A Review of Locomotion Systems for Capsule Endoscopy

Wireless capsule endoscopy for gastrointestinal (GI) tract is a modern technology that has the potential to replace conventional endoscopy techniques. Capsule endoscopy is a pill-shaped device embedded with a camera, a coin battery, and a data transfer. Without a locomotion system, this capsule endoscopy can only passively travel inside the GI tract via natural peristalsis, thus causing several disadvantages such as inability to control and stop, and risk of capsule retention. Therefore, a locomotion system needs to be added to optimize the current capsule endoscopy. This review summarizes the state-of-the-art locomotion methods along with the desired locomotion features such as size, speed, power, and temperature and compares the properties of different methods. In addition, properties and motility mechanisms of the GI tract are described. The main purpose of this review is to understand the features of GI tract and diverse locomotion methods in order to create a future capsule endoscopy compatible with GI tract properties

A Development Study of a New Bi-directional Solenoid Actuator for Active Locomotion Capsule Robots

A new bi-directional, simple-structured solenoid actuator for active locomotion capsule robots (CRs) is investigated in this paper. This active actuator consists of two permanent magnets (PMs) attached to the two ends of the capsule body and a vibration inner mass formed by a solenoidal coil with an iron core. The proposed CR, designed as a sealed structure without external legs, wheels, or caterpillars, can achieve both forward and backward motions driven by the internal collision force. This new design concept has been successfully confirmed on a capsule prototype. The measured displacements show that its movement can be easily controlled by changing the supplied current amplitude and frequency of the solenoid actuator. To validate the new bi-directional CR prototype, various experimental as well as finite element analysis results are presented in this paper

Capsule endoscopy of the future: What's on the horizon?

Capsule endoscopes have evolved from passively moving diagnostic devices to actively moving systems with potential therapeutic capability. In this review, we will discuss the state of the art, define the current shortcomings of capsule endoscopy, and address research areas that aim to overcome said shortcomings. Developments in capsule mobility schemes are emphasized in this text, with magnetic actuation being the most promising endeavor. Research groups are working to integrate sensor data and fuse it with robotic control to outperform today's standard invasive procedures, but in a less intrusive manner. With recent advances in areas such as mobility, drug delivery, and therapeutics, we foresee a translation of interventional capsule technology from the bench-top to the clinical setting within the next 10 years

Swallowable Wireless Capsule Endoscopy: Progress and Technical Challenges

Wireless capsule endoscopy (WCE) offers a feasible noninvasive way to detect the whole gastrointestinal (GI) tract and revolutionizes the diagnosis technology. However, compared with wired endoscopies, the limited working time, the low frame rate, and the low image resolution limit the wider application. The progress of this new technology is reviewed in this paper, and the evolution tendencies are analyzed to be high image resolution, high frame rate, and long working time. Unfortunately, the power supply of capsule endoscope (CE) is the bottleneck. Wireless power transmission (WPT) is the promising solution to this problem, but is also the technical challenge. Active CE is another tendency and will be the next geneion of the WCE. Nevertheless, it will not come true shortly, unless the practical locomotion mechanism of the active CE in GI tract is achieved. The locomotion mechanism is the other technical challenge, besides the challenge of WPT. The progress about the WPT and the active capsule technology is reviewed

Doctor of Philosophy

dissertationClosed-loop control of wireless capsule endoscopes is an active area of research because it would drastically improve screening of the gastrointestinal tract. Traditional endoscopic procedures are unable to view the entire gastrointestinal tract and current commercial wireless capsule endoscopes are limited in their effectiveness due to their passive nature. This dissertation advances the field of active capsule endoscopy by developing methods to localize the full six-degree-of-freedom (6-DOF) pose of a screw-type magnetic capsule while it is being propelled through a lumen (such as the small intestines) using an external rotating magnetic dipole. The same external magnetic dipole is utilized for both propulsion and localization. Hardware was designed and constructed to enable testing of the magnetic localization and propulsion methods, including a robotic end-effector used as the external actuator magnet, and a prototype capsule embedded with Hall-effect sensors. Due to the use of a rotating magnetic field for propulsion, at any given time, the capsule can be in one of three regimes: synchronously rotating with the applied field, in "step-out" where it is free to move but the external field is rotating too quickly for the capsule to remain synchronously rotating, or completely stationary. We show that it is only necessary to distinguish whether or not the capsule is synchronously rotating (i.e., a single localization method can be used for a capsule in either the step-out or stationary regimes). Two magnetic localization methods are developed. The first uses nonlinear least squares to estimate the capsule's pose when it has no (or approximately no) net motion (e.g., to find the initial capsule pose or when it is stuck in an intestinal fold). The second method estimates the 6-DOF capsule pose as it synchronously rotates with the applied magnetic field using a square-root variant of the Unscented Kalman filter. A simple process model is adopted that restricts the capsule's movement to translation along and rotation about its principle axis. The capsule is actively propelled forward or backward, but it is not actively steered, rather, steering is provided by the lumen. The propulsion parameters that transform magnetic force and torque to the capsule's spatial velocity and angular velocity are estimated with an additional square-root Unscented Kalman filter to enable the capsule to navigate heterogeneous environments such as the small intestines. An optimized localization-propulsion system is described using the two localization algorithms and prior work in screw-type magnetic capsule propulsion with a single rotating dipole field. The capsule's regime is determined and the corresponding localization method is employed. Based on the capsule's estimated pose and the current estimates of its propulsion parameters, the actuator magnet's pose relative to the capsule is optimized to maximize the capsule's forward propulsion. Using this system, our prototype magnetic capsule successfully completed U-shaped and S-shaped trajectories in fresh bovine intestines with an average forward velocity of 5.5mm/s and 3.5 mm/s, respectively. At this rate it would take approximately 18-30 minutes to traverse the 6 meters of a typical human small intestine

Doctor of Philosophy

dissertationThis dissertation presents results documenting advancements on the control of untethered magnetic devices, such as magnetic \microrobots" and magnetically actuated capsuleendoscopes, motivated by problems in minimally invasive medicine. This dissertationfocuses on applying rotating magnetic elds for magnetic manipulation. The contributions include advancements in the way that helical microswimmers (devices that mimicthe propulsion of bacterial agella) are controlled in the presence of gravitational forces, advancements in ways that groups of untethered magnetic devices can be dierentiated and semi-independently controlled, advancements in the way that untethered magnetic device can be controlled with a single rotating permanent magnet, and an improved understanding in the nature of the magnetic force applied to an untethered device by a rotating magnet

Soft hybrid intrinsically motile robot for wireless small bowel enteroscopy

BACKGROUND: Difficulties in establishing diagnosis of small bowel (SB) disorders, prevented their effective treatment. This problem was largely resolved by wireless capsule endoscopy (WCE), which has since become the first line investigation for suspected SB disorders. Several types of WCE pills are now used in clinical practice, despite their limitations and complications. WCE pills are large, rigid and immotile capsules. When swallowed, they provide SB enteroscopy downloaded to a data logger carried by the patient. Most of the complications of WCEs result from lack of intrinsic locomotion: incomplete examination, capsule retention and impaction within strictures. In addition, the rigid nature and size of current generation of WCE pills is accompanied by 0.1% inability to swallow the pill by patients with normal esophageal motility. METHODS: The aim of this communication is to describe the initial prototype, P(1), which is thinner and slightly longer than the current generation of WCEs. In addition, it exhibits intrinsic active locomotion, produced by vibrating silicon legs. These generate a controlled-skid locomotion on the small bowel mucosal surface, rendered slippery by surface mucus and intraluminal surfactant bile salts. We demonstrate the mechanism responsible for the active locomotion of P(1), which we consider translatable into a working prototype, suitable for further R&D for eventual clinical translation. RESULTS: The shape and attachment of the rubber vibrating legs to vibrating actuators, have been designed specifically to produce a tight clockwise circular motion. When inserted inside a circular tube in vitro of equivalent diameter to human small intestine, the intrinsic circular clockwise motion of P(1) translates into a linear locomotion by the constraints imposed by the surrounding circular walls of SB and rest of the gastrointestinal tract. This design ensures device stability during transit, essential for imaging and targeting lesions encountered during the enteroscopy. We preformed two experiments: (i) transit of P(1) through a phantom consisting of a segment of PVC tube placed on a horizontal surface and (ii) transit through a transparent slippery nylon sleeve insufflated with air. In the PVC tube, its transit rate averages 15.6 mm/s, which is too fast for endoscopy: whereas inside the very slippery nylon sleeve insufflated with air, the average transit rate of P(1) is reduced to 5.9 mm/s, i.e., ideal for inspection endoscopy. CONCLUSIONS: These in-vitro experiments indicate that the P(1) hybrid soft robot prototype has the potential specifically for clinical translation for SB enteroscopy. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00464-021-09007-7

Design of optimised linear quadratic regulator for capsule endoscopes based on artificial bee colony tuning algorithm

Wireless Capsule Endoscope (WCE) is a new medical device that can be used for examining the whole digestive tract if effectively actuated. In this paper, a new three-coil actuator is proposed for the capsule endoscope navigation system. The proposed system, which is based on the currentcontrolled magnetic levitation concept, utilises a small permanent magnet within the capsule body and an arrangement of controlled electromagnet actuator placed on a movable frame. The dynamics of the proposed control system is modelled mathematically and then formulated in state space form. In this research, the Linear Quadratic Regulator (LQR) technique is used for designing a 3DOF controller for the capsule actuation system. Artificial Bee Colony (ABC) tuning algorithm is used for obtaining optimum values for controller gain parameters. The optimised LQR controller is simulated by using the Matlab/Simulink tool, and its performance is then evaluated based on the stability and control effort parameters to validate the proposed system. Finally, the simulation results suggest that the LQR controller based on the ABC optimisation method can be adopted to synthesise an effective capsule actuation system

Origami inspired design for capsule endoscope to retrograde using intestinal peristalsis

Capsule endoscopy has gained a lot of attention in the medical field in the recent past as an effective way of investigating unusual symptoms experienced in places such as esophagus, stomach, small intestine and colon. However, motion control of the capsule endoscope is challenging and often requires a power source and miniature actuators. To address these issues, we present a novel origami inspired structure as an attachment to the capsule endoscope. The proposed origami structure utilizes the wave generated by peristalsis of the intestine to move it forward and backward. When the origami structure is folded, the capsule endoscope is propelled forward by intestinal peristalsis. When the origami structure is unfolded, the intestinal peristalsis squeezes the origami structure to drive the capsule endoscope to move in the opposite direction. Therefore, folding and unfolding of the proposed origami structure would allow to control the movement direction of the capsule endoscope. In this paper, we present the design, simulations and experimental validation of the proposed origami structure