Effects of grain shape on packing and dilatancy of sheared granular materials

Granular material exposed to shear shows a variety of unique phenomena: Reynolds dilatancy, positional order and orientational order effects may compete in the shear zone. We study granular packings consisting of macroscopic prolate, oblate and spherical grains and compare their behaviour. X-ray tomography is used to determine the particle positions and orientations in a cylindrical split bottom shear cell. Packing densities and the arrangements of individual particles in the shear zone are evaluated. For anisometric particles, we observe the competition of two opposite effects. One the one hand, the sheared granulate is dilated, but on the other hand the particles reorient and align with respect to the streamlines. Even though aligned cylinders in principle may achieve higher packing densities, this alignment compensates for the effect of dilatancy only partially. The complex rearrangements lead to a depression of the surface above the well oriented region while neigbouring parts still show the effect of dilation in the form of heaps. For grains with isotropic shapes, the surface remains rather flat. Perfect monodisperse spheres crystallize in the shear zone, whereby positional order partially overcompensates dilatancy effects. However, already slight deviations from the ideal monodisperse sphere shape inhibit crystallization.Comment: 12 pages, 13 figures, accepted in Soft Matte

Nutzerintegration bei der Produktentwicklung am Beispiel der Medizintechnik

Aus der Einführung: "Eine systematische Vorgehensweise entsprechend der Konstruktionsmethodik gilt als zielführender Ansatz bei der Findung von technischen Lösungen und der Entwicklung von Produkten. In der Literatur finden sich dazu zahlreiche Veröffentlichungen z. B. Feldhusen & Grote 2013; Ehrlenspiel 2014; Ehrlenspiel 2009; Roth 1994 und Livotov 2013. Die VDI Richtlinie 2221 „Methodik zum Entwickeln und Konstruieren technischer Systeme und Produkte“ (VDI 1993) beschreibt ebenfalls allgemeingültige Regeln bei der systematischen Lösungsfindung. Iterativ wird in mehreren Teilschritten eine zuvor definierte Aufgabe in eine Lösung überführt. Dabei werden die Phasen der Planung, der Konzeption, des Entwurfes und der Ausarbeitung durchschritten. In der Literatur und den Richtlinien ist jedoch keine explizite Rückkopplung mit dem Nutzer gefordert oder angedacht. Gerade vor dem Hintergrund der voranschreitenden Individualisierung der Produkte und kann hierin ein entscheidender Vorteil liegen. Entwicklungszyklen und die Zeit bis zur Markteinführung von Produkten können reduziert werden. Zudem ist von einer höheren Akzeptanz durch den Kunden auszugehen. ...

In-room ultrasound fusion combined with fully compatible 3D-printed holding arm - rethinking interventional MRI

There is no real need to discuss the potential advantages - mainly the excellent soft tissue contrast, nonionizing radiation, flow, and molecular information - of magnetic resonance imaging (MRI) as an intraoperative diagnosis and therapy system particularly for neurological applications and oncological therapies. Difficult patient access in conventional horizontal-field superconductive magnets, very high investment and operational expenses, and the need for special nonferromagnetic therapy tools have however prevented the widespread use of MRI as imaging and guidance tool for therapy purposes. The interventional use of MRI systems follows for the last 20+ years the strategy to use standard diagnostic systems and add more or less complicated and expensive components (eg, MRI-compatible robotic systems, specially shielded in-room monitors, dedicated tools and devices made from low-susceptibility materials, etc) to overcome the difficulties in the therapy process. We are proposing to rethink that approach using an in-room portable ultrasound (US) system that can be safely operated till 1 m away from the opening of a 3T imaging system. The live US images can be tracked using an optical inside-out approach adding a camera to the US probe in combination with optical reference markers to allow direct fusion with the MRI images inside the MRI suite. This leads to a comfortable US-guided intervention and excellent patient access directly on the MRI patient bed. This was combined with an entirely mechanical MRI-compatible 7 degrees of freedom holding arm concept, which shows that this test environment is a different way to create a cost-efficient and effective setup that combines the advantages of MRI and US by largely avoiding the drawbacks of current interventional MRI concepts

Endoscopic Imaging Technology Today

One of the most applied imaging methods in medicine is endoscopy. A highly specialized image modality has been developed since the first modern endoscope, the “Lichtleiter” of Bozzini was introduced in the early 19th century. Multiple medical disciplines use endoscopy for diagnostics or to visualize and support therapeutic procedures. Therefore, the shapes, functionalities, handling concepts, and the integrated and surrounding technology of endoscopic systems were adapted to meet these dedicated medical application requirements. This survey gives an overview of modern endoscopic technology’s state of the art. Therefore, the portfolio of several manufacturers with commercially available products on the market was screened and summarized. Additionally, some trends for upcoming developments were collected

Is a thin diameter ureteroscope feasible for image guided intravascular procedures?

Vascular endoscopic imaging is known for a long time but has never made its way into clinical routine. Reasons for that are the complexity, lack of low-cost portable systems, and the lack of suitable endoscopes providing high image quality with small dimensions. In addition, an interruption of the blood flow caused by the device and the opacity of blood are difficult to manage. In the past we have already developed ideas to overcome these difficulties and now we present a feasibility test of a thin diameter ureteroscope for observation of vascular procedures. The imaging system was tested in a phantom where side branches were explored, a stent was placed and a simulated aneurysm coiled

How do we need to adapt Biomedical Engineering Education for the Health 4.0 challenges?

Novel challenges and developments require adaptations on skill set, content, and associated education. A biomedical engineer will require a broad range of skills - which to a large extent are currently not taught - in the coming years to meet the development needs of future healthcare: intensive interdisciplinary team work, advanced communication skills, team management and coaching capabilities, advanced project management, learn how to learn, visionary and forward looking thinking, understanding of health economics, entrepreneurship and leadership. But above all empathy towards the clinical user and patients is needed as well as a basic understanding of the current and future clinical workflows that can globally vary. An innovation process for a healthcare related product or service will likely only create value through the consideration and implementation of several of these points. Even though techniques for the development of innovation and enhancing creativity in individuals are widely discussed, there are relatively few reports on the practice of mainstreaming creativity in an organizational setting. We report on the setup of our Graduate School “Technology Innovation in Therapy and Imaging (T²I²)” that has implemented a structured post graduate program and focuses on interdisciplinary and application-oriented innovation generation education. The educational process starts with the observation and identification of clinical needs and an in-depth understanding of the problem and subsequently covers all steps necessary to transfer prototypes into viable solutions and further into implementing valuable products

Novel flexible endoscope concept with swiveling camera tip

Endoscopy is an important modality in medical imaging. Thin flexible endoscopes are for example used to examine the upper airways, for gastroscopy procedures or lung inspection. With standard flexible endoscopes one can change the direction of view by bending the tip with the disadvantage of large space required due to the bending radius. With first experiences of a concept of a moveable camera head on the tip of rigid endoscopes, we now propose a novel design employing a swiveling camera for flexible endoscopes. This concept is based on the use of a shape memory wire used to control the movement of the camera, a flexible plastic flap joint for tight rotation and flexible printed circuits for the electronic connection. The prototype was realized in a first low cost setup using a 5,5 mm HD chip on the tip camera with LED light. The motion and imaging performance of the prototype allowed swiveling of the camera on the endoscope tip from straight view to 100° side view. The space needed in fully rotation was limited to 9mm with an overall diameter of the endoscope in straight view of only 5,6mm, but could even be further reduced in a more professional setup. The image quality is good, but close-up views appear blurry due to the fixed focus point of the low-cost camera. The presented steering concept of the camera is promising, as it could potentially improve imaging of narrow cavities using flexible endoscopes. Especially for “in office” examinations this principle could add value to diagnosis and patient comfort

INNOLAB- image guided surgery and therapy lab

Incremental innovation, something better or cheaper or more effective, is the standard innovation process for medical product development. Disruptive innovation is often not recognized as disruptive, because it very often starts as a simple and easy alternative to existing products with much reduced features and bad performance. Innovation is the invention multiplied with a commercial use, or in other words something that eventually provides a value to a clinical user or patient. To create such innovation not a technology push (technology delivered from a technical need perspective) but rather a pull (by learning and working with the clinical users) is required. Medical technology students need to understand that only through proper observation, procedure know-how and subsequent analysis and evaluation, clinically relevant and affordable innovation can be generated and possibly subsequently used for entrepreneurial ventures. The dedicated laboratory for innovation, research and entrepreneurship- INNOLAB ego.-INKUBATOR IGT (Image Guided Therapies) is financed by the state of Sachsen-Anhalt as part of the European ego.-INKUBATOR program with (EFRE funds) at the university clinic operated by the technical chair for catheter technologies and image guided surgeries. It forms a network node between medicine, research and economics. It teaches students to lead innovation processes, technology transfer to the user and is designed to stimulate the start-up intentions

Interactive monitoring system for visual respiratory biofeedback

In almost any medical procedure respiratory motion is an issue and may result in image degradation. Most currently available devices and systems, which are intended to reduce respiratory influences do not come into operation however in clinics due to their high cost and complex operation. In our paper we evaluated an interactive breath hold control system that helps flat breathing to subsequently reduce respiratory motion during signal acquisitions or procedure treatments. With that the human subjects are enabled to regulate their own breath by following visual feedback via a specially designed display. That display shows biofeedback information about the respiratory excursion through air pressure deviations measured inside an air bellows belt. The system was assessed quantitatively in a laboratory setup and qualitatively by applications in real clinical procedures. The obtained results are very promising and can be further improved with additional developments to provide an easy to use and relatively inexpensive solution for respiratory motion related imaging problems