Now showing 1 - 10 of 112
  • Publication
    Forced Motion Activated Self-Alignment of Micro-CPV Solar Cells
    In micro-concentrating photovoltaics (micro-CPV), the size of solar cells is reduced (<1x1 mm 2 ) compared to conventional CPV. However, the quantity and requirement for placement accuracy of solar cells is increased. To be economically competitive, a promising possibility for the die assembly is a high throughput and relatively unprecise pick and place process combined with surface tension-driven self-alignment of the liquid solder. In this article, this approach is experimentally investigated, with a focus on the influences of solder volume, receiving pad layouts, and initial displacements of the cells on the self-alignment accuracy. Here, we show that an induced motion due to the initial displacement of the cells or due to solder flow along tracks leads to a more robust and accurate process. We found that less solder and rather smaller pads than cells (here by 92 μm or 10.4% of the cell length) are beneficial for self-alignment accuracy. However, for micro-CPV, conductor tracks connected to the pad are required for electrical interconnection and heat dissipation. Here, all cells are self-aligned and reach an accuracy between -15 and +15 μm, which is mainly due to the cell-to-pad size difference. Optical simulations show that this displacement would lead to an optical loss of 0.1% abs instead of 12.1% abs when displacing the cell by 150 μm. Thus, the self-alignment using the surface tension of the liquid solder leads to sufficient accuracy.
  • Publication
    Wie die Energiewende trotz des steigenden Rohstoffbedarfes gelingen kann
    Die Energiewende, welche aufgrund des voranschreitenden Klimawandels notwendig ist, erfordert den Einsatz neuer Technologien mit erhöhtem Rohstoffbedarf, um die ambitionierten Ziele der Klimapolitik zu erreichen. Doch wie können wir gewährleisten, dass die potenziell kritischen Rohstoffe auch in Zukunft zur Verfügung stehen?
  • Publication
    A forecast on future raw material demand and recycling potential of lithium-ion batteries in electric vehicles
    The market for electromobility has grown constantly in the last years. To ensure a future supply of raw materials for the production of new batteries for electric vehicles, it is essential to estimate the future demand for battery metals. This study focuses on the future demand for electric vehicle battery cathode raw materials lithium, cobalt, nickel, and manganese by considering different technology and growth scenarios. The results show that in 2040 the future material demand for lithium, cobalt, and nickel for Lithium-Ion Batteries in electric vehicles exceeds current raw material production. Depending on the growth and technology scenario, the future demand for lithium and cobalt exceeds today's production by up to 8 times in 2040. Nickel exceeds today's production in one scenario. For manganese, future demand in 2040 remains far below today's production. The recycling potential for lithium and nickel is more than half the raw material demand for Lithium-Ion Batteries in 2040. For cobalt, the recycling potential even exceeds the raw material demand in 2040. In conclusion, it remains a challenge for the industry to massively scale up resource production and focus on the recycling of battery metals in the future to meet the increasing consumption of electromobility.
  • Publication
    Sensor Systems for Extremely Harsh Environments
    Sensors are key elements for capturing environmental properties and are today indispensable in the industry for monitoring and control of industrial processes. Many applications are demanding for highly integrated intelligent sensors to meet the requirements on safety, clean, and energy-efficient operation, or to gain process information in the context of industry 4.0. While in many everyday objects highly integrated sensor systems are already state of the art, the situation in an industrial environment is clearly different. Frequently, the use of sensor systems is impossible due to the fact that the extreme ambient conditions of industrial processes like high operating temperatures or strong mechanical loads do not allow a reliable operation of sensitive electronic components. Eight Fraunhofer Institutes have bundled their competencies and have run the Fraunhofer Lighthouse Project “eHarsh” to overcome this situation. The project goal was to realize sensor systems for extremely harsh environments, whereby sensor systems are more than pure sensors, rather these are containing one or multiple sensing elements and integrated readout electronics. Various technologies, which are necessary for the realization of such sensor systems, have been identified, developed, and finally bundled in a technology platform. These technologies are, e.g., MEMS and ceramic-based sensors, SOI-CMOS-based integrated electronics, board assembly and laser-based joining technologies. All these developments have been accompanied by comprehensive tests, material characterization, and reliability simulations. Based on the platform, a pressure sensor for turbine applications has been realized to prove the performance of the eHarsh technology platform.
  • Publication
    Smart sensor systems for extremely harsh environments
    Sensors systems are key elements for capturing environmental properties and are increasingly important in industry 4.0 for the intelligent control of processes. However, under harsh operating conditions like high temperatures, high mechanic load or aggressive environments, standard electronics cannot be used. Eight Fraunhofer institutes have therefore bundled their competencies in sensors, microelectronics, assembly, board design, laser applications and reliability analysis to establish a technology platform for sensor systems working under extreme conditions.
  • Publication
    Generative Machine Learning for Resource-Aware 5G and IoT Systems
    Extrapolations predict that the sheer number of Internet-of-Things (IoT) devices will exceed 40 billion in the next five years. Hand-crafting specialized energy models and monitoring sub-systems for each type of device is error prone, costly, and sometimes infeasible. In order to detect abnormal or faulty behavior as well as inefficient resource usage autonomously, it is of tremendous importance to endow upcoming IoT and 5G devices with sufficient intelligence to deduce an energy model from their own resource usage data. Such models can in-turn be applied to predict upcoming resource consumption and to detect system behavior that deviates from normal states. To this end, we investigate a special class of undirected probabilistic graphical model, the so-called integer Markov random fields (IntMRF). On the one hand, this model learns a full generative probability distribution over all possible states of the system-allowing us to predict system states and to measure the probability of observed states. On the other hand, IntMRFs are themselves designed to consume as less resources as possible-e.g., faithful modelling of systems with an exponentially large number of states, by using only 8-bit unsigned integer arithmetic and less than 16KB memory. We explain how IntMRFs can be applied to model the resource consumption and the system behavior of an IoT device and a 5G core network component, both under various workloads. Our results suggest, that the machine learning model can represent important characteristics of our two test systems and deliver reasonable predictions of the power consumption.
  • Publication