In many countries, Vacuum-Assisted Delivery (VAD) is the most common technique for instrumental vaginal delivery. Current VAD devices require the formation of a typical chignon on the infant’s scalp to achieve the necessary traction forces. This chignon, a swelling on the infant’s scalp, can lead to complications and, in severe cases, even death. This study addresses the question of how a new design for a VAD suction cup can reduce chignon formation while maintaining excellent adhesive performance. Three 3D-printed flexible suction cup designs with varying flexible lattice structures were designed to minimize chignon formation, and a bellow-shaped sealing lip was used to enhance the sealing performance. The performance of the novel designs are tested on an infant head surrogate and compared to a replica of the current commonly used Kiwi OmniCup®. Results indicated a significant reduction in scalp deformation, with the chignon volume ranging from 6.2% to 15.5% of that observed with the Kiwi replica. While the proposed suction cup designs show promise in reducing neonatal injuries by reducing the chignon formation, future work should focus on achieving a larger maximum traction force. ... Read more

Background: Treatment of eye conditions, such as retinal detachment, macular pucker or macular holes, ask for an intervention named ”vitrectomy”. In a vitrectomy, multiple surgical instruments are brought into the eye, to facilitate removal of the vitreous humor. The instruments enter the eye through trocar ports that are placed in the sclera. Post operation, this passageway is removed, leaving an incision wound in the sclera. These wounds that remain after removal may cause complications such as hypotony and endophthalmitis. Current studies suggest that the frequency of these complications decreases when the incision architecture (i.e., the number of incision planes that are used to construct the
wound) , made during insertion of the trocar port, has better self sealing properties. The objective for this study is to develop and verify a surgical instrument that can consistently create the most effective self-sealing scleral incisions.
Method: An analysis is performed that investigates the relation between the incision architectures and the corresponding self-sealing characteristics. This analysis is done through information found in literature and an experiment. In this experiment, incisions with a variety of incision architectures are made in a setup that imitates the characteristics of the
human eye. Based on the analysis, incisions with a bi-planar architecture hold the greatest potential for consistent self-sealing incisions. A set of requirements are formulated that are used to generate a functional prototype that is capable of creating bi-planar incision. This concept consist of a high precision pin and slot mechanism linked to an actuation handle.
Verification of the established requirements and evaluation of the prototype performance are achieved by incisions in silicone slabs (i.e., eye phantoms).
Results: The defined Bi-planar architecture is set to have an oblique plane of 0.500 mm, a vertical plane of 0.250 mm and the angle between the two planes of 60.0◦. The Bi-Planar Incision Mechanism showed to have an mean oblique plane of 0.530 mm (SD = 0.043), a mean vertical plane of 0.248 mm (SD = 0.0286) and a mean angle of 60.08◦ (SD = 2.40).
The incision were performed with an average time to completion of 5.0 seconds (SD = 1.5).
Conclusion Using the Bi-Planar Incision Mechanism showed to be a successful method to make the desired bi-planar incisions. The result showed precise, accurate and fast incisions. The next step is to validate the self-sealing statistics in conditions that resemble those found in the operation room.

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Minimally invasive surgery (MIS) has several advantages over conventional surgery, including reduced damage to the body, less pain, lower infection risk, and faster recovery. However, MIS reduces the amount of space in which clinicians can operate within the body. This often forces them to work around delicate anatomical structures. A new type of instrument that can manoeuvre the body with snake-like movement, also called follow-the-leader (FTL) locomotion, could be a solution. A challenging design aspect of FTL instruments is to conserve the instrument’s shape accurately while the instrument propagates into or retracts from the body. This thesis presents a new device, called the Dullomatic, which can conserve 2D shapes and fits inside an instrument’s flexible shaft. The Dullomatic contains two adjacent mechanical shape memories which alternate between a flexible and rigid state, together forming a shaft. The device can be operated such that it conserves the shape and shifts the shape backwards as the device propagates forwards, or vice versa, to attain FTL locomotion. A prototype of this design was manufactured at a 2:1 scale containing 3 segments per shape memory. This prototype was evaluated by performing four FTL steps over a curved trajectory and measuring the position of the segments after each step. The results show that the device could be operated to accurately follow this path with FTL locomotion. Further research is required to enhance its user interface and investigate its potential for miniaturization. The Dullomatic forms an interesting addition in the field of FTL devices and might be able to aid in further reducing the invasiveness of surgery. ... Read more

The MLD massage is a key component of a lymphedema patient’s treatment. Currently, research is ongoing manifesting a transition from system care to self-care by designing robotic sleeves that are able to perform an effective and safe MLD massage enabling the patient to gain a sense of empowerment and ownership over their treatment and time. This research presents an innovative approach towards the MLD treatment by introducing an intermediate step: the bio-inspired design of the patient training education tool (PTET), a tool which aids the patient in performing the MLD massage safely and efficiently by themselves. The PTET is a pliable and slim sheet that easily adapts to the contours of the limb. Exerting manual pressure onto this sheet induces a colour change at a specific pressure threshold, giving the lymphedema patients a visual sign they have reached the required amount of pressure for this type of massage. The mechanism of colour change is inspired by the cephalopod’s dispersion and aggregation of its chromatophores. This study presents the design and validation of the working mechanism of a bio-inspired flexible colour-changing sheet, and first insights into the adaptability of the design variables and their relation to the threshold pressure, threshold indent and degree of colour change. ... Read more

Vitrectomy is an often performed procedure during eye surgery and requires a high-precision vitreous cutter. The production of these precise and lightweight vitreous cutters sets high demands on the manufacturing process. Trained technicians must assemble the device step by step and continuously check and validate the manufacturing process. Additive manufacturing on the contrary allows for non-assembly mechanisms that can be printed at once without requiring any post-assembling steps. However, a high-speed vitreous cutter design suitable for 3D Printing is not yet presented. This research aimed to deliver a 3D Printed driving mechanism design for a high-speed reciprocating needle used during vitrectomy that does not require post assembly steps from trained technicians. It was established that the driving mechanism should reciprocate two concentric needles by air pressure to cut vitreous. Currently used actuators are investigated and a prior attempt for a non-assembly vitreous cutter is analysed. The diaphragm and bellow-based design were considered a potential solution path. A suitable design for both potential solution paths is made. The bellow design consists of an inner and outer bellow to allow the passage of the needle. The diaphragm concept is already used for the first and only attempt to produce a non-assembly vitreous cutter. This prior attempt is further analysed and it became clear the damping of the diaphragm needed to be decreased to increase the speed of the backward motion. Therefore, a planar spring is added to the dual flat diaphragm design. Finally, the spring-reinforced dual flat diaphragm concept is selected for continuation and tested by using PolyJet prototypes. Tests are executed to determine if the requirements could be met, especially focussing on the speed and force requirements. Different spring shapes and thicknesses are tested. It became clear that the behaviour of the spring-reinforced diaphragms is suboptimal. The return time is higher than preferred and damping is still present in a large extent due to hysteresis. To improve the design it was decided to continue with tests where the start position is relocated to form a pretension and overcome the damping seen especially at the last part of the return stroke. Pretension appeared successful and showed a 98% decrease in return time, but the requirements for the speed could not be obtained. Altering the thickness of the spring led to a sufficient high backward force but did not show direct influence on the speed of the backward motion. Overall, a non-assembly vitreous cutter driving mechanism is made but not all requirements could be met. Exploring design directions which do have some drawbacks should be considered to offer a solution in the near future. Designing a driving mechanism that also requires 3D Printed flexible material, first requires a thoroughly material investigation to identify the mechanical properties and time-dependent behaviour such that a trustworthy design optimization can be made. However, a design for a non-assembly high-speed vitreous cutter is made and with the upcoming developments in the 3D Printing techniques and materials the design might form the basis of a high-speed vitreous cutter. This research tested the most ideal case and gave further insight bringing us a step closer towards a non-assembly high-speed vitreous cutter. ... Read more

Background: In vitrectomy, a type of eye surgery, surgery instruments must pass through an incision in the sclera. The architecture of the incision is of great im-portance to the closure of the wound after the procedure and through that the risk for complications like hypotony and endophthalmitis. Current studies suggest that tri-planar incisions provide better sealing, however for a surgeon it is challenging to pro-duce the desired architecture easily and consistently. The objective of this study is to: “Design and verify a new, reliable and easy to use method to create tri-planar inci-sions for scleral cannulas to limit leakage after extraction of the cannula.”
Method: Analysis of the factors affecting the tri-planar incision method in terms of reliability and ease of use was performed, leading to a set of design requirements. Based on the requirements, different incision methods were explored and compared. The selected method was transformed into a functional prototype, which was subse-quently evaluated on consistency and leakage. The evaluation was done by insertion on silicone sheet, eye phantoms and ex-vivo porcine eyes. The tri-planar incision was compared in leakage to straight and oblique incisions, two other common type of ar-chitectures.
Results: The method performed using a designed device was able to create the de-sired tri-planar consistently. These incisions provided a better seal than a straight in-cision. However, for tri-planar compared to an oblique incision the test was inconclu-sive and further research is needed to distinguish between the two.
Conclusion: As tri-planar incisions can now consistently be made with the use of the new method, further research can be performed to link the number and type of com-plications, like hypotony and endophthalmitis, to the incision statistics.
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Introduction: This research aims to develop a 3D-printed ergonomic handle design for a steerable laparoscopic instrument with minimised part assembly. Steerable laparoscopic instruments are used in minimally invasive surgery (MIS). MIS is a technique where surgeons insert long slender surgical instruments through small incisions of five to ten millimetres in the abdominal wall. According to various studies regarding the ergonomics of laparoscopic instruments, improvements in the control and handle design are necessary. Non-ergonomic design and control, combined with extensive surgery, can cause physical discomfort, muscle fatigue, mental stress, and other complications to the surgeon that can adversely affect the patient. Improvements in the design can overcome inconvenient and uncomfortable movements of laparoscopic instruments to make MIS safer for surgeons and patients. In addition to the improvements in ergonomics, a reduction in assembled parts in current laparoscopic instruments can shorten the assembly time, resulting in lower manufacturing costs. 3D-printing offers design freedom to enable complex structures with minimised part assembly and has the potential to customise the instrument specifically to the surgeon. Methods: The working principles and ergonomics of sixteen steerable laparoscopic instruments were analysed. Requirements were set up from the analysed laparoscopic instruments, handle design ergonomics and control ergonomics to develop an ergonomic handle design. Concepts have emerged from the requirements, and the most promising concept has been developed towards a final design. From the final proposed handle design emerged a working prototype, The LapaJoy. The 3D-printing technique of stereolithography was used to manufacture the LapaJoy. Steering, grasping, bending and locking tests were conducted to compare the retrieved data with the requirements to validate and evaluate the working principle and performance of the LapaJoy. Results: The LapaJoy consists of five assembled parts and allows the surgeon to control the four different functions of the instrument. The surgeon can control the end-effector in two degrees of freedom, lock the end-effector's position, open and close the grasping forceps, and lock the grasping forceps in place. All four functions of the LapaJoy can be performed by a novel two-finger control system using the index finger and thumb. The results show that the LapaJoy can manipulate the end-effector in two degrees of freedom by 20 degrees and lock the end-effector in any desired position. The instrument's grasper is functional, and the grasping forceps can be locked in place upon release of the grasper trigger. However, an analysation showed a reduction in the opening range of the grasping forceps with each opening and closing cycle. Furthermore, a material response wherein deformation of the steering segment's flexure occurred. The steering segment's flexure was deformed by 9.9 degrees after applying almost 1 N to the grasping forceps in the vertical direction. In addition, fatigue and failure of the grasper and joystick design occurred during extensive use and testing. Conclusion: By developing the 3D-printed ergonomic handle design with minimised part assembly, new knowledge was acquired in the possibilities of 3D-printing as a manufacturing technique for laparoscopic instruments. Future research is recommended to increase the steering angle and use more durable materials to create a more reliable product. The instrument's performance showed excellent potential in 3D printable laparoscopic instruments with minimised part assembly. The LapaJoy has the prospect of being an ergonomic, low cost, disposable MIS instrument. ... Read more

In this report a design is proposed for a laparoscopic gripper that can be manufactured with metal 3D printing and polished with mass finishing. The design is a continuation of the development of a laparoscopic gripper that can be 3D printed in plastic. Laparoscopic grippers 3D printed solely out of metal have not yet been presented. Laparoscopic instruments are limited in width to 5 mm, which is bordering the manufacturing limits of selective laser melting 3D printing. The use of 3D printing for medical instruments has the potential to customise instruments specific to patient, procedure, and surgeon. Metal 3D printing can produce complex parts, albeit with a high surface roughness. Post-processing is required to reduce the surface roughness. Mass finishing techniques are a group of mechanical polishing techniques, of which centrifugal disc finishing was selected due to its capability to process parts in bulk without requiring workpiece fixation. To synthesise a suitable design, the processes of printing and polishing were analysed to formulate design guidelines. The analyses were part literature study, part experimental study. The experimental study had the aim to quantify and supplement the guidelines found in handbooks and articles. Using a novel visualisation technique, the polishing of different geometries could be distilled into quantitative design considerations. Here, a marking lacquer was applied to the surface of workpieces, which remained on unpolished surfaces. In this experiment a number of features were used, which corresponded to aspects that had potential to be used in the design. The use of channels was deemed unviable for polishing at the scale of laparoscopic instruments, which required the removal of these from the design. Mass finishing polishing removed the coarse surface structure present on metal produced with 3D printing, and brought surfaces of the test pieces to 0.05 mm below their desired width. Application of the design guidelines to the laparoscopic instrument was focused on making printing and polishing compatible joints. The laparoscopic gripper has two degrees of freedom for increased manoeuvrability. The features that comprise the joint are protrusions and cut-outs, sinusoidal gear arches, and actuation cable guides. Each of these features were dimensioned with values from the guidelines. The joint design required a number of components to be split so polishing access could be guaranteed, specifically for the cable guides. This had the added benefit of having each part be orientated during printing individually. The final design is based on application of the relevant design guidelines, and has been validated using scale models for mechanical stability. ... Read more

Minimally invasive surgery has some major benefits over traditional open surgery for the patient, but makes surgery more complex for the surgeon. Articulating instruments can regain some of the manoeuvrability that is lost by using a small incision. However, in endoscopic neurosurgery such articulating devices do currently not exist, due to scale dependent assembling and manufacturing challenges. We explored the use non-assembly additive manufacturing to circumvent the infeasible assembly and enable production of a 2 mm articulating forceps. Four different designs were made to explore different levels of articulation intricacy, with a distinction in planar or spatial, and concentrated or distributed bending. Eligible 3D printers capable of printing surgical instrument-sized parts including sub 2 mm mechanisms need relatively large clearances between moving parts. This poses a serious challenge that we solved by using compliant grasping and bending mechanisms. Three out of four designs were successfully 3D printed on a 5 mm and 2 mm scale, and their geometrical requirements were validated. The designs fitted through a 2.2 mm dummy trocar, reached bending angles up to 70°, and an forceps opening angle of 40°. The distributed planar and distributed spatial bending design were deemed infeasible due to their lack of bending stiffness upon external forces. The two remaining designs proof that 3D printed non-assembly forceps for neuroendoscopy are possible, with planar and spatial articulation. With these articulating devices, many more neurosurgeries could be executed in a minimally invasive manner. However, simulated surgical tasks should be performed to further test the designs, before they could be commercialised. ... Read more

During a vitrectomy procedure vitreous is removed from the eye with a vitreous cutter, called a vitrectome. This instrument is comprised of two needles that move to cut the vitreous into small pieces before aspirating them. Vitreous cutters are complex instruments that are light and small in size to increase their accuracy. Because of their small size, and complexity, they are assembled by trained technicians with the help of a microscope. It is believed that new technologies such as additive manufacturing (AM) might be able to reduce the manufacturing complexity associated with vitreous cutters. The goal of this study was therefore; "To create a non-assembly driving mechanism for a vitreous cutter that is designed for AM". In order to achieve this goal, the functions of a vitreous cutter were identified, as well as the mechanisms that fulfil these functions in current instruments. Furthermore, the general limitations of AM were researched and listed. Extensive research was done to identify examples in the scientific literature to find linear actuators that were made by means of AM as an integrated assembly. A diaphragm actuator was selected to drive the mechanism based on the limitations of AM, the requirements, and examples found in the scientific literature. An in depth analysis of diaphragm driven vitreous cutters revealed that it would be a challenge to seal the air chamber of the instrument. A new concept was created that used one of the strengths of AM to solve this problem, by creating a compliant interface between the moving needle and the air chamber. A proof of principle prototype was created to quickly test if it would be possible to create movement by sealing the air chamber with differently sized diaphragms. Based on the concept of sealing an air chamber with flexible diaphragms, four concept variations were created.
It was decided to make a series of prototypes of one of these concept variations to study its performance. In total, 9 prototypes were manufactured using material jetting, out of Agilus30 and Vero, without the need of post-assembly. The prototypes were tested by applying a range of air pressure pulses, while measuring the force, the displacement, the actuation time, and the spring properties of the mechanism. With the successful manufacturing of the prototypes, it has been shown that it is possible to produce the novel driving mechanism using current AM techniques without any assembly steps other than the sealing of a cleaning hole to remove support material.  The tests revealed that the spring force of the mechanism was not linear for all materials, and that there was hysteresis present in the mechanism.  Furthermore, it was shown that none of the samples were capable of operating at the desired speed of 8000 pulses per minute (PPM). The soft samples were seen to have the best response time during the backward motion of the mechanism. A new driving mechanism was created in this study that utilized one of the strengths associated with AM. To the knowledge of the author this mechanism is the first of its kind, and has not been previously applied in another instrument. Additional knowledge on the material properties of digital materials is needed to be able to design a diaphragm mechanism that has the appropriate performance characteristics. With additional design efforts and research it could be possible to produce vitreous cutters using AM in a non-assembly manner. This could lead to a future where surgical instruments are manufactured on site and on demand.
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