Background: An endomyocardial biopsy (EMB) is an invasive procedure where biopsy samples are taken from within the heart for diagnosis of different myocardiopathies and or heart transplant rejection monitoring. During EMB procedures, a minimum of five tissue samples are required to be taken from the heart wall for investigation. Current bioptomes are not able to retrieve more than one sample at a time and therefore need to be re-inserted at least four times. This can lead to complications such as air embolisms. The goal of this design study was to develop a novel cardiac bioptome for endomyocardial biopsies that can take and store multiple biopsy samples during a single insertion. Design: The bioptome developed in this study had two major functionalities, resection of myocardial tissue and storage of multiple tissues. Each functionality could be divided into multiple sub-functionalities. From these functionalities the design requirements followed. Afterwards, the alternatives for each subfunctionality were explored. For the tissue resection, different possibilities for the method of resection, position of the resection tool, direction of resection forces, and motion of resection, were explored. For tissue storage, different possibilities for the storage system, tissue transportation, and sample loss prevention were explored. Following this exploration, multiple design concepts were devised. Two of these concepts, the ’corer’ concept and ’ovipositor’ concept were developed further. These two concept were compared and the ’corer’ concept was chosen as the most viable option. Prototypes of this concept were developed and tested for the functioning of its working principle for tissue resection and storage and for the functioning of the actuation mechanism. Results: The experiments showed that the end-effector of the bioptome works as expected and that thus the working principle of the ’corer’ concept for resection and storage of biopsy samples functions as intended. The experiments also validated the functioning of the actuation mechanism within the handle. The experiments however also showed that the flexible shaft was unable to correctly transfer the motion from the actuation mechanism in the handle to the end-effector. Discussion & conclusion: More suitable materials are required for future prototypes to improve motion transfer. Furthermore, a steerability functionality should be added to the design to make the bioptome fully functional for EMB procedures. The final design should be tested in an environment more closely resembling the clinical scenario. If these tests are successful, it can be concluded that the bioptome can indeed improve endomyocardial biopsy procedures.

Access to prosthetics is very limited to many potential users, while the need is high. There are two main reasons for this that both are related to the production of prosthetics: the lack of skilled people and high costs. Minimized assembly production using 3D printing could be a solution: no training is required, assembly takes only a short amount of time and cheap materials can be used. Besides, 3D printing is a good method for customization. Therefore, this study proposes a 3D-printed finger for a bodypowered hand prosthesis with minimized assembly. The design approach is the following. First, the human finger anatomy is studied. Then, a stylized version of the human finger is made that includes only the functions required for the prosthesis. Finally, the design principles of the stylized finger are evaluated and structurized. Based on the design principles, a finger for a prosthetic hand is designed and a prototype is developed. The prototype is produced with an Ultimaker 3 using a rigid and a flexible material in one print. The evaluation of the prototype shows promising results. The finger is suitable for a hand prosthesis that can perform an adaptive power grip and a pinch grip. The mass of the finger is 17 grams, which makes the finger comfortable to wear. An actuation force of only 16 N is required to fully bend the finger. Minimized assembly and cheap production are achieved: only four assembly steps are required and the material costs are only 1.68 euros per finger. In conclusion, the prototype shows a promising step in the direction of a hand prosthesis that is affordable, functional, body-powered, and has minimized assembly

Introduction: Prosthesis simulators are essential tools for research and rehabilitation. They can be used to increase the amount of participants in research studies or to assist in rehabilitation. The main goal of this master thesis is to design a functioning prosthesis simulator, which can be used with commonly used terminal devices. A second goal is that the design needs to be accessible for multiple research groups and rehabilitation centers. The last goal is that the design needs to solve the problems that currently exist with prosthesis simulators: sub-optimal position of terminal device and lack of restriction of degrees of freedom of intact arm. Methods: The design requirements were based on the goals and a function analysis which included the state of the art of prosthesis simulators. Based on these design requirements the final design of The Delft Pro Simulator was developed. The design method that was used was a combination of the basic design cycle and the Fishtrap model. Results: The Delft Pro Simulator is a novel 3D-printable design that is accessible for multiple users. The design consists of only 14 parts and weighs 356 grams. The design is minimal-assembly and the material cost is low. The simulator is able to constrain pro- and supination of the intact arm. It can be worn on the left or the right arm. The socket can be used with all terminal devices with the American standard bolt (1/2"-20) and the European standard bolt (M12x1.5). A user tested the functional performance of the design with two standardized tests, the Box and Blocks Test and the Nine Hole Peg Test. Discussion and conclusion: This report presents a novel prosthesis simulator design. The goals have all been achieved. The design can be used with all commonly used terminal devices. Use with a myoelectric device has not been tested, but should be possible with minor adaptations. Most parts of the simulator can be 3D-printed except for some parts which are very accessible. The design can be used with two possible orientations of the terminal device with respect to the intact hand (dorsal and palmar). The simulator is able to accurately simulate transradial limb absence by constraining pro- and supination of the intact arm, while leaving flexion and extension free.

Gripping slippery, compliant, and irregular tissues during MIS is often challenging using a conventional gripper. A force grip has to compensate for the low friction coefficient between the gripper’s jaws and tissue surface. This study focuses on the development of a suction gripper as an alternative for the well-known tissue gripper. Suction technology applies only normal forces to grip the tissue without the need to enclose it. Inspiration is taken from biological suction discs. These are able to attach to a wide variety of substrates, varying from slimy surfaces to rough rocks subjected to chaotic streams. The designed suction gripper is divided into two parts; the suction chamber inside the handle where vacuum pressure is generated, and the suction tip that makes contact with the target tissue. The suction tip fits trough a 10 mm diameter trocar, and unfolds in a larger suction surface when being retracted from the trocar. The suction tip is built in a layered manner. Each layer focuses on a specific function to allow for safe and effective tissue handling: 1) Foldability, 2) Air Tightness, and 3) Slide ability. The footprint of the tip focuses on its adaptability to different substrates. Experimental validation of the suction tip’s attachment performance on slippery and flexible phantom tissue showed a maximal attachment force of 3.27±0.15 N. The occurrence of leakage appeared to be the main reason that larger attachment forces are not reached. The proposed prototype of the suction tip provides a base for further research to develop a reliable and effective tissue gripper actuated by suction.

Background: Colonoscopy is a successful screening method to prevent colorectal cancer (CRC). Biopsies are performed from suspicious tissue spots during the colonoscopic procedure to find cancerous polyps in an early stage of the disease. However, taking multiple biopsies is rather time-consuming and requires many repetitious actions from the gastroenterologist. The current state of the art instruments either do not solve this issue or do not meet the user requirements. The goal of this study was, therefore, to design a new endoscopic instrument to store multiple biopsies during a colonoscopy. Methods: The input from different gastroenterologists, together with risk analyses, has resulted in the lists of requirements for the device. These requirements have defined the design space for the development of the instrument. The tip functionalities were subdivided into five design challenges: integrate, transport, remove, store and secure. The solutions for these challenges were combined to generate concept directions. Within these directions, concepts have been created and analysed, which resulted in the final design, 'the Biopsy Containuer'. Different prototypes have been made from this design to evaluate the functionalities of the instrument and receive the opinion of potential users. Results: The evaluation showed that the developed prototype is able to remove a biopsy from the biopsy forceps and store five biopsies without loss or change of order inside the container of the instrument. Besides, potential failure movements were investigated, and they did not result in breakage or malfunctions. The participating gastroenterologists in the user assessment were, in general, pleasantly surprised about the potential of this instrument. Performing six biopsies using the Biopsy Containuer results in a time reduction of 44 %. Discussion and conclusion: When taking the learning effect found during the user assessment analysis into account, the time to perform six biopsies is reduced by 57 %. More research is required to evaluate the influence of bowel tissue on the instrument functionalities and the most suitable handle design. The next prototype iteration can include the use of one single polytetrafluoroethylene (PTFE) tube and laser cutting to create the tip structures. The Biopsy Containuer is able to store multiple biopsies during a colonoscopy, and the potential purpose in endoscopic procedures besides colonoscopy could be useful.

Endoscopic instruments are integral components of minimally invasive procedures, widely used for diagnoses and treatment of diseases. When navigating the endoscope, it should experience a minimum of friction, while an increase in friction is beneficial for performing the medical procedure. Friction can be reduced by squeeze film levitation, where air is trapped and pressurized between two surfaces by vibrating one of these surfaces. The squeeze film levitates the two surfaces away from each other, hereby reducing friction. Squeeze film levitation between a rigid curved surface and a soft surface is still poorly understood. Also, a proof of concept of a friction modulation mechanism for endoscopes is not yet available in the research literature. Therefore, this paper describes the design and experimental validation of an ultrasonic vibrating ring that can actively modulate friction by generating a squeeze film. On a steel surface, the friction is reduced considerably. However, on the two soft surfaces described in this paper, the reduction of friction is absent.

During endonasal pituitary surgery - an approach of skull base surgery - long slender instruments are inserted through the nose of the patient, in order to remove a pituitary lesion. One of the instruments which is repeatedly used is the surgical punch, which is able to remove pieces of bone in order to create access to the lesion. The drawback of the currently used surgical punches is twofold: first of all, they do not allow for rotation of the tip relative to the handle orientation in order to align the tip properly to the bone to be cut. Furthermore, the successive introduction and extraction of the instrument from the operational area after each cut, increases the risk of introducing bacteria and slows down the procedure. A novel surgical punch was designed and developed called NeuroPunch. Throughout the course of this study, a human-centered design approach combined with a systematic engineering process was followed leading to several conceptual solutions for different functional parts of the NeuroPunch. By combining these conceptual solutions, a design was set for a first functional prototype including an ergonomic handle, a mechanism for the storage of punched bone pieces, and a mechanism for rotating the tip relative to the handle orientation. A first evaluation of the functional 1:1 scale prototype with end users shows positive results indicating that the NeuroPunch might be a proper replacement for the currently used punches in endonasal pituitary surgery. Several iterative steps are required to produce a fully functional prototype of the NeuroPunch which can be evaluated in a preclinical setting (e.g. cadaver study). The NeuroPunch shows much potential to be used for other surgeries as well, and it is demonstrated that the NeuroPunch will enable a safer and more comfortable endonasal pituitary surgery while potentially reducing operating time.

Background: During minimally invasive procedures, tissue damage can be limited by using smaller incisions and by using naturally occurring body orifices to reach the intervention site. During these procedures the need can arise to transport tissue. Think of a biopsy or the removal of polyps. This calls for a tool that can transport tissue and is also flexible such that the tool can be introduced via natural occurring body orifices. Currently either suction based techniques or forceps are used for these procedures. However, both show suboptimal behaviour. Friction-based transport, which is based on the egg laying principle of parasitoid wasps, is not prone to these sub-optimal behaviour modes but is not yet used in flexible systems. Methods: A mechanical analysis was conducted to generate an overview of the challenges that arise in flexible friction-based transport. This resulted in a list of requirements based on which possible concept solutions were analysed. Themost promising design for a flexible friction-based transport mechanism has a flexible shaft that consists of a number of wire ropes in combination with ring magnets. This shaft was manufactured and validated by transporting gelatin tissue phantoms with different material properties with the shaft in straight and in a curved position. After validation of the flexible shaft, an ergonomic handle was designed resulting in the final prototype. This final prototype was also tested by transporting gelatin tissue phantoms. Results: From the results can be concluded that the flexible shaft is able to transport tissue phantoms with different material properties while in straight and curved (R=59mm) position. The final prototype is showed that continuous transport was possible from the tip of the flexible shaft to the end of the handle with the shaft in straight and in curved position. The position of the shaft (straight vs. curved) did not result in a significant difference in the transport rate. Discussion and Conclusion: It can be concluded that friction-based transport is possible in a flexible tool. The mean transport rate in straight position ( 2.3 § 0.29 mm/cycle) is comparable to the transport rate of a rigid friction-based transport mechanism with comparable dimensions. This new flexible friction-based transport mechanism shows great potential to be beneficial for a number of medical procedures.

Introduction: When navigating through tight and delicate environments, steerable tools are highly desired. Follow-the-leader locomotion, as in the biological snake, is a solution that is obtained with shape memory control. The often used electric equipment to control the shape makes the current state-of-the-art of snake-like robots too complex. This thesis focused on a snake-like system using mechanical shape control to generate forward motion, to analyze the motion and comment on the expected behavior. Method: A 3D Simulink model was created with friction between the snake-like system and the surroundings as an important relation. A pre-defined sinus wave was passed through the snake-like system to analyze the motion. A low-cost, 3D printed, prototype was developed to validate the friction relation of the model. The prototype contains a belt feature with pre-defined path as shape control system and a snake-like system with four wheeled segments. Different configurations were assessed in the model by changing the wheel axis length, sinus amplitude and sinus frequency. Results: The prototype validated the realistic friction parameters in the model. Given the results of the model, the snake-like system creates forward motion by pushing against the surroundings when a sinus wave is pushed through the system. The wave parameters have a significant influence on displacement. When the configuration of the snake-like system creates more friction with the surroundings, the system is able to push itself further forward and generates more forward displacement. Conclusion:It is demonstrated that forward motion is possible when a snake-like system is connected to a mechanical shape control system. Now, the next step is to investigate random paths, to enable adaptable mechanical shape control being applied.

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.

Background: Minimally invasive surgery (MIS) is a surgical procedure which is characterized by inserting long and slender instruments through small porthole incisions. On many occasions tissue will have to be extracted from the operation site through one of these small portholes, therefore the sheaths of the instruments that are inserted into the body are limited in diameter. Less than optimal functioning of the transport of tissues which occurs within currently available transport mechanisms in laparoscopic instruments can be attributed to the selected method of transport, i.e.: aspiration (also commonly known as suction). The combination of modes of less-than-optimal functioning are referred to within this report as sub-optimal transport behaviour. The different modes of sub-optimal behavior limit the transport rate and the reliability with which the tissue can be extracted. Methods: An analysis of the modes of sub-optimal behavior was used to formulate a list of qualitative and quantitative functional requirements which were used in order to produce several conceptual solutions. These conceptual solutions were subsequently divided into categories which are mutually exclusive and collectively exhaustive (the ACCREx method). The most promising conceptual solution was developed into a prototype and is based on the egg-laying needle in insects. The prototype was subsequently subjected to a test procedure in order to determine if it was able to transport tissue and to investigate several factors which may influence the transport rate. The effects of the gelatin mixture density, particle presence, motion sequence were assessed in several sub-experiments. In addition, minced meat was transported in order to accurately mimic morcellated tissue. Results: From the results of Sub-experiment I it can be concluded that there was a statistically significant difference in inverted transport rate between the different batches of pure gelatin artificial tissue mimicking material. The highest ITR was attributed to mixture D2. From the results of Sub-experiment I it was also concluded that there was no statistically significant difference in inverted transport rate between the different batches of grainy gelatin artificial tissue mimicking material. The addition of particles was not statistically significant. Statistical analysis between the hexasected motion sequence (DH2) and trisected motion sequence (DT2) show that there was no significant difference in inverted transport rates. Sub-experiment III shows that the prototype was able to transport compacted minced meat. Conclusion: The prototype has shown that the friction-based transport principle has the potential of becoming a viable and reliable alternative to suction as a transport method within laparoscopic instruments. Future work should be directed towards improving the speed with which transport occurs, to investigate what improvements can be made to increase the reliability and the development of the proof-of-principle prototype into a fully functional medical device.

Background: When a suspicious lesion is detected, a thorough examination is essential for the diagnostics of the lesion. Information about the nature and character of the lesion is crucial for the determination of the disease and an appropriate corresponding treatment plan. Taking a biopsy plays an important role in this examination. A biopsy is the removal of a tissue sample from a living organism. The aim of the biopsy is to provide a sufficient and representative part of a lesion, which will enable a thorough examination. Unfortunately, the diagnostics of a biopsy is not always as accurate as desired. Core-needle biopsy is a commonly used minimally invasive biopsy technique. This technique uses a needle, with a varying size between 1.3mm to 2.1 mm, to cut away a tissue sample from a lesion. Biopsies taken with core-needle instruments do not always represent the lesion sufficiently. It is often hard to determine the exact lesion site, and to know if the needle has indeed taken a biopsy from the lesion. To prevent non-diagnostic results from the biopsy, multiple samples should be taken from the lesion site. Common core-needle methods currently obtain a single biopsy sample per insertion. As multiple specimens must be obtained, multiple insertions of the biopsy instrument are required. The aim of this research is to design a single-insertion multiple specimen biopsy instrument. This design will be developed and evaluated on its performance and functionality. Methods: A list of requirements was setup to determine the conditions which comprise the design. Next to the requirements, a functional analysis was carried out which divided the functions of the design into three main functions. A, the insertion of the device into the lesion, B, the actions required to obtain a multitude of samples, and C, the retraction of the instrument from the body. The actions to obtain a multitude of samples, are subdivided into five actions: (1) the instrument must collect a tissue sample, and (2) enclose this tissue sample into a container. (3) This container must be transported through the instrument. And subsequently stored inside the instrument, (4). Finally, (5) the instrument must be reloaded. This sequence of actions can be repeated until a number of specimens have been obtained. Using these five actions as a lead of the design process, conceptual designs were created. During the design process inspiration was found in firearms. The storing of bullets and reloading mechanisms found in guns could help find solutions to the storing and reloading functions of the biopsy instrument. For each action a conceptual design is developed, and finally these five conceptual designs are combined and elaborated, resulting into one final design. A prototype of the final design was developed and evaluated. The prototype was validated on three different aspects: the ability to obtain multiple biopsy samples through a single insertion, the ability to use the prototype in accordance to the intended use, and a comparison between the prototype and an existing biopsy instrument in terms of procedure duration. For each of these aspects the prototype was validated in three different proof of concept experiments. Results: The prototype proved to successfully be able to take a multitude of biopsy specimens through a single insertion. Next to this initial evaluation, the intended use of the instrument is also successfully performed by the prototype. The last evaluation of the prototype, has shown that the procedure time of the prototype to take a multitude of samples is longer than the procedure time to take a multitude of samples using and existing biopsy instrument (TruCore II). The prototype took 5 minutes and 7 seconds, whereas the existing biopsy instrument took 3 minutes and 50 seconds to obtain multiple tissue samples. Discussion and Conclusion: The fabricated prototype has proven that it is able to take multiple tissue samples through a single insertion. This multitude of samples can be used to improve the diagnosis accuracy of core-needle biopsy. The functionality of the prototype is in accordance to the intended use. This intended use provides an indication of the possibilities of use of the prototype. The procedure time of the prototype can be decreased by further improving the usability of the design. Future research can focus on a more elaborate evaluation on the accuracy of the instrument. Furthermore, future work can be carried out on decreasing the instrument length of the current design. Another research can be done on possible ways to implement a semi-, or even a fully-automatic reloading and transportation mechanism on the now manual operable instrument. With these additional future improvements, this initial proof of concept prototype has the potential to become a fully functioning biopsy instrument.

An intracranial aneurysm is a bulge in the cerebral vasculature. The rupture of an aneurysm results in a brain bleed. As a consequence, most patients become severely handicapped or may even die. Preventive treatment with endovascular coiling is controversial due to the high risk of complications. These complications are partly caused by the current uncontrolled delivery of coils to the aneurysm. While recent developments in microcatheter design allow for improved positioning, no method has been devised to model and control the tension applied by the coil on the aneurysm wall throughout a coiling procedure. This thesis aims to come up with a method to improve the safety of aneurysm treatment. This thesis presents a new way to dynamically model an endovascular coil and its interaction with a microcatheter and the aneurysm wall throughout a coil deployment procedure. The main advantage of this model is its low computational complexity allowing real-time control computation. A control architecture is presented that enables regulation of the contact force between the coil and the aneurysm wall while obeying the constraints imposed by the equipment and the environment. The presented architecture comprises an augmented energy-shaping controller working in parallel with a constraint preservation controller. This thesis shows that this control architecture asymptotically stabilizes the aneurysm wall tension at the desired value throughout the coil deployment procedure. This work provides a basis for modelling and control in future experimental validations. Therefore, this work is a promising first step in the modelling and control of robotic systems for neurovascular interventions and a step forward in the preventive treatment of intracranial aneurysms.

When inserting a flexible endoscope into a human colon during colonoscopy, limitations in the endoscope design can cause medical implications such as excessive colon stretching and buckling of the endoscope shaft. This thesis proposes a novel propulsion mechanism design for flexible endoscopes which changes the method of insertion as a way to prevent these implications. As inspiration for the design an analogy is drawn between plant roots growing through tortuous cracks in soil and flexible endoscopes moving through a tortuous human colon. The analogy was found to be relevant, resulting in eight biological features of which seven were suitable as a potential solution in the development of a flexible endoscope. Of these seven suitable solutions, apical extension and variable stiffness were implemented as functions in the proposed propulsion mechanism. The focus of the design process on these two functions ultimately culminated in a proof of concept flexible, extending endoscope design dubbed the Flextendoscope. The Flextendoscope consists of an inverted tube mechanism which can propel the endoscope through apical extension combined with a fiber jamming mechanism that can vary the bending stiffness. The concept design is found very promising as it theoretically allows insertion of a highly compliant shaft which is also able to provide the high tip rigidity required at the surgical location after insertion. Although evaluation of the Flextendoscope prototype validated the feasibility of the proposed proof of concept design, the performance of the apical extension function was of a more limited success. Due to internal frictional resistances the prototype shaft only extended under the lowest evaluated pressure (0.5 bar) and required a high manual force (up to 119 N) to do so. The behavior of the variable stiffness function on the other hand was found to be very desirable. The bending stiffness of the prototype increased with internal pressure level as well as radial deflection, showing initial elastic deformation followed by hysteresis. It showed considerable stiffening at a convenient threshold pressure of 0.7 bar, slightly above the pressure at which the shaft is extended. Future iterations of the Flextendoscope design should focus on overcoming the internal frictional resistances that limit the apical extension of the current design. They can do so by multiplying the number of inverted tubes inside the shaft. This multiplication would enclose the sliding shaft material of each inverted tube within their own central lumen thus avoiding contact between the sliding shaft material and other stationary components in the design, preventing frictional interactions. If the frictional resistance is overcome the Flextendoscope design could prevent colon stretching during insertion of an flexible endoscope and inherently prevent shaft buckling. The prevention of these implications by the Flextendoscope design could ultimately lead to colonoscopy becoming an easier, safer and less painful procedure with a higher success rate.

The materials we encounter in our every day lives already extend beyond the traditional materials of wood, metal, ceramics and glass. The characteristics and behavior of materials and material composites are continuously being tweaked. The introduction of new materials that can respond to inputs from the environment has brought about a new movement for material development and interaction design: computational composites. A computational composite is capable of sensing inputs from the environment, processing and controlling the consequent expression or formation of the material. The aim of the thesis was two-fold: to design and develop a soft bodied mechanism inspired by the movement of a caterpillar, using a Shape Memory Alloy-based (SMAs) composite, and to design material concepts based on the qualities of the composite. This was an explorative project, investigating the application of a bio-inspired approach and the Material Driven Design (MDD) approach to the development of a moving material. The first phase of the project focused on uncovering the technical aspects of a SMA-based composites and its relation to a computational composite. To understand caterpillar locomotion, a thorough study on its anatomy and locomotion strategies was performed. A qualitative study on how designers interpret caterpillar-like motion lead to four interesting movements, which were further developed in moving SMA-based composites from silicone and 4D printed textile. One SMA-based composite was selected for further improvement of the mechanism to be capable of translational caterpillar-like motion. The mechanism can also be interpreted and applied in other ways, and thus the experiential characteristics of the material were uncovered to define a material experience vision for further applications. Through a creative session and ideation phase three material concepts were proposed, suited for three types of user input on the computational composite: none, indirect and direct. The ultimate purpose for the material would be to sensitize people to the idea of a world where materials move from passive objects to active elements in our daily lives. It is recommended to do more research on the composite and to apply the materials experience vision to applications beyond every day objects and into the more innovative field of computer interface design and human-material interaction.

Abstract—Spinal fusion surgery is an operation in which two or more adjacent vertebrae are rigidly connected, with the goal to remedy spinal instability, deformation of the vertebrae, or a herniated intervertebral disc. Vertebrae are conventionally fixated by means of pedicle screws, the downsides of which are accidental cortical wall breaches during drilling and poor holding strength of the screw. The holding strength of the bone anchor may be improved by increasing its contact area with the hard cortical wall of the vertebral body. To accomplish this, a curved hole needs to be made along the inside of the cortical wall. This research presents the design, manufacturing, and testing of a bone drilling device, that is flexible in one plane. To this end, the drill was developed on the basis of the tsetse fly’s proboscis, which is a mechanism that uses a cutting surface with its axis of rotation perpendicular to the drilling direction. Implementing this cutting motion has several advantages over conventional drilling: It facilitates using leaf springs as a flexible transmission, and it is not limited to drilling round holes. A prototype was built and tested on Sawbones closed cell foam, which closely mimics the mechanical properties of the cancellous bone found in human vertebrae. The prototype was capable of effectively cutting through foam with densities up to 10 pounds per cubic foot (PCF) with a feed rate of 50 mm/min. The ability to deflect off and follow a simulated cortical wall was also tested, and proved to be effective up to an insertion angle of 15˚. The bio-inspired drilling device presented in this research opens up new possibilities in the development of flexible drilling for a wide variety of orthopaedic applications.