Bladder tumor recurrence is a serious problem in uro-oncology, as it increases the risk of fatal progression and makes further surgeries necessary. The possibility of intraoperative tissue differentiation can help for diagnostic purposes as well as for ensuring that the entirety of the tumor is removed. The latter not only differ visually from healthy tissue, but also in their mechanical and electrical properties due to an altered physiology. A possible base for intraoperative tissue differentiation are impedance measurements, which are, however, difficult to obtain passing through the limited space of the urethra. This work presents a comparative study of two impedance sensors, which are obtained by laser direct structuring and rely on a four terminal measurement. The miniaturized sensors are suitable for minimally invasive usage. Circular electrodes are placed in a square for a first sensor, whereas a novel combination of one circular electrode and three concentric rings is designed for the second sensor. For each sensor, the specific geometry factor is determined and the impact of sensitivity towards small conductivity changes inside the tissue investigated. Furthermore, multiple ex vivo measurements on fresh pig bladders are carried out with each sensor. It is shown that both sensors reliably determine tissue impedance data that fit empirical tissue models. Conductivity values close to listed data of human urinary bladder are obtained. Ultimately, the novel ring sensor configuration turns out more favorable in terms of sensitivity distribution and yields more reproducible results than the square electrode arrangement.

High quality and long product life are two fundamental requirements for all circuit carriers, including molded interconnect devices (MID), to find application in various fields, such as automotive, sensor technology, medical technology, and communication technology. When developing a MID for a certain application, not only the design, but also the choice of material as well as the process parameters need to be carefully considered. A well-established method to evaluate the lifetime of such MID, respective of their conductor tracks, is the thermal shock test, which induces thermomechanical stresses upon cycling. Even though this method has numerous advantages, one major disadvantage is its long testing time, which impedes rapid developments. Addressing this disadvantage, this study focuses on the laser direct structuring of thermoplastic LCP Vectra E840i LDS substrates and the subsequent electroless metallization of the commonly used layer system Cu/Ni/Au to force differences in the conductor tracks’ structure and composition. Performing standardized thermal shock tests alongside with flexural fatigue tests, using a customized setup, allows comparison of both methods. Moreover, corresponding thermomechanical simulations provide a direct correlation. The flexural fatigue tests induce equivalent or even higher mechanical stresses at a much higher cycling rate, thus drastically shorten the testing time.

Circuit carriers perform various functions within electrical systems and products. This includes being the assembly platform for various components. To mount these components, soldering processes are predominantly used because of economic and technical benefits compared to other assembly technologies. Therefore, novel circuit carrier technologies should be compatible with soldering processes to compete with the state of the art. One of these innovative circuit carrier technologies is based on anodized aluminum substrates, which are characterized by their low cost and low thermal resistance. In this article, circuit carriers made of anodized aluminum with two different oxide morphologies being investigated. In addition, three different metallization processes were compared with regard to their suitability for a reflow soldering process for the assembly of surface mount devices (SMDs). In order to evaluate the assemblies, the force required to shear off the SMDs was measured before and after a cyclic thermal shock test (TST). One of the three investigated metallization processes yielded circuit carriers based on anodic aluminum oxide that enabled reflow soldering of the given SMD components. It was determined that both, the layer morphology and the metallization process, had an influence on the measured shear forces before and after TST.