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13:30   Medical Instruments Chair: Paul Breedveld 13:30 15 mins BIO-INSPIRED SPRING-LOADED BIOPSY HARVESTER Filip Jelinek, Paul Breedveld Abstract: Background – Current minimally invasive laparoscopic tissue harvesting techniques for pathology purposes involve taking multiple imprecise and inaccurate biopsies, usually using a laparoscopic forceps or other assistive devices. The potential hazards, i.e. cancer spread when dealing with tumorous tissue, call for a more reliable alternative in the form of a single laparoscopic instrument capable of repeatedly taking a precise biopsy at a desired location. Aim – Design a disposable laparoscopic instrument tip, incorporating a centrally positioned glass fibre for tissue diagnostics, a cutting device for fast, accurate and reliable biopsy of a precisely defined volume and a container suitable for sample storage. Description – Inspired by the sea urchin’s chewing organ, the Aristotle’s lantern, we designed a crown-shaped collapsible cutter enabling rapid and simultaneous tissue incision and enclosure. Based on a series of in-vitro experiments indicating that tissue deformation decreases with increasing penetration speed leading to a more precise biopsy, we decided on the cutter’s forward propulsion via a spring. Apart from the embedded spring-loaded cutter, the biopsy harvester comprises a smart mechanism for cutter preloading, locking and triggering, as well as a sample container. Results – A real-sized prototype suited for evaluation in a universal tensile testing machine was developed at TU Delft. In terms of mechanical functionality, the preloading, locking and triggering mechanism as well as the cutter collapsibility proved to work successfully. Later in-vitro evaluation will be carried out on animal tissues with respect to the cutter’s incising and collapsing capabilities. Further division of the tip into a permanent and removable segment will enable taking of multiple biopsies mutually separated in individual containers. We believe the envisioned opto-mechanical biopsy tip will be a solution ameliorating time demanding, inaccurate and potentially unsafe biopsy procedures. Acknowledgements – This research was supported by the Center for Translational Molecular Medicine (project MUSIS). 13:45 15 mins IN VITRO BIOCOMPATIBILITY TESTING OF DYNEEMA PURITY® FIBERS IN BLOOD CONTACT Amir Basir, M. Roest, P.F. Gründeman, C. Tersteeg, C. Maas, A.D. Barendrecht, W. Muller, J.A. van Herwaarden, J. Kluin, F.L. Moll, Gerard Pasterkamp, Ph.G. de Groot Abstract: OBJECTIVES: Different materials have been used for vascular and heart valve prostheses. Major drawbacks of current valve prostheses are a need for strong anticoagulants, moderate durability and low resistance to fatigue and tear. Dyneema Purity® fibers are made from Ultra High Molecular Weight Polyethylene (UHMWPE) and are flexible, fatigue- and tear resistant and have high strength. Therefore, prostheses made from Dyneema Purity® fibers might be attractive for use in minimally invasive treatment of valvular and vascular disease. The aim of this study is to test the biocompatibility of Dyneema Purity® fibers In Vitro in blood contact. METHODS: Blood of three randomly chosen donors was used to do three different experiments. First, platelet adhesion on filaments (Ø 15µm) of Dyneema Purity® fibers and Polyester (gold standard) were tested in Polydimethylsiloxane (PDMS) perfusion chambers and visualized by light microscopy. Then patches were studied. Woven patches of Dyneema Purity® fibers were compared with the 5 most commonly used patch prostheses, i.e. a knitted and a woven polyester fabric and 3 different ePTFE patches. Please note that the construction and surface characteristics of these patches are different. Coagulation activation was tested by measuring the thrombin formation over time. Platelet adhesion, activation and aggregation were studied in a flow chamber and visualized with SEM. RESULTS: The platelet adhesion on Dyneema Purity® filaments was significantly lower compared with polyester filaments in the PDMS perfusion chamber experiment (P<0.05). The time to peak of thrombin generation was non- inferior for patches of Dyneema Purity® fibers, compared with the reference materials. Results of the patch perfusion test are being generated now. CONCLUSIONS: The first experiment indicates that Dyneema Purity® filaments are non-inferior to polyester filaments with respect to platelet adhesion in human blood. A woven patch of Dyneema Purity® fibers also appeared non-inferior with respect to thrombin generation compared to the reference materials. The results from the other experiment will provide additional data on the possible suitability of Dyneema Purity® fibers for use in minimally invasive treatment of valvular and vascular diseases. 14:00 15 mins DORA– PATIENT TRACKING IN THE ROTTERDAM EYE HOSPITAL Linda Wauben, Annetje Guédon, John van den Dobbelsteen Abstract: Introduction: Each year 14,000 patients are treated at the six operating rooms (OR) of the Rotterdam Eye Hospital. Most patients are admitted in day-care. The total day-care surgical track involves many steps and many professionals. As the patient flow is mainly adapted to the OR-schedule and less adapted to e.g., ward staffing, the patient flow is disturbed, leading to long waiting times for patients and family. DORA (Digital Operating Room Assistant) supports staff with automatic and accurate information about the patient’s location in the surgical track. It reduces waiting times and improves patient and employee satisfaction. The objective of this study is to investigate surgical patient flows and improve these patient flows by implementing DORA. Methods: In a pilot study (8 days) observations and time recording of patient flows were performed. After the pilot RFID technology was installed and patients received a tag attached to their patient identification wristband. Patients were tracked for ten weeks. In both studies 31 moments were recorded (e.g., time entering/leaving hospital, time entering/leaving OR). Duration of actions and waiting times for patients at several stages were calculated. In addition, a DORA-user interface was designed, displaying the patient’s location in the surgical track and the anticipated time for moving to a next step. Results: During the pilot 222 adults were tracked. Analysed data showed that 157 patients (71%) arrived earlier then necessarily at the ward (average: 19min, STDEV: 15min, maximum: 1h14min), and 37 patients arrived late (average: 11min, STDEV: 13min, maximum: 1h8min). Patients spend an average of 5h38min in the hospital (STDEV: 1h47min, maximum 12h37min). At the Holding, patients had to wait an average of 22min (STDEV: 19min, maximum: 1h34min) between final preparations for surgery and transportation to OR. The response time of ward nurses to requests for picking up patients at the Recovery was 7min (STDEV: 8min, maximum: 1h8min). Twenty-four patients were picked up immediately after bringing another patient to the Holding. Data obtained via the RFID tags is now analysed and will be presented at the conference. Also the design for the DORA-user interface will be presented. Discussion: The results show that the waiting times make up a considerable part of the duration of the entire surgical track and show that the waiting times are highly variable. RFID technology and the DORA-user interface automatically track the patients. It provides the professionals with ‘real time’ information about the patient’s location and the anticipated time for e.g., leaving the ward, start of surgery. It can also improve patient scheduling, patient satisfaction and the efficiency of patient transport. 14:15 15 mins REALIZATION AND CONTROL OF A SWARM OF MAGNETOTACTIC BACTERIA Marc Pichel, I.S.M. Khalil, Sarthak Misra Abstract: Over the last two decades, a range of minimal invasive surgery (MIS) techniques have been presented to reduce patient recovery time and risks of infection during the surgery. In MIS, incisions are significantly small, as opposed to conventional surgery [1]. The operating range of the needle insertion is limited by the reachability of the needle tip within the human body due to the presence of obstructions. Therefore, effort has been dedicated to the development of magnetic drug carriers (e.g. microparticles, microrobots, magnetotactic bacteria) with real-time control. These magnetic drug carriers can be steered to the location where drugs need to be administered. However, steering a real-time fully controllable magnetic drug carrier is a challenging task and requires both tracking and characterization of the position and the properties of the magnetic carrier, respectively. Utilization of self-propelled magnetotactic bacteria (MTB) as magnetic drug carriers eliminates the need for external means of propulsion. In order to model MTB, we characterize their magnetic dipole moment to realize the dynamical model of a single MTB [2]. In addition, we use this model to design closed-loop control system to control the motion of the MTB inside capillary tubes and micro fluidic maze [3, 4]. The next step towards transport and delivery of greater amounts of drugs requires higher MTB density. Therefore, a method is needed to investigate the synchronized and controlled characteristics of a swarm of MTB. In this study, the viability of controlling a swarm of MTB is tested in vitro using magnetic fields to steer the MTB towards a mechanical constriction, as shown in Fig. 1. In our approach, a uniform magnetic field is imposed to force the MTB into one direction parallel to the longitudinal axis of the funnel (Fig. 1). Thus changing a forward driving thrust force along the magnetic fields into a shifted force in the direction of the center of the funnel, to form a swarm of MTB at the 30 μm wide semi-circular recess. Second, the magnetic field is reversed to move the swarm of MTB away from the funnel recess. Subsequently, magnetic fields are generated to control the swarm of MTB. Through the guidance of open- and closed-loop control, the average velocity, region-of-convergence (ROC) and accuracy of controlling such a swarm are investigated. A wide distribution of the population can affect the average velocity of the swarm of MTB. We compare the velocity of a swarm of MTB to the velocity of single MTB. Furthermore, the diameter of the ROC determines the accuracy of the control system in the steady-state. 14:30 15 mins DIGITAL OPERATING ROOM ASSISTANT: A MONITORING SYSTEM FOR OPERATING ROOM DEVICES Annetje Guédon, Linda Wauben, Marlies Overvelde, John van den Dobbelsteen Abstract: The increasing number of new technologies in the operating room (OR) has made the surgical environment more complex, which increases the risk on technical incidents [1]. Missing or malfunctioning equipment often delay the procedure and are a source of incidents during procedures. The aim of this study is to set up a system to monitor the presence and the safety status of OR devices, to alert the staff about irregularities and to simplify the notification of a malfunction. The proposed system was designed to be implemented in an OR complex of a Dutch teaching hospital consisting of four ORs. The tracking technology, developed in collaboration with LogiSense, is based on radio frequency identification technology (RFID). Before the tracking was implemented, the interference of the RFID tags and readers with the OR devices was tested to ensure safety. Moreover, the location of the readers in relation to the floor plan of the OR complex was optimized. Also, a graphical user interface (GUI) was designed for access to the hospital’s technical facility management system and to provide feedback on device status to the OR staff. For this study, a selection of 100 OR devices was made. The system is able to instantly determine the location and maintenance status of all devices in the OR complex. The developed software environment and GUI provides the opportunity to alert the staff about irregularities and simplifies the notification of a malfunction. The monitoring system is currently being tested for a pilot period of six months. All the malfunction notifications are saved in the hospital’s technical facility management system. The users will be interviewed on their experience of the monitoring system. In 2011, 121 malfunctions were notified for this OR complex. By automatically monitoring the status of OR devices an increase in registered notifications compared to the previous years is expected. This will provide valuable insight in the frequency of incidents and recurrence of malfunctions of individual devices. On a longer term, such a system is expected to prevent irregularities and increase the safety related to medical OR devices. 14:45 15 mins REVIEW OF MULTI-BRANCHED INSTRUMENTS FOR NATURAL ORIFICE TRANSLUMENAL ENDOSCOPIC SURGERY (NOTES) Ewout Arkenbout, Paul Breedveld Abstract: Natural Orifice Translumenal Endoscopic Surgery (NOTES) is a surgical procedure where the surgeon uses flexible endoscopic technology to perform laparoscopic procedures beyond the confines of the gastrointestinal tract. Advantages to this approach include faster patient recovery, less adhesions, absence of abdominal wound infections and less postoperative pain. Since 2006, when the key challenges for NOTES were first identified, several multi-branched instruments, also commonly referred to as multi-tasking platforms, have been developed, with features superior to standard Duel-Channel Endoscopes. These features include improved maneuverability and stability, off-axis visualization and multiple actively controlled instrument branches to facilitate triangulation (i.e. the ability to apply traction and counter-traction to tissue). Most of these instruments are still under development, and none have been commercialized so far. A literature study has been performed to ascertain the state-of-the-art in multi-branched instruments. The identified instruments have been analyzed and categorized with respect to their control strategies and the accompanying (in-vivo) distal tip and/or instrument branch actuation. It is found that all multi-branched instruments, both fully mechanical as well as electromechanical master-slave systems, require a minimum of two operators to actively control all available degrees-of-freedom (DOF), or one operator to intermittently switch between control modalities. In addition, most instruments use a combination of direct and indirect control to allow for the simultaneous constant (re)positioning of the entire endoscope and actuation of two or three separate articulating branches. To date, several multi-branched instruments have been tested and found to allow surgical NOTES procedures to a certain extend. However, the complexity in control of all the separate DOF, the relatively large instrument dimensions, and the insufficient functionality of the branches to perform complex surgical tasks, makes human NOTES procedures thus far unfeasible and unsafe. For this reason, a new research project entitled “Bio-Inspired Maneuverable Dendritic Devices for Minimally Invasive Surgery” has been initiated at the Delft University of Technology, focusing on the highly challenging field of endonasal skull base surgery. The project aims to develop a multi-branched or dendritic maneuverable instrument based on the cable-ring mechanism. This working principle is to be applied to develop a fully mechanical, preferably one-handed, instrument with cable-actuated branches and intuitive direct control strategies.