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

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

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

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

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

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

Optical coupling of bare optoelectronic components and flexographically printed polymer waveguides in planar optronic systems

Large scale, planar optronic systems allowing spatially distributed functionalities can be well used in diverse sensor networks, such as for monitoring the environment by measuring various physical quantities in medicine or aeronautics. In these systems, mechanically flexible and optically transparent polymeric foils, e.g. polymethyl methacrylate (PMMA) and polyethylene terephthalate (PET), are employed as carrier materials. A benefit of using these materials is their low cost. The optical interconnections from light sources to light transmission structures in planar optronic systems occupy a pivotal position for the sensing functions. As light sources, we employ the optoelectronic components, such as edgeemitting laser diodes, in form of bare chips, since their extremely small structures facilitate a high integration compactness and ensure sufficient system flexibility. Flexographically printed polymer optical waveguides are deployed as light guiding structures for short-distance communication in planar optronic systems. Printing processes are utilized for this generation of waveguides to achieve a cost-efficient large scale and high-throughput production. In order to attain a high-functional optronic system for sensing applications, one of the most essential prerequisites is the high coupling efficiency between the light sources and the waveguides. Therefore, in this work, we focus on the multimode polymer waveguide with a parabolic cross-section and investigate its optical coupling with the bare laser diode. We establish the geometrical model of the alignment based on the previous works on the optodic bonding of bare laser diodes and the fabrication process of polymer waveguides with consideration of various parameters, such as the beam profile of the laser diode, the employed polymer properties of the waveguides as well as the carrier substrates etc. Accordingly, the optical coupling of the bare laser diodes and the polymer waveguides was simulated. Additionally, we demonstrate optical links by adopting the aforementioned processes used for defining the simulation. We verify the feasibility of the developed processes for planar optronic systems by using an active alignment and conduct discussions for further improvements of optical alignment. © 2016 SPIE.DFG/CRC/TR 12

Investigation on Aging of Metallic Surface Integrated Micro-POFs

Surface integrated optical waveguides present a possibility to realize inherent communication structures. Optical communication is used particularly by smart parts exposed to humidity, high vibration or electromagnetic fields. We developed a method to integrate micro-polymer optical fibers ( μ -POFs) into metallic surfaces using the dispensing process. After positioning, the μ -POFs are bonded to the surface by dispensing UV-curing adhesives. The bonded optical waveguide is coupled at its end-facets respectively to sender or receiver elements. Efficiency of the coupling depends on the alignment stability of the polymer fiber to beam sender or receiver. In operating conditions the smart parts undergo aging due to thermal and mechanical stress. We investigated the possible influence of this aging on the position stability of bonded μ -POFs, and consequently on the optical communication efficiency. The experimental set-up as well as the measurements are presented and discussed in this article