Endoscopy is an essential medical procedure that is used to diagnose a large variety of conditions. Endoscopes are traditionally manually inserted by an operator and during this process the mechanical movements of the endoscope may cause complications. Self-propelling endoscope designs have been proposed which pull themselves through a lumen. This may reduce trauma and operator skill required in comparison to traditional endoscope designs. This study proposes a novel locomotion mechanism for use in self-propelling endoscopes and seeks to assess its feasibility.

A robot was built which may locomote using in an inchworm-like manner using ultrasonic friction modulation. It was then tested on tracks designed to model the conditions in which an endoscope operates. It's performance and robustness of motion was then measured and evaluated for use in endoscopy.

The robot locomoted at a maximum speed of 15.6mm/s when actuated inside a PLA track, achieving faster performance than other self-propelling endoscope designs. However, it was prone to perturbations and was unable to traverse an elastic substrate or a track modeling a human airway. These findings validated that inchworm-like locomotion using friction modulation is feasible and that it currently presents some potential benefits in endoscopy. Further work is required to assess the performance of this locomotion mechanism over natural tissues and to improve its resistance to perturbations.

Minimally invasive medical procedures often require catheters, endoscopes and other devices to maintain position at a specific site in the body, to cut and remove tissue or for diagnostic purposes. Due to tool force exerted by the surgeon or the natural processes of the body, such as the activity of the heart or the lungs, the inserted device can dislodge or migrate from its intended location. Existing solution focus on stabilizing the tip, following high localized pressure, this can create tissue damage or even perforation. Hence, it can be beneficial to create stabilization over the full length of the catheter. I investigated the use of electroadhesion i.e. using electricity to adhere to the tissue wall. I created a scaled-up, flexible, electroadhesion stabilization proof of concept, consisting of two opposite-charged electrodes in a helical pattern, embedded in silicone rubber. Friction experiments were performed on the catheter proof of concept on two copper half-tube substrates. One of the three flexible scaled-up catheter samples showed an increase in the average dynamic friction coefficient of 10.2% between 0 and 2500 V for the 22 mm diameter substrate. The two other samples showed no or limited increase in friction, attributable to manufacturing differences. Predicting coating thickness is essential, as the coating is the determining factor for the performance of the electroadhesion device. The catheter showed potential, however, improved adhesion performance is required for feasibility on a smaller scale.

Sliding robotic devices are often employed in sensitive applications, such as medical procedures. These devices rely on frictional interaction with their environment to generate locomotion, which can be significantly enhanced through active friction modulation. In this study, we propose a friction modulating slider that uses ultrasonic vibrations to achieve squeeze film levitation for friction control. This paper describes the design and evaluation of a friction-modulating slider for generating efficient locomotion in a two-slider prototype. The slider’s ability to modulate friction was tested through friction force experiments on a variety of surfaces, and its feasibility for locomotion was tested. The results show that the slider effectively reduced friction across different surfaces and enabled locomotion in the two-slider system. These findings highlight the potential of friction-modulating sliders to enhance the locomotion efficiency of sliding robotic devices, offering promising opportunities for various applications.

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.

Colonoscopy is a widely used endoscopic procedure to diagnose colorectal cancer (CRC) which is considered the fourth most common cancer in the US and the second most common cancer in Europe. Colonoscope, used in colonoscopy, consists of a thin flexible hollow tube that is inserted into the rectum of a person and propagated through the entire colon. The disadvantage of the current procedure is that the colonoscope has to be pushed from outside to move through the colon resulting in recurrent looping of the colonoscope due to buckling. Recurrent looping inflicts the risk of tissue damage and is responsible for approximately 90% of the pain experienced by patients during colonoscopy. Research was carried out to create self-propelling colonoscopes which would eliminate the force required to push the device from outside. Inspirations were taken from the locomotion of earthworms to develop self-propelling colonoscopes however, the device’s propulsion was hindered due to friction and low axial stiffness of the colon wall. In this study, a proof of concept for a self-propelled colonoscopic device inspired by the ovipositor of wasps was conducted which resulted in the development of a prototype. The prototype was tested in a colon-simulated environment and it was able to successfully propel through the prepared colon phantom after an initial manual run through the colon phantom. The requirement of an initial manual run was speculated to be due to the capillary adhesion and uneven oil spread in the colon phantom. The device had an average velocity of around 5.68 mm /s inside the colon phantom with an average efficiency of 72.5%. In the future, the prototype has to be tested in an actual colon to assess its functionality and evaluate the propulsion efficiency of the prototype in a real colon.

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.