to reduce resonance frequency. To further reduce resonance frequency large proof-masses of tungsten were attached by gluing. Two types of tungsten proof-masses were added to four different harvesters, 16.4 mg and 16.6 mg on sample 1 and 2 and 502 mg and 492 mg proof-mass on sample 3 and 4. The structures have 2 μm patterned PZT (deposited by sol-gel technique) and Pt metal electrodes for d31 mode harvesting. The power output measured from one of the two PZT/electrodes was 0.13 nW with 50 μm deflection at 100 k Ω optimal load resistance and 9.1 mVpp at 232 Hz.

  • 8.
    Larsson, S.
    et al.
    Linköping University, Sweden.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Kolev, D
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ohlsson, F
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nik, S.
    Liljeholm, J.
    Ebefors, T.
    Rusu, Cristina
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Simple method for quality factor estimation in resonating MEMS structures2018In: Proceedings of the 17th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications, 2017, 2018, no 1Conference paper (Refereed)
    Abstract [en]

    The quality factor of a packaged MEMS resonating structure depends on both the packaging pressure and the structure's proximity to the walls. This type of mechanical constraints, which causes energy dissipation from the structure to the surrounding air, are applicable for oscillating energy harvesters and should be considered in the design process. However, the modelling of energy losses or the measurements of their direct influence inside a packaged chip is not trivial. In this paper, a simple experimental method to quantify the energy loss in an oscillating MEMS structures due to the surrounding air is described together with preliminary results. The main advantage of the method is the ability to characterize the damping contributions under different vacuum and packaging conditions without requiring any packaging of the harvester chip or fabrication of multiple devices with different cavity depths. © Published under licence by IOP Publishing Ltd.

  • 9.
    Montagnoli, Antonio
    et al.
    University of Insubria, Italy.
    Terzaghi, Mattia
    University of Insubria, Italy.
    Fulgaro, Nicoletta
    University of Insubria, Italy.
    Stoew, Borys
    RISE, Swedish ICT, Acreo.
    Wipenmyr, Jan
    RISE, Swedish ICT, Acreo.
    Ilver, Dag
    RISE, Swedish ICT, Acreo.
    Rusu, Cristina
    RISE, Swedish ICT, Acreo.
    Scippa, Gabriella S.
    University of Molise, Italy.
    Chiatante, Donato
    University of Insubria, Italy.
    Non-destructive phenotypic analysis of early stage tree seedling growth using an automated stereovision imaging method2016In: Frontiers in Plant Science, E-ISSN 1664-462X, Vol. 7, article id 1644Article in journal (Refereed)
    Abstract [en]

    A plant phenotyping approach was applied to evaluate growth rate of containerized tree seedlings during the precultivation phase following seed germination. A simple and affordable stereo optical system was used to collect stereoscopic red-green-blue (RGB) images of seedlings at regular intervals of time. Comparative analysis of these images by means of a newly developed software enabled us to calculate (a) the increments of seedlings height and (b) the percentage greenness of seedling leaves. Comparison of these parameters with destructive biomass measurements showed that the height traits can be used to estimate seedling growth for needle-leaved plant species whereas the greenness trait can be used for broad-leaved plant species. Despite the need to adjust for plant type, growth stage and light conditions this new, cheap, rapid, and sustainable phenotyping approach can be used to study large-scale phenome variations due to genome variability and interaction with environmental factors.

  • 10.
    Ohlsson, Fredrik
    et al.
    RISE Research Institutes of Sweden. Chalmers University of Technology, Sweden; University of Gothenburg, Sweden; Umeå University, Sweden.
    Johannisson, Pontus
    RISE Research Institutes of Sweden.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Geometrical nonlinearities and shape effects in electromechanical models of piezoelectric bridge structures2021In: International Journal of Energy and Environmental Engineering, ISSN 2008-9163, E-ISSN 2251-6832, Vol. 12, p. 725-Article in journal (Refereed)
    Abstract [en]

    We consider nonlinear shape effects appearing in the lumped electromechanical model of a bimorph piezoelectric bridge structure due to the interaction between the electromechanical constitutive model and the geometry of the structure. At finite proof-mass displacement and electrode voltage, the shape of the beams is no longer given by Euler-Bernoulli theory which implies that shape effects enter in both the electrical and mechanical domains and in the coupling between them. Accounting for such effects is important for the accurate modelling of, e.g., piezoelectrical energy harvesters and actuators in the regime of large deflections and voltages. We present a general method, based on a variational approach minimizing the Gibbs enthalpy of the system, for computing corrections to the nominal shape function and the associated corrections to the lumped model. The lowest order correction is derived explicitly and is shown to produce significant improvements in model accuracy, both in terms of the Gibbs enthalpy and the shape function itself, over a large range of displacements and voltages. Furthermore, we validate the theoretical model using large deflection finite element simulations of the bridge structure and conclude that the lowest order correction substantially improve the model, obtaining a level of accuracy expected to be sufficient for most applications. Finally, we derive the equations of motion for the lowest order corrected model and show how the coupling between the electromechanical properties and the geometry of the bridge structure introduces nonlinear interaction terms. © 2021, The Author(s).

  • 11.
    Ohlsson, Fredrik
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Rusu, Cristina
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Shape effects in doubly clamped bridge structures at large deflections2018In: Journal of Physics: Conference Series, 2018, Vol. 1052, no 1Conference paper (Refereed)
    Abstract [en]

    The shape of a doubly clamped bridge structure depends on its deflection. At large deflections, where the system exhibits nonlinear behaviour, the shape effect becomes significant. We present a general method, based on variational analysis, for computing corrections to the nominal linear regime shape function. The method is used to compute the first non-trivial correction and quantify the corresponding improvement in the large deflection regime. The model obtained is also validated using FEM simulations.

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  • 12.
    Ohlsson, Fredrik
    et al.
    RISE, Swedish ICT, Acreo.
    Olsson, Erik
    RISE, Swedish ICT, Acreo.
    Rusu, Cristina
    RISE, Swedish ICT, Acreo.
    Modelling squeeze film damping in packaged energy harvesters2015In: 2015 European Conference on Circuit Theory and Design (ECCTD), 2015, article id 7300115Conference paper (Refereed)
    Abstract [en]

    We investigate the effects of fluidic damping on MEMS packaged energy harvesters using numerical simulations in COMSOL Multiphysics. In particular, we compare two models for including squeeze film damping in the case where the harvester is operating close to a wall; an equivalent mass damping based on approximate modal coefficients and the numerical solution of the Reynolds equation in the air gap between the wall and the structure. The models are evaluated on a bridge design harvester intended for automotive applications.

  • 13.
    Pamfil, Bogdan
    et al.
    Chalmers University of Technology, Sweden.
    Palm, Richard
    Chalmers University of Technology, Sweden.
    Vyas, Agin
    Chalmers University of Technology, Sweden.
    Staaf, Henrik
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Folkow, Peter D.
    Chalmers University of Technology, Sweden.
    Multi-Objective Design Optimization of Fractal-based Piezoelectric Energy Harvester2021In: 2021 IEEE 20th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), 2021, p. 96-99Conference paper (Refereed)
    Abstract [en]

    This paper studies optimization solutions for a proof-of-concept design methodology for a fractal-based tree energy harvester with a stress distribution optimized structure. The focus is on obtaining a sufficiently high-power output and a high enough stress in the longitudinal branch direction by using Frequency Response Functions. The design methodology shows that using the MATLAB code with Sensitivity Analysis and Multi-objective Optimization in combination with elitist genetic algorithm enables an optimal design.

  • 14.
    Romani, Aldo
    et al.
    University of Bologna, Italy.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Staaf, Henrik
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Avetisova, Ksenia
    TietoEVRY, Finland.
    The ENERGY ECS Project: Smart and Secure Energy Solutions for Future Mobility2023In: 2023 AEIT International Conference on Electrical and Electronic Technologies for Automotive (AEIT AUTOMOTIVE), IEEE , 2023Conference paper (Refereed)
    Abstract [en]

    Electric and smart mobility are key enablers for their green energy transition. However, the electrification of vehicles poses several challenges, from the development of power components to the organization of the electric grid system. Moreover, it is expected that the smartification of mobility via sensors and novel transport paradigms will play an essential role in the reduction of the consumed energy. In response to these challenges and expectations, the ENERGY ECS project is pursuing smart and secure energy solutions for the mobility of the future, by developing power components, battery charging electronics, and self-powered sensors for condition monitoring, along with advanced techniques for grid management, applications of artificial intelligence, machine learning and immersing technologies. This paper presents the project’s objectives and reports intermediate results from the perspective of the targeted use cases.

  • 15.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Miniaturised Energy Harvesting @ RISE2022Conference paper (Other academic)
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  • 16.
    Rusu, Cristina
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Bader, S.
    Mid Sweden University, Sweden.
    Oelmann, B.
    Mid Sweden University, Sweden.
    Alvandpour, A.
    Linköping University, Sweden.
    Enoksson, P.
    Chalmers University of Technology, Sweden.
    Braun, T.
    Fraunhofer, Germany.
    Tiedke, S.
    aixACCT Systems GmbH, Germany.
    Dal Molin, R.
    Cairdac, France.
    Ferin, G.
    Vermon SA, France.
    Torvinen, P.
    Spinverse Innovation Management Oy, Finland.
    Liljeholm, J.
    Silex Microsystems AB, Sweden.
    Challenges for Miniaturised Energy Harvesting Sensor Systems2019In: 2018 10th International Conference on Advanced Infocomm Technology, ICAIT 2018, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 214-217Conference paper (Refereed)
    Abstract [en]

    Harvesting ambient energy, as an alternative power source, tackles the increasing demand for future energy-efficient autonomous sensor systems, especially for applications requiring miniaturisation and distributed sensing such Wireless Sensors Network and Internet-of-Things. A functional energy harvesting system requires addressing simultaneously all the components of the system: the harvester device, the energy storage and the powering management circuits. These components are described through examples of miniaturized kinetic-based harvesting systems for low-power applications with focus on energy harvester, piezoelectric and electromagnetic, respectively.

  • 17.
    Rusu, Cristina
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Krozer, Anatol
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Ahrentorp, Fredrik
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Pettersson, Torbjörn
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Rösevall, John
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Ilver, Dag
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Terzaghi, Mattia
    University of Insubria, Italy.
    Chiatante, Donato
    University of Insubria, Italy.
    Montagnoli, Antonio
    University of Insubria, Italy.
    Miniaturized wireless water content and conductivity soil sensor system2019In: Computers and Electronics in Agriculture, ISSN 0168-1699, E-ISSN 1872-7107, Vol. 167, article id 105076Article in journal (Refereed)
    Abstract [en]

    Obtaining more data for the research/studies of plants growing may be easier realized when suitable non-destructive detection methods are available. We are here presenting the development of a miniaturised, low-power, real-time, multi-parameter and cost-effective sensor for measurements in mini plugs (growth of seedling). The detection technique is based on measurement of electrical impedance at two frequencies for sensing two soil parameters, water content and water conductivity (dependent on e.g. total ions concentration). Electrical models were developed and comply with data at two frequencies. An easy and efficient calibration method for the sensor is established by using known liquids’ properties instead of various soil types. The measurements show a good correlation between the sensor's readings and the traditional soil testing. This soil sensor can easily send data wirelessly allowing for spot checks of substrate moisture levels throughout a greenhouse/field, and/or enable sensors to be buried inside the soil/substrate for long-term consecutive measurements.

  • 18.
    Staaf, Henrik
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Matsson, Simon
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Sepheri, Sobhan
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Köhler, Elof
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Daoud, Kaies
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Breas AB, Sweden.
    Ahrentorp, Fredrik
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Jonasson, Christian
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Folkow, Peter
    Chalmers University of Technology, Sweden.
    Ryynänen, Leena
    Nokian Tyres Plc, Finland.
    Penttila, Mika
    Nokian Tyres Plc, Finland.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Simulated and measured piezoelectric energy harvesting of dynamic load in tires2024In: Heliyon, E-ISSN 2405-8440, Vol. 10, no 7, article id e29043Article in journal (Refereed)
    Abstract [en]

    From 2007 in US and from 2022 in EU it is mandatory to use TPMS monitoring in new cars. Sensors mounted in tires require a continuous power supply, which currently only is from batteries. Piezoelectric energy harvesting is a promising technology to harvest energy from tire movement and deformation to prolong usage of batteries and even avoid them inside tires. This study presents a simpler method to simultaneous model the tire deformation and piezoelectric harvester performance by using a new simulation approach - dynamic bending zone. For this, angular and initial velocities were used for rolling motion, while angled polarization was introduced in the model for the piezoelectric material to generate correct voltage from tire deformation. We combined this numerical simulation in COMSOL Multiphysics with real-life measurements of electrical output of a piezoelectric energy harvester that was mounted onto a tire. This modelling approach allowed for 10 times decrease in simulation time as well as simpler investigation of systems parameters influencing the output power. By using experimental data, the simulation could be fine-tuned for material properties and for easier extrapolation of tire deformation with output harvested energy from simulations done at low velocity to the high velocity experimental data.

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  • 19.
    Staaf, Henrik
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Sawatdee, Anurak
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Nilsson, David
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Schäffner, Philipp
    Joanneum Research Forschungsgesellschaft mbH, Austria.
    Johansson, Christer
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    High magnetoelectric coupling of Metglas and P(VDF-TrFE) laminates2022In: Scientific Reports, Vol. 12, no 1, article id 5233Article in journal (Refereed)
    Abstract [en]

    Magnetoelectric (magnetic/piezoelectric) heterostructures bring new functionalities to develop novel transducer devices such as (wireless) sensors or energy harvesters and thus have been attracting research interest in the last years. We have studied the magnetoelectric coupling between Metglas films (2826 MB) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) in a laminate structure. The metallic Metglas film itself served as bottom electrode and as top electrode we used an electrically conductive polymer, poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). Besides a direct electrical wiring via a graphite ink, a novel contactless readout method is presented using a capacitive coupling between the PEDOT:PSS layer and an electrode not in contact with the PEDOT:PSS layer. From the experimental result we determined a magnetoelectric coupling of 1445 V/(cm·Oe) at the magnetoelastic resonance of the structure, which is among the highest reported values for laminate structures of a magnetostrictive and a piezoelectric polymer layer. With the noncontact readout method, a magnetoelectric coupling of about 950 V/(cm·Oe) could be achieved, which surpasses previously reported values for the case of direct sample contacting. 2D laser Doppler vibrometer measurements in combination with FE simulations were applied to reveal the complex vibration pattern resulting in the strong resonant response.

  • 20.
    Talavera, Guillermo
    et al.
    Autonomous University of Barcelona, Spain.
    Garcia, Joan
    Autonomous University of Barcelona, Spain.
    Rösevall, John
    RISE, Swedish ICT, Acreo.
    Rusu, Cristina
    RISE, Swedish ICT, Acreo.
    Carenas, Carlos
    CETEMMSA, Spain.
    Breuil, Fanny
    CETEMMSA, Spain.
    Reixach, Elisenda
    CETEMMSA, Spain.
    Arndt, Holger
    Spring Techno GmbH & Co. KG, Germany.
    Burkard, Stefan
    Spring Techno GmbH & Co. KG, Germany.
    Harte, Richie
    National University of Ireland, Ireland.
    Glynn, Liam
    National University of Ireland, Ireland.
    Carrabina, Jordi
    Autonomous University of Barcelona, Spain.
    Fully-wireless sensor insole as non-invasive tool for collecting gait data and analyzing fall risk2015In: Ambient Intelligence for Health / [ed] José Bravo, Ramón Hervás, Vladimir Villarreal, 2015, Vol. 9456, p. 15-25Conference paper (Refereed)
    Abstract [en]

    This paper presents the final results and future projection of the European project WIISEL (Wireless Insole for Independent and Safe Elderly Living), that reached to build the first full-wireless insole (that include both wireless communication and wireless charging). These insoles provide a new set of non-invasive tools that can be used either at the clinical installations or at home. That solution improves the usability and user experience compared with traditional tools (smart carpets, wired insoles, etc.) that are oriented to clinical installations. And hence, provide a powerful tool for Ambient Intelligent for Health, especially for elderly people, increasing their autonomy and providing means for long term monitoring. Health parameters analysed are fall risk and gait analysis. Both are assessed on the establishment of clinical parameters such as fall risk index, and gait pattern and fall detection and algorithms. All those can be obtained thanks to our fully-wireless flexible insole that contains the sensors, embedded processing and wireless communications and charging. Pressure and inertial sensors are embedded into the insoles and a smartphone collects data utilizing Bluetooth Low Energy that is later sent to a main server analysis for its management, analysis and storage. This provides the selected information to the corresponding platform users being either end-users/patients, their relatives or caregivers and the related clinicians.

  • 21.
    Vyas, Agin
    et al.
    Chalmers University of Technology, Sweden.
    Staaf, Henrik
    Chalmers University of Technology, Sweden.
    Rusu, Cristina
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Ebefors, Thorbjörn
    MyVox AB, Sweden.
    Liljeholm, Jessica
    Silex Microsystems AB, Sweden.
    Smith, Anderson
    Chalmers University of Technology, Sweden.
    Lundgren, Per
    Chalmers University of Technology, Sweden.
    Enoksson, Peter
    Chalmers University of Technology, Sweden.
    A micromachined coupled-cantilever for piezoelectric energy harvesters2018In: Micromachines, E-ISSN 2072-666X, Vol. 9, no 5, article id 252Article in journal (Refereed)
    Abstract [en]

    This paper presents a demonstration of the feasibility of fabricating micro-cantilever harvesters with extended stress distribution and enhanced bandwidth by exploiting an M-shaped two-degrees-of-freedom design. The measured mechanical response of the fabricated device displays the predicted dual resonance peak behavior with the fundamental peak at the intended frequency. This design has the features of high energy conversion efficiency in a miniaturized environment where the available vibrational energy varies in frequency. It makes such a design suitable for future large volume production of integrated self powered sensors nodes for the Internet-of-Things

1 - 21 of 21
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