Incompressible Squeeze-Film Levitation

Transverse vibrations can induce the non-linear compression of a thin film of air to levitate objects, via the squeeze film effect. This phenomenon is well captured by the Reynolds' lubrication theory, however, the same theory fails to describe this levitation when the fluid is incompressible. In this case, the computation predicts no steady-state levitation, contradicting the documented experimental evidence. In this letter, we uncover the main source of the time-averaged pressure asymmetry in the incompressible fluid thin film, leading the levitation phenomenon to exist. Furthermore, we reveal the physical law governing the steady-state levitation height, which we confirm experimentally

Catheter steering in interventional cardiology: Mechanical analysis and novel solution

In recent years, steerable catheters have been developed to combat the effects of the dynamic cardiac environment. Mechanically actuated steerable catheters appear the most in the clinical setting; however, they are bound to a number of mechanical limitations. The aim of this research is to gain insight in these limitations and use this information to develop a new prototype of a catheter with increased steerability. The main limitations in mechanically steerable catheters are identified and analysed, after which requirements and solutions are defined to design a multi-steerable catheter. Finally, a prototype is built and a proof-of-concept test is carried out to analyse the steering functions. The mechanical analysis results in the identification of five limitations: (1) low torsion, (2) shaft shortening, (3) high unpredictable friction, (4) coupled tip-shaft movements, and (5) complex cardiac environment. Solutions are found to each of the limitations and result in the design of a novel multi-steerable catheter with four degrees of freedom. A prototype is developed which allows the dual-segmented tip to be steered over multiple planes and in multiple directions, allowing a range of complex motions including S-shaped curves and circular movements. A detailed analysis of limitations underlying mechanically steerable catheters has led to a new design for a multi-steerable catheter for complex cardiac interventions. The four integrated degrees of freedom provide a high variability of tip directions, and repetition of the bending angle is relatively simple and reliable. The ability to steer inside the heart with a variety of complex shaped curves may potentially change conventional approaches in interventional cardiology towards more patient-specific and lower complexity procedures. Future directions are headed towards further design optimizations and the experimental validation of the prototype

High impact technologies for endovascular treatment of chronic total occlusions

Medical Instruments & Bio-Inspired Technolog

Design of the flexible HORSE morcellator for the surgical treatment of Cushing's disease in horses

Thesis on the design of a flexible morcellator for the surgical treatment of Cushing's disease in horses. Currently there is no surgical treatment possible in horses due to lack of a surgical approach and tools. In this study a new innovative flexible tool is developped in combination with a surgical approach that can be used for the surgical treatment. The prototype was succesfully tested, allowing for surgical treatment of Cushing's disease in horses in the near future.BMEBioMechanical EngineeringMechanical, Maritime and Materials Engineerin

Design of non-assembly mechanisms: A state-of-the-art review

Additive Manufacturing (AM) or 3D printing has enabled the production of increasingly complex parts that are difficult to produce with conventional manufacturing methods. Its additive nature has made it possible to create interlocking parts in a single production step. This creates opportunities for new ways of designing and producing mechanisms, which do not need to be assembled after production, called non-assembly mechanisms. Non-assembly mechanisms are different from traditional mechanisms, since they show an unprecedented integration between geometry, material and structure. In this review, by means of a systematic literature search the current state-of-the-art of non-assembly mechanisms is reviewed and analyzed based on the challenges encountered in their design and production. The found examples were categorized according to types of mechanism that have similar production considerations. Per category is discussed what the challenges and opportunities are for the design of non-assembly mechanisms. This review aims to provide a helpful overview of best-practice examples that can be used as inspiration for further development of innovative non-assembly mechanisms.</p

Design of non-assembly mechanisms: A state-of-the-art review

Additive Manufacturing (AM) or 3D printing has enabled the production of increasingly complex parts that are difficult to produce with conventional manufacturing methods. Its additive nature has made it possible to create interlocking parts in a single production step. This creates opportunities for new ways of designing and producing mechanisms, which do not need to be assembled after production, called non-assembly mechanisms. Non-assembly mechanisms are different from traditional mechanisms, since they show an unprecedented integration between geometry, material and structure. In this review, by means of a systematic literature search the current state-of-the-art of non-assembly mechanisms is reviewed and analyzed based on the challenges encountered in their design and production. The found examples were categorized according to types of mechanism that have similar production considerations. Per category is discussed what the challenges and opportunities are for the design of non-assembly mechanisms. This review aims to provide a helpful overview of best-practice examples that can be used as inspiration for further development of innovative non-assembly mechanisms.Medical Instruments & Bio-Inspired Technolog

A bio-inspired expandable soft suction gripper for minimal invasive surgery—an explorative design study

Gripping slippery and flexible tissues during minimal invasive surgery (MIS) is often challenging using a conventional tissue gripper. A force grip has to compensate for the low friction coefficient between the gripper’s jaws and the tissue surface. This study focuses on the development of a suction gripper. This device applies a pressure difference to grip the target tissue without the need to enclose it. Inspiration is taken from biological suction discs, as these are able to attach to a wide variety of substrates, varying from soft and slimy surfaces to rigid and rough rocks. Our bio-inspired suction gripper is divided into two main parts: (1) the suction chamber inside the handle where vacuum pressure is generated, and (2) the suction tip that attaches to the target tissue. The suction gripper fits through a ∅ 10 mm trocar and unfolds in a larger suction surface when being extracted. The suction tip is structured in a layered manner. The tip integrates five functions in separate layers to allow for safe and effective tissue handling: (1) foldability, (2) air-tightness, (3) slideability, (4) friction magnification and (5) seal generation. The contact surface of the tip creates an air-tight seal with the tissue and enhances frictional support. The suction tip’s shape grip allows for the gripping of small tissue pieces and enhances its resistance against shear forces. The experiments illustrated that our suction gripper outperforms man-made suction discs, as well as currently described suction grippers in literature in terms of attachment force ( 5.95 ± 0.52 N on muscle tissue) and substrate versatility. Our bio-inspired suction gripper offers the opportunity for a safer alternative to the conventional tissue gripper in MIS.</p