Volume 84, Issue 1 - IEEE Workshop/SENSORICA 2016 in Mülheim an der Ruhr / Jörg Himmel, Olfa Kanoun, Thomas Seeger, Klaus Thelen

A single coil element based on a composite right/left-handed (CRLH) metamaterial transmission line for combined sodium and hydrogen MRI is presented. It provides the particular feature of equal quarter-wavelength current and electromagnetic (EM) field distributions at the two distinct Larmor frequencies of 23 Na- and 1 H-nuclei at 7 T magnetic flux density. The functionality of a manufactured prototype is validated through near-field measurements that are compared with finite-difference time-domain (FDTD) simulations. Finally, results of a first successful MRI experiment are presented for a canister phantom including ping-pong ball insets filled with different liquids of high sodium concentrations.

Emissions of internal combustion engines are linked to air pollution, global warming effects and are potentially harmful. In order to reduce emissions, a better understanding of combustion processes is necessary. Therefore, the combustion temperature is an important factor to know, because it has an impact on the amount of exhaust gases like soot and nitrogen oxides. This work presents a complete spectral resolved emission spectroscopy based sensor system for temperature determining in compression ignition engines. The sensor system is developed for series engines and can be used without any modification of the engine.

Laser-induced breakdown spectroscopy (LIBS) with pulsed laser excitation is a well-established method for analyzing the atomic components of an unknown sample based on their characteristic emission spectra. However, standard LIBS analysis provides insufficient results if the atoms to be measured exhibit weak elemental emission lines or if characteristic elemental spectra are disturbed by overlapping stronger lines of other elements in the sample. The analysis of the molecular emission bands arising in the plasma cooling phase seems to be a promising solution. The analysis is carried out by the observation of newly formed radicals and diatomic molecules whose strong molecular emission bands can often be found in the visible spectral region and offer a higher detection sensitivity. This generally requires a time resolved measurement of the LIBS spectra, but we show that in some cases this is not necessarily needed. As an application we present the measurement of chloride contamination in concrete that could help to estimate the repair demand of infrastructure buildings in future.

In the past two decades, ionic liquids have found many applications as solvents for complex solutes. Prominent examples are the dissolution of biomass and carbohydrates as well as catalytically active substances. The chemical analysis of such solutions, however, is still a challenge due to the molecular complexity. In the present work, the use of infrared spectroscopy for quantifying the concentration of different solutes dissolved in an imidazolium-based ionic liquid is investigated. Binary solutions of glucose, cellubiose, and Wilkinson's catalyst in 1-ethyl-3-methylimidazolium acetate are studied as examples. For this purpose, different chemometric approaches (principal component analysis (PCA), partial least-squares regression (PLSR), and principal component regression (PCR)) for analyzing the spectra are tested. Principal component analysis was found to be suitable for classifying the different solutions. Both regression techniques were capable of deriving accurate concentration values. The performance of PLSR was slightly better than that of PCR for the same number of components.

This article presents common methods for calculating the scaling factor in X-ray images and reveals their basic technical difficulties, accuracy and error sources. Further, the causes for magnification of patient anatomy in X-ray images are described. Preoperative planning by means of X-ray images, its difficulties, reliability and limitations are also illustrated. Additionally, a new approach is introduced which is based on a stereo camera system used to identify the magnification especially in anterior-posterior pelvis images for hip application, considering the geometry of X-ray apparatus while minimizing errors by foreclosing the well-known central issues of all the conventional methods for the most part.

The use of new soft robots in minimally invasive surgery offers exciting new possibilities while it generates new challenges for the technical implementation. In this article, two methods for the detection of a soft flexible robot arm are presented. Based on the image information of an endoscopic camera, the visible sections are evaluated to determine the position of the robot. Both methods have been integrated and tested in the newly developed system.

Long-term monitoring of hemodynamics can be achieved by an implantable and telemetric multi-sensor system. A concept to realize a system with high miniaturization level is presented. The requirements regarding a multifunctional transponder ASIC (application specific integrated circuit), which should combine signal processing, telemetric communication and additional sensors in one chip, are introduced. Capacitive pressure sensors showing low power consumption were tested with laboratory setups with respect to the integration in this concept. First results were achieved and discussed concerning two potential assembly technologies for the integration of a pressure sensor. Finally, hermetic sealing and implant encapsulation technologies are proposed for further implant miniaturization.

In order to analyze the beam quality of laser sources wavefront measurements using a Shack–Hartmann sensor became an established way. With the detection of the wavefront deflection a change of the modal composition of the laser beam can be recorded directly. While this method is well known for nearly Gaussian laser beams, the wavefront analysis of broadarea semiconductor lasers is an open field of current research. Detailed analysis of the wavefront gives an additional path to get an insight into the transverse modal composition of semiconductor lasers, which have a dominant impact on the output parameters of the devices. For the presented investigations lasers emitting light in the near infrared ( λ  = 830/980 nm) based on the material system GaAs are utilized. For this type of laser the number and structure of optical modes is affected by thermal as well as electric effects inside the active medium. It is shown that the detected wavefront can be associated with a composition of Legendre polynomials. Additionally the transformation of these polynomials is examined under changing working conditions of the laser.