Michael Thomaschewski

Barium titanate (BTO), one of the earliest reported ferroelectric materials, exhibits strong second-order nonlinearity and an ultrafast Pockels effect, making it highly attractive for photonics. However, its optical constants remain uncertain largely due to the ubiquitous ferroelectric–ferroelastic multidomain microstructure, which depolarizes and averages out the anisotropic optical response, thereby complicating conventional ellipsometric approaches. Here, we report a Kramers–Kronig-consistent complex refractive-index tensor of tetragonal BTO from the ultraviolet (190 nm) to the far-infrared (40 μm) derived from multimodal Mueller-matrix spectroscopic ellipsometry. We further quantify optical loss by incorporating transmission intensity measured over the 2–10 μm transparency window, resolving the extinction coefficient down to ∼10–5. To verify the underlying domain configuration, we performed independent structural analyses, including electron backscatter diffraction, confocal Raman microscopy, and Kelvin probe force microscopy. We then reconstruct an effective optical model for our multidomain BTO sample, formulated as a mixture of three tetragonal variants with the determined intrinsic refractive indices, to link microscopic domains to the macroscopic optical response. Our work presents a unified, experimentally cross-validated data set, enabling accurate modeling for electro-optic modulators and high-Q nanophotonic resonators without ad hoc approximations, and provides a general strategy for optical metrology of complex ferroic crystals.

Zusammenfassung: Der digitale Zwilling (Digital Twin) bezeichnet die virtuelle, dynamische Repräsentation eines realen Objektes, die durch kontinuierlichen Datenaustausch mit ihrem physischen realen Objekt aktualisiert wird. Ursprünglich in industriellen Anwendungsfeldern etabliert, gewinnt das Konzept zunehmend auch in der Medizin und hierbei vor allem in der Chirurgie an Bedeutung. Digitale Zwillinge integrieren multimodale Patientendaten, darunter Bilddaten, physiologische Messwerte und intraoperative Sensordaten, zu patientenspezifischen Modellen. Diese können in der präoperativen Planung, intraoperativen Entscheidungsunterstützung sowie in der postoperativen Verlaufskontrolle eingesetzt werden. Erste Anwendungen, insbesondere in der onkologischen und vaskulären Chirurgie, zeigen ein hohes Potenzial zur Verbesserung der chirurgischen Präzision und zur Reduktion von Komplikationen. Darüber hinaus eröffnen digitale Zwillinge neue Möglichkeiten in der chirurgischen Ausbildung und Telechirurgie. Trotz vielversprechender Ansätze befinden sich digitale Zwillinge in der Chirurgie noch überwiegend in frühen Entwicklungsstadien. Herausforderungen bestehen insbesondere in der Datenqualität, Modellvalidierung sowie in ethischen und rechtlichen Fragestellungen. Insgesamt besitzen digitale Zwillinge das Potenzial, die chirurgische Behandlung nachhaltig zu verändern.

Minimally invasive stabilization of acetabular and pelvic ring fractures using endoscopic techniques has become increasingly important. The logical advance

We report a scalable approach for fabricating single-crystal barium titanate (BTO) thin films through spalling from bulk substrates. Conventional thin film growth techniques often face challenges in achieving high-quality single crystal microstructure over large areas, resulting in reduced performance in functional devices. In contrast, spalling, i.e., performing stress-induced exfoliation of bulk single crystals, enables the separation of single crystal thin films with controllable thicknesses ranging from 100 nm to 15 μm and lateral dimensions up to several millimeters. Electro-optic characterization of the spalled films yields a Pockels coefficient of r₃₃ = 55 pm/V in multidomain regions and 160 pm/V in single-domain regions, leading to projections up to 1980 pm/V for r₄₂ under conditions of unclamped excitation. Our results indicate that spalled BTO single-crystal thin films preserve bulk electro-optic properties and exceed the performance of commercially available thin film lithium niobate, making them suitable for integration in advanced photonic and optoelectronic devices.

Arrays of photodetector‐based pixel sensors are ubiquitous in modern devices, such as smart phone cameras, automobiles, drones, laptops etc. Two‐dimensional (2D) material‐based photodetector arrays are a relevant candidate, especially for applications demanding planar form factors. However, shortcomings in pixel density and prototyping without cross contamination limit technology adoption and impact. Also, while 2D material detectors offer high absorption, graphene's closed bandgap results in undesirably high dark currents. Here, we introduce the experimental demonstration of dense planar photodetector arrays. We demonstrate a micrometer‐narrow pitched 2D detector pixels and show this approach's repeatability by verifying performing of a 16‐pixel detector array. Such dense and repeatable detector realization is enabled by a novel, selective, contamination‐free 2D material transfer system, that we report here in automated operation. The so realized photodetectors responsivity peaks at a high 0.8 A/W. Furthermore, we achieve uniform detector performance via bias voltage tuning calibration to maximize deployment. Lastly, we demonstrate 2D arrayed photodetectors not only on a silicon chip platform but verify array performance on flexible polymer substrates. Densley‐arrayed, flat, bendable, and uniform performing photodetector pixels enable emerging technologies in the space where lightweight and reliable performance is required, such as for the smart phone and emerging VR/AR markets, but also for smart gadgets, wearables, and also for size‐weight‐power‐constrained aviation and space platforms.

Zusammenfassung: Seit dem Jahr 2023 wird das Hugo Robotic-Assisted Surgery System in der Allgemein- und Viszeralchirurgie angewendet. Das Hugo Robotic-Assisted Surgery System verspricht, durch seine Modularität, Flexibilität und mit dem offenen Konsolendesign die robotische Chirurgie weiter zu verbessern. Aufgrund der Neuheit des Systems gibt es derzeit aber nur wenige Erfahrungen in der klinischen Anwendung. Bei dem vorliegenden klinischen Bericht handelt es sich um einen Patienten mit einem Adenokarzinom des gastroösophagealen Überganges (AEG) Siewert Typ 2. Das Staging ergab folgendes Tumorstadium: uT3 uN1 cM0. Nach einer neoadjuvanten Chemotherapie (4 Zyklen FLOT) erfolgte die Indikationsstellung zur onkologischen Resektion. Aufgrund der reduzierten Lungenfunktion wurde der Patient für eine transhiatal erweiterte Ösophagusresektion vorgesehen. Die Operation erfolgte mit dem Hugo Robotic-Assisted Surgery System mit 4 Roboterarmen und 2 Assistententrokaren. Die Operationszeit betrug insgesamt 240 min. Im abschließenden histopathologischen Befund des Resektionspräparates konnte eine R0-Resektion bestätigt werden. Die Resektion erfolgte robotisch assistiert, während die Rekonstruktion (Double-Tract-Rekonstruktion) durch eine Minilaparotomie erfolgte. Der hier dargestellte klinische Fall berichtet erstmals von der Durchführung einer distalen transhiatalen Ösophagusresektion mit dem Hugo Robotic-Assisted Surgery System bei einem Patienten mit einem AEG Siewert Typ 2.

Background: Learning basic laparoscopic skills can be efficiently performed ex vivo in a safe environment using simulation devices. However, in many countries, the broad and mandatory implementation of ex vivo laparoscopic simulation training in surgical residency is still lacking. The aim of the study was to evaluate the efficacy of laparoscopic basic skills simulation training on the surgical performance of residents during their first laparoscopic procedures in the operating room. Methods: This was a multicenter, prospective, randomized, two-arm, single-blind trial. The study recruited first-year surgical residents (NOVICE) with no previous personal experience in laparoscopic surgery. After the participants had performed their first laparoscopic cholecystectomy, they were randomized into two groups: the intervention group underwent six weeks of standardized laparoscopic basic skills simulation training (Lübeck Toolbox Curriculum), whereas the control group did not. After six weeks, both groups performed a second cholecystectomy. The videotapes of the first and second cholecystectomies were evaluated blinded based on the Global Operative Assessment of Laparoscopic Skill (GOALS) score. The primary endpoint was the changes in the GOALS scores between the first and second cholecystectomies. Results: 22 surgical residents from 11 surgical clinics in Germany were included, and 4 residents dropped out. The median improvement in the LTB-Curriculum group between CHE I and CHE II was 8.5 GOALS score points in contrast to 2 points in the control group. This difference was statistically significant (95%CI: 1–15 points, P = 0.013). Conclusion: Ex-vivo training in basic laparoscopic skills significantly improved the surgical performance of residents during their first laparoscopic cholecystectomies in the operating room.