Functionalization of UV-curing adhesives for surface-integrated micro-polymer optical fibers

Polymer optical waveguides, especially single-mode waveguides are increasingly used for short distance communication, as well as for sensing applications. The realization of a working communication route requires different and sequentially realized steps. Generally, these steps are the packaging of semiconductor beam senders and receivers, the fabrication of an optical waveguide, the preparation of its end-facets, the alignment of different elements along their optical axis and the integration into a desired communication route. The development of a process, which integrates all these steps for planar surfaces, offers a reduction in time and an increase in flexibility. A sub-step toward such a highly automated system is the integration of optical waveguides into the planar surface. In this context, we are investigating the use of the micro-dispensing process to realize this integration step. We functionalize UV-curing adhesives as cladding for micro-optical cores as well as for inherent bonding to the substrate surface. For this purpose an optical characterization of the adhesives is necessary for an adequate core and cladding material combination. A ow behavior characterization is also relevant in order to analyze the used dispensing process with the selected adhesive. Finally, a mechanical characterization is done to test the adhesion of the core to the adhesive, as well as the adhesive to the substrate surface. In this paper we present a summary of the realized characterization of the selected polymer. Based on experiment results we infer limits and opportunities of this method. © 2016 SPIE.DFG/SFB/65

Position Tracking for Passive UHF RFID Tags with the Aid of a Scanned Array

Thanks to the proliferation of radio frequency identification systems (RFID), applications have emerged concerning positioning techniques for inexpensive passive RFID tags. The most accurate approaches for tracking the tag's position, deliver precision in the order of 20 cm over a range of a few meters and require moving parts in a predefined pattern (mechanical antenna steering), which limits their application. Herein, we introduce an RFID tag positioning system that utilizes an active electronically-steered array, based on the principles of modern radar systems. We thoroughly examine and present the main attributes of the system with the aid of an finite element method simulation model and investigate the system performance with far-field tests. The demonstrated positioning precision of 1.5, which translates to under 1 cm laterally for a range of a few meters can be helpful in applications like mobile robot localization and the automated handling of packaged goods.DF

Low Temperature Optodic Bonding for Integration of Micro Optoelectronic Components in Polymer Optronic Systems

AbstractLarge area, planar optronic systems based on flexible polymer substrates allow a reel-to-reel mass production, which is widely adopted in modern manufacturing. Polymer optronic systems are fully integrated with micro optical and optoelectronic components as light sources, detectors and sensors to establish highly functional sensor networks. To achieve economical production, low-cost polymer sheets are employed. Since they are mostly thermally sensitive, this requires a restricted thermal loading during processing. Furthermore, a short process time improves production efficiency, which plays a key role in manufacturing processes. Thus, in this contribution we introduce a new bare chip bonding technique using light instead of heat to meet both requirements. The technique is based on the conventional flip-chip die bonding process. Ultraviolet radiation curing adhesives are applied as bonding material, accordingly a sideway ultraviolet radiation source, a so-called optode, is designed. Before implementing the concept, the light distribution in the contact spot is simulated to examine the feasibility of the solution. Besides, we investigate two different UV lamps regarding induced thermal influence on polymer substrate to choose one to be employed in the optode. Process factors, irradiation intensity and irradiation time are studied. Based on these results, the mechanical and electrical reliability of the integrated components is finally evaluated

Laser sintering of copper conductive traces on primer pre-treated additive manufactured 3D surfaces

This paper introduces a novel process for creating conductive copper traces on 3D surfaces from different additive manufacturing technologies by employing printed electronics techniques. An essential step in this process was the dip-coating pre-treatment with a primer to reduce the surface roughness below 100 nm, seal pores if present, and increase the thermal stability. This was followed by a dip-coating with copper nanoparticle ink, drying using a heat gun and thermal curing by laser sintering. The experiments determined the optimal laser peak intensity for achieving conductors with the lowest electrical resistance possible. The laser parameters' processing window provided conductive traces on 3D surfaces with properties comparable to photonic sintering on planar substrates. Thereby, the conductive traces reached electrical specific resistances lower than 18 µΩ cm (elemental copper: ρ = 1.8 µΩ cm) and a copper material percentage higher than 90 atom %. Shear tests validated the assembly with surfacemount device (SMD) resistors. Electrical tests resulted in maximum current densities higher than 100 A mm-2 and lateral breakdown voltages higher than 2kV mm-1. Thus, this paper presents essential prerequisites for a future application of the technology

IASAS Student Leader Global Summit 2019

Leadership and mental health came under the spotlight when more than 50 student leaders from all over the world met at Stellenbosch University (SU) from 23 to 26 June 2019 for the International Association of Student Affairs and Services (IASAS) Student Leader Global Summit. It was the first time that SU hosted this global summit for student leaders.  IASAS is a nonprofit organisation that was founded in Belgium in 2013. It is a worldwide association of university professionals working in the area of student affairsand services. IASAS has more than 1 400 individual, institutional and association members representing over 90 countries on five continents.The fourth IASAS Student Leader Global Summit (SLGS) welcomed 45 students from 14 countries across the world. The SLGS provides a global platform for improving multi- and intercultural communication and understanding amongst students. The goal of the summits is to bring student leaders from different parts of the world together to discuss student governance, leadership, social justice and other topics of shared interest

Optical autonomous sensor module communicating with a smartphone using its camera

Wireless optical communication is a viable alternative to conventional RF technology. Our novel design combines optical communication and energy harvesting in one device with a size of 30 x 10 x 5 mm using the latest innovations in lowpower electronics and solar cell technology. In our study, we implement visible light communication between a sensor module and a smartphone. The proposed system design and a communication protocol are specifically developed for environments with illumination levels of 100-500 lux, like industrial halls. The sensor integrated into the module can vary according to application requirements. As an example, in our work, we use a temperature and pressure sensor and an accelerometer. A bright flash from a smartphones build-in LED activates the module. The module takes measurements and sends the result in form of an optical data signal, which is then received by the smartphone camera. This technique is able to provide reliable communication despite low-power restrictions of energy harvesting. By using a smartphone this approach offers more convenience to a user and enables flexible deployment of the modules in industrial machinery. © 2019 SPIE

Semi-automated method for reviewing 3d printing datasets

There are many datasets available for various applications. Datasets, however, that consist of production data (such as Computer Aided Design, CAD) are scarce. There is no dataset that provides data for the whole process from engineering to production. Usually, production process data as well as design specifics are well kept secrets and may decide a company’s success. With the wide spread of additive manufacturing machines such as fused deposition modeling (FDM) machines (3d printers), additive manufacturing has become broadly available. With additive manufacturing it is possible to manufacture arbitrary objects with machines that share a common toolset. Thus, the goal of our research was to create a homogeneous 3d dataset that not only consists of the original 3d models, but also of the resulting production files (G-Codes). To achieve this, we reviewed 12 different 3d datasets and examined a small-sized sample in respect of its suitability for 3d printing. We then developed a tool for semi-automated reviewing and editing of the dataset. After reviewing and editing the 3d dataset, production data was generated via slicing software

Methuosis Nonapoptotic Cell Death Associated with Vacuolization of Macropinosome and Endosome Compartments

Apoptosis is the most widely recognized form of physiological programmed cell death. During the past three decades, various nonapoptotic forms of cell death have gained increasing attention, largely because of their potential importance in pathological processes, toxicology, and cancer therapy. A recent addition to the panoply of cell death phenotypes is methuosis. The neologism is derived from the Greek methuo (to drink to intoxication) because the hallmark of this form of cell death is displacement of the cytoplasm by large fluid-filled vacuoles derived from macropinosomes. The demise of the cell resembles many forms of necrosis, insofar as there is a loss of metabolic capacity and plasma membrane integrity, without the cell shrinkage and nuclear fragmentation associated with apoptosis. Methuosis was initially defined in glioblastoma cells after ectopic expression of activated Ras, but recent reports have described small molecules that can induce the features of methuosis in a broad spectrum of cancer cells, including those that are resistant to conventional apoptosis-inducing drugs. This review summarizes the available information about the distinguishing morphological characteristics and underlying mechanisms of methuosis. We compare and contrast methuosis with other cytopathological conditions in which accumulation of clear cytoplasmic vacuoles is a prominent feature. Finally, we highlight key questions that need to be answered to determine whether methuosis truly represents a unique form of regulated cell death

Additive manufacturing of copper vertical interconnect accesses by laser processing

This paper introduces a new manufacturing process for vertical interconnect accesses (VIA). In contrast to industrially established VIA metallization technologies, the presented approach takes place without any chemical plating by combining copper ink and epoxy insulator coating with CO2 laser processing for VIA drilling and copper ink sintering. The minimum VIA resistances are less than 50 mΩ, fitting the theoretically calculated value. A laboratory application scenario testing a 10 × 10 contact pad array with a pitch of 800 µm successfully demonstrates routing across five printed metallization layers, including 128 blind and 112 buried VIA. © 2021 The Author