A Review of Locomotion Systems for Capsule Endoscopy

Robotic wireless capsule endoscopy: recent advances and upcoming technologies

Wireless capsule endoscopy (WCE) offers a non-invasive evaluation of the digestive system, eliminating the need for sedation and the risks associated with conventional endoscopic procedures. Its significance lies in diagnosing gastrointestinal tissue irregularities, especially in the small intestine. However, existing commercial WCE devices face limitations, such as the absence of autonomous lesion detection and treatment capabilities. Recent advancements in micro-electromechanical fabrication and computational methods have led to extensive research in sophisticated technology integration into commercial capsule endoscopes, intending to supersede wired endoscopes. This Review discusses the future requirements for intelligent capsule robots, providing a comparative evaluation of various methods' merits and disadvantages, and highlighting recent developments in six technologies relevant to WCE. These include near-field wireless power transmission, magnetic field active drive, ultra-wideband/intrabody communication, hybrid localization, AI-based autonomous lesion detection, and magnetic-controlled diagnosis and treatment. Moreover, we explore the feasibility for future "capsule surgeons".

A review on model-based and model-free approaches to control soft actuators and their potentials in colonoscopy

Colorectal cancer (CRC) is the third most common cancer worldwide and responsible for approximately 1 million deaths annually. Early screening is essential to increase the chances of survival, and it can also reduce the cost of treatments for healthcare centres. Colonoscopy is the gold standard for CRC screening and treatment, but it has several drawbacks, including difficulty in manoeuvring the device, patient discomfort, and high cost. Soft endorobots, small and compliant devices thatcan reduce the force exerted on the colonic wall, offer a potential solution to these issues. However, controlling these soft robots is challenging due to their deformable materials and the limitations of mathematical models. In this Review, we discuss model-free and model-based approaches for controlling soft robots that can potentially be applied to endorobots for colonoscopy. We highlight the importance of selecting appropriate control methods based on various parameters, such as sensor and actuator solutions. This review aims to contribute to the development of smart control strategies for soft endorobots that can enhance the effectiveness and safety of robotics in colonoscopy. These strategies can be defined based on the available information about the robot and surrounding environment, control demands, mechanical design impact and characterization data based on calibration.

Villi Inspired Mechanical Interlocking for Intestinal Retentive Devices

Intestinal retentive devices have applications ranging from sustained oral drug delivery systems to indwelling ingestible medical devices. Current strategies to retain devices in the small intestine primarily focus on chemical anchoring using mucoadhesives or mechanical coupling using expandable devices or structures that pierce the intestinal epithelium. Here, the feasibility of intestinal retention using devices containing villi-inspired structures that mechanically interlock with natural villi of the small intestine is evaluated. First the viability of mechanical interlocking as an intestinal retention strategy is estimated by estimating the resistance to peristaltic shear between simulated natural villi and devices with various micropost geometries and parameters. Simulations are validated in vitro by fabricating micropost array patches via multistep replica molding and performing lap-shear tests to evaluate the interlocking performance of the fabricated microposts with artificial villi. Finally, the optimal material and design parameters of the patches that can successfully achieve retention in vivo are predicted. This study represents a proof-of-concept for the viability of micropost-villi mechanical interlocking strategy to develop nonpenetrative multifunctional intestinal retentive devices for the future.

Anchoring Mechanism for Capsule Endoscope: Mechanical Design, Fabrication and Experimental Evaluation

Capsule endoscopes are widely used to diagnose gut-related problems, but they are passive in nature and cannot actively move inside the gut. This paper details the design process and development of an anchoring mechanism and actuation system to hold a capsule in place within the small intestine. The design centres around the mechanical structure of the anchor that makes use of compliant Sarrus linkage legs, which extend to make contact with the intestine, holding the capsule in place. Three variants with 2 legs, 3 legs and 4 legs of the anchoring mechanism were tested using a shape memory alloy spring actuator (5 mm × ϕ 3.4 mm). The experiments determine that all the variants can anchor at the target site and resist peristaltic forces of 346 mN. The proposed design is well suited for an intestine with a diameter of 19 mm. The proposed design allows the capsule endoscopes to anchor at the target site for a better and more thorough examination of the targeted region. The proposed anchoring mechanism has the potential to become a vital apparatus for clinicians to use with capsule endoscopes in the future.

Recent developments in wireless capsule endoscopy imaging: Compression and summarization techniques

Wireless capsule endoscopy (WCE) can be viewed as an innovative technology introduced in the medical domain to directly visualize the digestive system using a battery-powered electronic capsule. It is considered a desirable substitute for conventional digestive tract diagnostic methods for a comfortable and painless inspection. Despite many benefits, WCE results in poor video quality due to low frame resolution and diagnostic accuracy. Many research groups have presented diversified, low-complexity compression techniques to economize battery power consumed in the radio-frequency transmission of the captured video, which allows for capturing the images at high resolution. Many vision-based computational methods have been developed to improve the diagnostic yield. These methods include approaches for automatically detecting abnormalities and reducing the amount of time needed for video analysis. Though various research works have been put forth in the WCE imaging field, there is still a wide gap between the existing techniques and the current needs. Hence, this article systematically reviews recent WCE video compression and summarization techniques. The review's objectives are as follows: First, to provide the details of the requirement, challenges and design percepts for the low complexity WCE video compressor. Second, to discuss the most recent compression methods, emphasizing simple distributed video coding methods. Next, to review the most recent summarization techniques and the significance of using deep neural networks. Further, this review aims to provide a quantitative analysis of the state-of-the-art methods along with their advantages and drawbacks. At last, to discuss existing problems and possible future directions for building a robust WCE imaging framework.

Capsule endoscopy - a non-invasive modality to investigate the GI tract: out with the old and in with the new?

INTRODUCTION

Capsule endoscopy has had significant development since it was introduced into the field of medicine in 2000. It is non-invasive, well tolerated, does not require sedation and is a first-line small bowel investigative modality. As it transits through the entire gastrointestinal (GI) tract, it has the potential to provide a pan-enteric examination.

AREAS COVERED

In this review we will discuss the new diagnostic modalities along with traditional methods which have been used for examination of the gastro intestinal (GI) tract. The main focus of this review will be on the use of capsule endoscopy for pan-enteric examination.

EXPERT OPINION

Capsule endoscopy is an accepted first-line investigation for the small bowel. Diagnostic sensitivity of the colon capsule is comparable to colonoscopy in controlled trials and is being evaluated in high-risk patients in routine clinical practice in national programs. Preliminary data suggest that a magnetic-controlled examination of the upper GI tract could be developed to enable a complete upper GI examination.

Capsule Endoscopy for Gastric Evaluation

Wireless capsule endoscopy was first developed to observe the small intestine. A small capsule can be swallowed and images of gastrointestinal tract are taken with natural movement of peristalsis. Application of capsule endoscopy for observing the stomach has also received much attention as a useful alternative to esophagogastroduodenoscopy, but anatomical characteristics of the stomach have demanded technical obstacles that need to be tackled: clear visualization and active movements that could be controlled. Different methods of controlling the capsule within stomach have been studied and magnetic manipulation is the only system that is currently used in clinical settings. Magnets within the capsule can be controlled with a hand-held magnet paddle, robotic arm, and electromagnetic coil system. Studies on healthy volunteers and patients with upper gastrointestinal symptoms have shown that it is a safe and effective alternative method of observing the stomach. This work reviews different magnetic locomotion systems that have been used for observation of the stomach as an emerging new application of wireless capsule endoscopy.

Capsule Endoscopy: Pitfalls and Approaches to Overcome

Capsule endoscopy of the gastrointestinal tract is an innovative technology that serves to replace conventional endoscopy. Wireless capsule endoscopy, which is mainly used for small bowel examination, has recently been used to examine the entire gastrointestinal tract. This method is promising for its usefulness and development potential and enhances convenience by reducing the side effects and discomfort that may occur during conventional endoscopy. However, capsule endoscopy has fundamental limitations, including passive movement via bowel peristalsis and space restriction. This article reviews the current scientific aspects of capsule endoscopy and discusses the pitfalls and approaches to overcome its limitations. This review includes the latest research results on the role and potential of capsule endoscopy as a non-invasive diagnostic and therapeutic device.

Autonomous navigation of a magnetic colonoscope using force sensing and a heuristic search algorithm

This paper presents an autonomous navigation system for cost-effective magnetic-assisted colonoscopy, employing force-based sensors, an actuator, a proportional-integrator controller and a real-time heuristic searching method. The force sensing system uses load cells installed between the robotic arm and external permanent magnets to derive attractive force data as the basis for real-time surgical safety monitoring and tracking information to navigate the disposable magnetic colonoscope. The average tracking accuracy on magnetic field navigator (MFN) platform in x-axis and y-axis are 1.14 ± 0.59 mm and 1.61 ± 0.45 mm, respectively, presented in mean error ± standard deviation. The average detectable radius of the tracking system is 15 cm. Three simulations of path planning algorithms are presented and the learning real-time A* (LRTA*) algorithm with our proposed directional heuristic evaluation design has the best performance. It takes 75 steps to complete the traveling in unknown synthetic colon map. By integrating the force-based sensing technology and LRTA* path planning algorithm, the average time required to complete autonomous navigation of a highly realistic colonoscopy training model on the MFN platform is 15 min 38 s and the intubation rate is 83.33%. All autonomous navigation experiments are completed without intervention by the operator.

Examination of Entire Gastrointestinal Tract: A Perspective of Mouth to Anus (M2A) Capsule Endoscopy

Capsule endoscopy (CE) is the only non-invasive diagnostic tool that enables the direct visualization of the gastrointestinal (GI) tract. Even though CE was initially developed for small-bowel investigation, its clinical application is expanding, and technological advances continue. The final iteration of CE will be a mouth to anus (M2A) capsule that investigates the entire GI tract by the ingestion of a single capsule. This narrative review describes the current developmental status of CE and discusses the possibility of realizing an M2A capsule and what needs to be overcome in the future.

Next-generation ingestible devices: sensing, locomotion and navigation

There is significant interest in exploring the human body's internal activities and measuring important parameters to understand, treat and diagnose the digestive system environment and related diseases. Wireless capsule endoscopy (WCE) is widely used for gastrointestinal (GI) tract exploration due to its effectiveness as it provides no pain and is totally tolerated by the patient. Current ingestible sensing technology provides a valuable diagnostic tool to establish a platform for monitoring the physiological and biological activities inside the human body. It is also used for visualizing the GI tract to observe abnormalities by recording the internal cavity while moving. However, the capsule endoscopy is still passive, and there is no successful locomotion method to control its mobility through the whole GI tract. Drug delivery, localization of abnormalities, cost reduction and time consumption are improvements that can be gained from having active ingestible WCEs. In this article, the current technological developments of ingestible devices including sensing, locomotion and navigation are discussed and compared. The main features required to implement next-generation active WCEs are explored. The methods are evaluated in terms of the most important features such as safety, velocity, complexity of design, control, and power consumption.

Intelligent automated drug administration and therapy: future of healthcare

In the twenty-first century, the collaboration of control engineering and the healthcare sector has matured to some extent; however, the future will have promising opportunities, vast applications, and some challenges. Due to advancements in processing speed, the closed-loop administration of drugs has gained popularity for critically ill patients in intensive care units and routine life such as personalized drug delivery or implantable therapeutic devices. For developing a closed-loop drug delivery system, the control system works with a group of technologies like sensors, micromachining, wireless technologies, and pharmaceuticals. Recently, the integration of artificial intelligence techniques such as fuzzy logic, neural network, and reinforcement learning with the closed-loop drug delivery systems has brought their applications closer to fully intelligent automatic healthcare systems. This review's main objectives are to discuss the current developments, possibilities, and future visions in closed-loop drug delivery systems, for providing treatment to patients suffering from chronic diseases. It summarizes the present insight of closed-loop drug delivery/therapy for diabetes, gastrointestinal tract disease, cancer, anesthesia administration, cardiac ailments, and neurological disorders, from a perspective to show the research in the area of control theory.

Design of a Legged and Clamper-Based Capsule Robot With Active Locomotion Function

This paper presents a legged and clamper-based capsule robot (CR) with active locomotion function. The CR utilizes the extension and contraction of the anchoring legs to expand the collapsed intestinal wall, crawl in the intestinal tract, and stand in large spaces such as the stomach and large intestine organs. The mechanical structure design, kinematic analysis, principle of locomotion, and force analysis of the CR are presented. The design concept and locomotion principles of the proposed CR are verified by a prototype with the diameter of 13 mm and length of 39 mm. Three experiments were conducted to test the locomotion performance of the proposed CR. In the experiments, the prototype successfully expands the collapsed phantom intestine, stands on the plane, and moves forward in transparent tube at a promising speed. Experimental results indicate that the CR has good locomotion capabilities.

A New Active Locomotion Capsule Endoscopy under Magnetic Control and Automated Reading Program

Capsule endoscopy (CE) is the first-line diagnostic modality for detecting small bowel lesions. CE is non-invasive and does not require sedation, but its movements cannot be controlled, it requires a long time for interpretation, and it has lower image quality compared to wired endoscopy. With the rapid advancement of technology, several methods to solve these problems have been developed. This article describes the ongoing developments regarding external CE locomotion using magnetic force, artificial intelligence-based interpretation, and image-enhancing technologies with the CE system.

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.

Modelling and Motion Analysis of a Pill-Sized Hybrid Capsule Robot

This paper presents a miniature hybrid capsule robot for minimally invasive in-vivo interventions such as capsule endoscopy within the GI (gastrointestinal) tract. It proposes new modes of operation for the hybrid robot namely hybrid mode and anchoring mode. The hybrid mode assists the robot to open an occlusion or to widen a narrowing. The anchoring mode enables the robot to stay in a specific place overcoming external disturbances (e.g. peristalsis) for a better and prolonged observation. The modelling of the legged, hybrid and anchoring modes are presented and analysed. Simulation results show robot propulsions in various modes. The hybrid capsule robot consisting four operating modes is more effective for the locomotion and observation within GI tract when compared to the locomotion consisting a single mean of locomotion as the hybrid robot can switch among the operating modes to suit the situation/task.

A Soft Pneumatic Inchworm Double balloon (SPID) for colonoscopy

The design of a smart robot for colonoscopy is challenging because of the limited available space, slippery internal surfaces, and tortuous 3D shape of the human colon. Locomotion forces applied by an endoscopic robot may damage the colonic wall and/or cause pain and discomfort to patients. This study reports a Soft Pneumatic Inchworm Double balloon (SPID) mini-robot for colonoscopy consisting of two balloons connected by a 3 degrees of freedom soft pneumatic actuator. SPID has an external diameter of 18 mm, a total length of 60 mm, and weighs 10 g. The balloons provide anchorage into the colonic wall for a bio-inspired inchworm locomotion. The proposed design reduces the pressure applied to the colonic wall and consequently pain and discomfort during the procedure. The mini-robot has been tested in a deformable plastic colon phantom of similar shape and dimensions to the human anatomy, exhibiting efficient locomotion by its ability to deform and negotiate flexures and bends. The mini-robot is made of elastomer and constructed from 3D printed components, hence with low production costs essential for a disposable device.

An Automatic Navigation and Pressure Monitoring for Guided Insertion Procedure

Navigation is an important feature needed for medical insertion procedures. It is required to guide the medical device in the right direction at the right time. Navigation techniques used in the Wireless Capsule Endoscopy and conventional endoscopy fields are based on image-guided systems that require a large amount of data to be transferred and processed computationally. These issues increase system complexity as well as the overall system and procedure costs. Moreover, these systems cannot provide the required information in dark or liquid areas. To improve the medical internal inspections capabilities, we present a pressure direction measurement system that can be implemented for a capsule endoscope; ordinary endoscopy; and any other insertion procedure where navigation and safety are required. The system can operate in dark and liquid areas because no visualization is required. The system consists of a pressure sensor placed on a semi-hemisphere on top of the steering device to detect azimuth and polar angle variation according to the direction at any differentiable path.

Investigation of Current Control for a New Bi-directional Linear Capsule Robot

In this paper, a bi-directional linear capsule robot (capsulbot) for potential applications in Gastrointestinal (GI) tract inside human body is studied. Compared with the conventional endoscope limited by its poor locomotion and steering capabilities, active locomotion actuator will play an important role in the diagnosis of narrow organ tract of the human body in the future. This paper studies a new simple-structured actuator that can realize bi-directional linear motion by properly controlling the supplied current profile. It is demonstrated that the linear motion of the new capsulbot is affected by three main factors: current waveform, current duty ratio, and current amplitude. The optimized current profile that can maximize the capsulbot displacement is verified experimentally on a prototype capsulbot.

Nano-plasmonics and electronics co-integration in CMOS enabling a pill-sized multiplexed fluorescence microarray system

The ultra-miniaturization of massively multiplexed fluorescence-based bio-molecular sensing systems for proteins and nucleic acids into a chip-scale form, small enough to fit inside a pill (∼ 0.1cm3), can revolutionize sensing modalities in-vitro and in-vivo. Prior miniaturization techniques have been limited to focusing on traditional optical components (multiple filter sets, lenses, photo-detectors, etc.) arranged in new packaging systems. Here, we report a method that eliminates all external optics and miniaturizes an entire multiplexed fluorescence system into a 2 × 1 mm2 chip through co-integration for the first time of massively scalable nano-plasmonic multi-functional optical elements and electronic processing circuitry realized in an industry standard complementary-metal-oxide semiconductor (CMOS) foundry process with absolutely 'no change' in fabrication or processing. The implemented nano-waveguide based filters operating in the visible and near-IR realized with the embedded sub-wavelength multi-layer copper-based electronic interconnects inside the chip show for the first time a sub-wavelength surface plasmon polariton mode inside CMOS. This is the principle behind the angle-insensitive nature of the filtering that operates in the presence of uncollimated and scattering environments, enabling the first optics-free 96-sensor CMOS fluorescence sensing system. The chip demonstrates the surface sensitivity of zeptomoles of quantum dot-based labels, and volume sensitivities of ∼ 100 fM for nucleic acids and ∼ 5 pM for proteins that are comparable to, if not better, than commercial fluorescence readers. The ability to integrate multi-functional nano-optical structures in a commercial CMOS process, along with all the complex electronics, can have a transformative impact and enable a new class of miniaturized and scalable chip-sized optical sensors.

Low-Power, High Data-Rate Digital Capsule Endoscopy Using Human Body Communication

A technology for low-power high data-rate digital capsule endoscopy with human body communication (CEHBC) is presented in this paper. To transfer the image data stably with low power consumption, the proposed system uses three major schemes: Frequency selective digital transmission (FSDT) modulation with HBC, the use of an algorithm to select electrode pairs, and the LineSync algorithm. The FSDT modulation supports high-data rate transmission and prevents the signal attenuation effect. The selection algorithm of the electrode pair finds the best receiving channel. The LineSync algorithm synchronizes the data and compensates for data polarity during the long data transmission section between the capsule endoscope and the receiver. Because all the major functional blocks of the CEHBC transmitter can be implemented as digital logics, they can be easily fabricated using the field programmable gate array (FPGA). Moreover, this CEHBC transmitter can achieve low power-consumption and can support a relatively high data rate in spite of using its clock a few tens of MHz slower. The proposed CEHBC-TXD is the digital portion of the CEHBC transmitter that provides low-power (3.7 mW) and high data-rate (6 Mbps) performance while it supports a high-resolution image (480 × 480 byte) at 3.13 fps.

Digitalized Human Organoid for Wireless Phenotyping

Radio frequency identification (RFID) is a cost-effective and durable method to trace and track individual objects in multiple contexts by wirelessly providing digital signals; RFID is thus widely used in many fields. Here, we implement this concept to biological tissues by producing a compact RFID chip-incorporated organoid (RiO). The 0.4 mm RFID chips are reproducibly integrated inside the self-assembling organoids from 10 different induced pluripotent stem cell (iPSC) lines from healthy and diseased donors. We use the digitalized RiO to conduct a phenotypic screen on a pool of RiO, followed by detection of each specific donor in situ. Our proof-of-principle experiments demonstrated that a severely steatotic phenotype could be identified by RFID chip reading and was specific to a genetic disorder of steatohepatitis. Given evolving advancements surrounding RFID technology, the digitalization principle outlined here will expand organoid medicine potential toward drug development, precision medicine, and transplant applications.

A Locomotion Control Platform With Dynamic Electromagnetic Field for Active Capsule Endoscopy

Conventional radiological and endoscopic techniques utilizing long tubes were ineffective in visualizing the small bowel mucosa until the development of wireless capsule endoscopy (WCE). WCE is a revolutionary endoscopic technology that can diagnose the complete gastrointestinal tract. However, the existing capsule technologies are passive, and thus they cannot be navigated to or held in a specific location. The design of an active capsule will present the opportunity to move and stop a device at any targeted locations leading to numerous medical applications such as drug delivery or collecting tissue samples for examinations in the laboratory. This paper implements a new locomotion methodology for WCE systems using an electromagnetic platform. The platform produces a dynamic electromagnetic field to control the motion of the capsule. The strength and the direction of the electromagnetic field that is generated by the platform are continuously adjusted in order to maintain the equilibrium state during the capsule movement. We present the detailed design of the proposed platform with an experimental setup with polyvinyl chloride tubes and ex vivo to demonstrate the performance of the capsule motion.

Medical capsule robots: A renaissance for diagnostics, drug delivery and surgical treatment

The advancements in electronics and the progress in nanotechnology have resulted in path breaking development that will transform the way diagnosis and treatment are carried out currently. This development is Medical Capsule Robots, which has emerged from the science fiction idea of robots travelling inside the body to diagnose and cure disorders. The first marketed capsule robot was a capsule endoscope developed to capture images of the gastrointestinal tract. Today, varieties of capsule endoscopes are available in the market. They are slightly larger than regular oral capsules, made up of a biocompatible case and have electronic circuitry and mechanisms to capture and transmit images. In addition, robots with diagnostic features such as in vivo body temperature detection and pH monitoring have also been launched in the market. However, a multi-functional unit that will diagnose and cure diseases inside the body has not yet been realized. A remote controlled capsule that will undertake drug delivery and surgical treatment has not been successfully launched in the market. High cost, inadequate power supply, lack of control over drug release, limited space for drug storage on the capsule, inadequate safety and no mechanisms for active locomotion and anchoring have prevented their entry in the market. The capsule robots can revolutionize the current way of diagnosis and treatment. This paper discusses in detail the applications of medical capsule robots in diagnostics, drug delivery and surgical treatment. In diagnostics, detailed analysis has been presented on wireless capsule endoscopes, issues associated with the marketed versions and their corresponding solutions in literature. Moreover, an assessment has been made of the existing state of remote controlled capsules for targeted drug delivery and surgical treatment and their future impact is predicted. Besides the need for multi-functional capsule robots and the areas for further research have also been highlighted.

A wireless capsule endoscopy steering mechanism using magnetic field platform

In this paper, a new steering mechanism for wireless capsule devices is presented. The proposed system consists of a platform generating a magnetic field to direct and control the motion of a capsule. The platform contains an upper and a lower set of electromagnets. A permanent magnet is implanted inside the capsule to initiate the movement, which is set by the magnetic field delivered by the electromagnets. The total magnetic field at the capsule's location is the sum of the contributions of each electromagnet. An experimental setup has been designed for testing and comparing between the performance of the capsule mobility in practice and simulations.

Established and emerging methods for assessment of small and large intestinal motility

BACKGROUND

Gastrointestinal symptoms are common in the general population and may originate from disturbances in gut motility. However, fundamental mechanistic understanding of motility remains inadequate, especially of the less accessible regions of the small bowel and colon. Hence, refinement and validation of objective methods to evaluate motility of the whole gut is important. Such techniques may be applied in clinical settings as diagnostic tools, in research to elucidate underlying mechanisms of diseases, and to evaluate how the gut responds to various drugs. A wide array of such methods exists; however, a limited number are used universally due to drawbacks like radiation exposure, lack of standardization, and difficulties interpreting data. In recent years, several new methods such as the 3D-Transit system and magnetic resonance imaging assessments on small bowel and colonic motility have emerged, with the advantages that they are less invasive, use no radiation, and provide much more detailed information.

PURPOSE

This review outlines well-established and emerging methods to evaluate small bowel and colonic motility in clinical settings and in research. The latter include the 3D-Transit system, magnetic resonance imaging assessments, and high-resolution manometry. Procedures, indications, and the relative strengths and weaknesses of each method are summarized.

Magnetically guided capsule endoscopy

Wireless capsule endoscopy (WCE) is a powerful tool for medical screening and diagnosis, where a small capsule is swallowed and moved by means of natural peristalsis and gravity through the human gastrointestinal (GI) tract. The camera-integrated capsule allows for visualization of the small intestine, a region which was previously inaccessible to classical flexible endoscopy. As a diagnostic tool, it allows to localize the sources of bleedings in the middle part of the gastrointestinal tract and to identify diseases, such as inflammatory bowel disease (Crohn's disease), polyposis syndrome, and tumors. The screening and diagnostic efficacy of the WCE, especially in the stomach region, is hampered by a variety of technical challenges like the lack of active capsular position and orientation control. Therapeutic functionality is absent in most commercial capsules, due to constraints in capsular volume and energy storage. The possibility of using body-exogenous magnetic fields to guide, orient, power, and operate the capsule and its mechanisms has led to increasing research in Magnetically Guided Capsule Endoscopy (MGCE). This work shortly reviews the history and state-of-art in WCE technology. It highlights the magnetic technologies for advancing diagnostic and therapeutic functionalities of WCE. Not restricting itself to the GI tract, the review further investigates the technological developments in magnetically guided microrobots that can navigate through the various air- and fluid-filled lumina and cavities in the body for minimally invasive medicine.

Improving resolution of robotic capsule locomotion using dynamic electromagnetic field

This paper describes a new method to control the motion of swallowable wireless capsule endoscopy devices. A dynamic magnetic field produced by a set of external magnetic coils is used to manage the locomotion of the capsule. A permanent magnet is embedded into the capsule in order to manipulate the capsule by changing the external magnetic field strength for each specific position. The dynamic magnetic field is externally controlled to reach and maintain the equilibrium state for holding the capsule in a specific location. This is achieved by keeping the net force of magnetic fields zero. To start the mobility, the magnetic field from one of the external field sources will be reduced for a certain amount of time by sending an OFF-pulse (a current source). The required forces and the pulses are controlled by a specific algorithm to control the step size of the movement in order to achieve precise motion at any chosen velocity. The proposed method is designed to provide a precise motion control with a system extremely low in complexity.