Capsule Robot Research Articles

Active Capsule Endoscope Robot: Current Status and Future Perspectives

Background: China is a big country with a vast territory, in which gastropathy has become a common high-incidence disease in daily life. Gastroscopy is an important means of diagnosis of gastropathy, but the use of a gastroscope causes a lot of pain to patients. A cable-free, non-invasive and painless diagnosis and treatment tool, an active capsule endoscope robot, can solve this problem very well. Capsule robot has become a new development hotspot. Objective: The study aims to provide an overview of the active endoscope capsule robot and introduce its classification, characteristics and development. Method: This paper summarizes various scientific research achievements of the active endoscope capsule robot. The structural characteristics, advantages and disadvantages of various active endoscope capsule robots are introduced. Results: The active endoscope capsule robot has been analyzed and compared to other models. Its typical characteristics have been summarized. The main problems in its development are analyzed, its development trend is prospected, and the research status and future of active endoscope capsule robot are discussed. Conclusion: The active capsule robot is classified into two categories: bionic and non-bionic. The analysis shows that the capsule robot is an effective and safe initiative and has a very broad application prospect for various gastrointestinal tests compared to gastroscope, and helps alleviate the pain of patients.

External and Internal Sensor Fusion Based Localization Strategy for 6-DOF Pose Estimation of a Magnetic Capsule Robot

This paper introduces a novel localization approach for active capsule endoscopy that, for the first time, combines external magnetic field sensing and internal inertial sensing to realize 6-DOF pose estimation of a magnetic capsule robot. It utilizes an inertial measurement unit embedded in the capsule with an external magnetic sensor array to estimate the 6-DOF pose of the capsule, which does not require complicated structures of the capsule and the actuator or the implementation of specific motions of the magnets, and can achieve accurate and real-time localization of the capsule in a large workspace. We formulate the localization model and analyze the singularities of the method, and present the design approach to determine the configuration of the localization system for efficient and accurate localization in a 0.5 × 0.5 × 0.2 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> workspace. Simulation and real-wold experiments are conducted to validate the effectiveness of the proposed localization strategy. Our results show that the proposed method can achieve a localization accuracy of 5.35 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 2.89 mm and 1.46 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 1.09 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> in position and orientation in the real-time tracking task at an update rate of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$60 \,\mathrm{Hz}$</tex-math></inline-formula> . The presented method can be integrated with any magnetic actuation method to achieve closed-loop control of a magnetic capsule robot in the human body.

A Magnetically Actuated Novel Robotic Capsule for Site-Specific Drug Delivery Inside the Gastrointestinal Tract

In this study, a novel magnetically actuated robotic capsule (patent-filed, Alici and Zhou, 2019) is proposed for site-specific drug delivery inside the gastrointestinal tract. Retractable needles are equipped into the capsule-like robot to inject the drug directly into intended tissues, which will contribute to the full and fast absorption of the medication and consequently increase the efficacy of drug delivery. The needle is concealed inside the capsule initially and can be actively protruded and retracted by a magnetic membrane. A second magnetic membrane is employed to discharge the drug out of the reservoir and inject it into the targeted tissue through the needle. Besides active drug releasing, the robotic capsule is able to perform active locomotion controlled by an external magnet wirelessly. Theoretical and experimental analyses were conducted to characterize the magnetic membranes for the selections of these batteries-less soft actuators for wireless in-body drug injection. Both locomotion and drug injection tests were successfully performed with the prototypes inside the samples of the porcine small intestine, which validated the feasibility of the proposed drug delivery system.

Design, Fabrication, and Testing of a Novel Ferrofluid Soft Capsule Robot

This article proposes a ferrofluid soft capsule robot (FSCR) with magnetic actuation for diagnostic and therapeutic medical applications inside the human stomach. A composite shell consisted of ferrofluid, permanent magnet rings, and soft elastomer is developed for the FSCR, which is actuated remotely by an external permanent magnet. The proposed FSCR presents two novel characteristics. First, the composite shell not only has a soft outer surface that reduces damage to contact tissue but also an improved magnetic circuit with a combination of the ferrofluid and permanent magnet rings makes the locomotion of the device more controllable and secure. Second, the FSCR is equipped with a specific oscillation module that enables advanced functions such as drug-releasing. Detailed structure design and fabrication of the FSCR are presented in this study. The surface rolling locomotion of the FSCR is modeled and evaluated by numerical simulations, as well as the drug-releasing function. In order to verify the simulation result, an FSCR prototype is manufactured to perform experimental validation. The analysis result demonstrates the feasibility and efficiency of the proposed FSCR for drug releasing inside a printed human stomach model.

Design and analysis of a wireless power transfer system for capsule robot using an optimised planar square spiral transmitting coil pair.

The wireless power transfer system (WPTS) is a promising way to continuously provide efficient and stable power for gastrointestinal capsule robots with active movement ability. The proposed WPTS using an optimised planar square spiral transmitting coil pair with space-saving structure can flexibly adjust the distance between the coils according to the patient's condition, and thus has better applicability. To improve power transfer efficiency and uniformity of the generated magnetic field, design parameters are discussed and optimised based on the analytical calculation and simulation analysis. The power demand can be guaranteed with spacing distance of 350-500mm and the peak received power of 1124mW with a remarkable transfer efficiency of 7.8% can be obtained when the spacing reaches the minimum. The human electromagnetic exposure safety in different situations is also discussed and verified. The WPTS can provide power for capsule robots safely and efficiently.

Medical Capsule Robots: An Overview on wireless capsule endoscope.

Capsule endoscopy (CE) has improved the diagnosis and treatment of the small bowel providing a non-invasive, well tolerated method of as it should be visualizing the upper and lower gastrointestinal tract. The development of Medical Capsule Robots, which has emerged from the science fiction idea of robots touring within the body to diagnose and cure issues. The first ever introduced capsule robot was a pill or capsule endoscope evolved to seize pics of the gastrointestinal tract. Today, varieties of capsule endoscopes are available and are expected to hit the market soon. They are barely large than ordinary oral dosage forms such as tablets or capsules, made of a biocompatible case and have digital circuitry and mechanisms to seize and transmit images.15 years ago, capsule endoscopy (CE) has turn out to be the primary-line investigation system in some small bowel pathologies and scientific practices. The first marketed capsule robotic was a capsule endoscope in general evolved to seize only the pictures of the gastrointestinal tract however Later, these have been advanced to be used as a device to construct micron and sub-micron sized drug shipping structures for target shipping and treatment.Technology is swiftly progressing, assisting in the broadening and improving the benefits and applications of capsule endoscopy.

Autonomous Magnetic Navigation Framework for Active Wireless Capsule Endoscopy Inspired by Conventional Colonoscopy Procedures

In recent years, simultaneous magnetic actuation and localization (SMAL) for active wireless capsule endoscopy (WCE) has been intensively studied to improve the efficiency and accuracy of gastrointestinal (GI) examination using WCE. In this letter, we draw inspiration from the conventional colonoscopy procedures and propose an autonomous navigation framework for active WCE based on SMAL technologies, in order to realize efficient and accurate navigation of a robotic capsule endoscope in unknown tubular environments (e.g., intestines) with minimal user effort. First, the capsule is actuated to explore the unknown tubular environment using an automatic propulsion algorithm, and a viable path to represent the environment is generated. Then, the capsule is navigated towards any user-selected point on the trajectory using a trajectory following algorithm, to allow accurate and repeated inspections of suspicious lesions. We implement the navigation framework on a robotic system incorporated with advanced SMAL algorithms, and validate it in the navigation experiments in various tubular environments including phantoms and ex-vivo pig colons. Our results demonstrate that the proposed framework can effectively navigate the capsule in unknown, complex tubular environments with a satisfactory accuracy, repeatability and efficiency.

Preliminary study of a novel capsule robot with spring-connected legs

This paper proposes a novel capsule robot (CR) with spring-connected legs for potential usage in the gastrointestinal (GI) tract. The proposed CR has a set of six legs and is actuated by a micromotor through internal mechanisms. Every two adjacent legs are connected by a spring. The leg opening-folding movement, together with the spring stretching-contraction motion, may be employed to distend the GI tract, carry out drug delivery or perform biopsy. The relationship between the driving force required by the spring set and the spring length was carefully calculated and simulated. This relationship was also measured by an NI data acquisition system. The calculated and measured data showed good accordance with each other. In addition, the driving force from the micromotor was calculated. Both the calculations and the CR experiments demonstrated that the internal motor could provide sufficient force on the springs.

Speed optimisation and reliability analysis of a self-propelled capsule robot moving in an uncertain frictional environment

The dynamics of a self-propelled capsule robot for small-bowel endoscopy driven by its internal vibro-impact excitation is studied in this paper. Due to its complex anatomy, the frictional environment in the small bowel is uncertain, so this work aims to maintain the progression of the robot at a desired velocity in the presence of such an uncertainty by using a new optimisation method. The optimisation method consists of the Six Sigma and the Multi-Island Genetic algorithms, and its reliability analysis is carried out with the consideration of parametric and environmental uncertainties by using the Monte Carlo algorithm. In total, five different motions of the capsule, including fast, slow, forward, backward and hovering, are optimised. Extensive numerical studies show that the five desired motions can be fulfilled by various combinations of system and control parameters. Experimental verification is also carried out using a capsule prototype to demonstrate the efficacy of the proposed method. A mismatch between the numerical optimisation and the experimental results for the backward motion of the prototype was observed. However, optimisations for forward and hovering motions show good agreements with experimental observations. Potentially, the proposed approach can be used for optimising various progressive robots in different scales with multiple control objectives and constraints.

Design and implementation of a highly integrated dual hemisphere capsule robot.

To achieve cancer screening in any appointed position in 3D regions of the gastrointestinal (GI) tract such as esophagus, stomach and colon, a highly integrated dual hemisphere capsule robot (DHCR) with a novel three-layer nested structure is proposed. Based on tracking effect, in which the robotic axis is likely to be approximately coincident with the orientation of thespace universal rotating magnetic field (SURMF) using the gyroscope dynamic balance, the dual hemisphere structure realizes the observation at a fixed-point in the passive mode and the rolling locomotion in the active mode by the dynamic posture control of the SURMF manipulation. The image acquisition module, wireless transmission module and driving actuator are tuned in a spherical structure, making the DHCR more compact and less invasive. To verify the maneuverability of the innovative DHCR both for observation at a fixed-point and navigation in curved intestine by aid of image, experiments are conducted in the simulated GI tract environment. The results show that the DHCR achieves effective conversion between posture adjustment and rolling locomotion, which lays a foundation for all-over inspection and medical operation inside 3D regions of the GI tract of human body.

Pose tracking method using magnetic excitations with frequency division for robotic endoscopic capsules.

The poses of robotic endoscopic capsules are indispensable for further follow-up examinations, potential targeted drug delivery, and closed-loop controlling of active locomotion. A novel tracking method using the multiple magnetic excitations with frequency division has been investigated. The multiple excitation coils can simultaneously work at different frequency to improve real-time tracking. A novel model between the magnetic flux density and the capsule's pose has been derived, which shows a nonlinear equation group with multiple local extremum. Then, a Back-Propagation (BP) neural network algorithm combined with the mother wavelet is investigated to solve the pose. To reduce the volume and power consumption, the wireless magnetic sensing module uses digital signal processing as the core framework, which is beneficial to be miniaturized to integrate with the capsule. The functional prototype of the tracking system has been developed, which consists of a wireless magnetic sensing module mounted in the capsule, a magnetic excitation module with frequency division, a wireless receiver and data interface, an excitation coil array and a platform for pose solving. The experimental results show that the mean errors are 0.0098m in x-component, 0.0122m in y-component, 0.0077m in z-component, 0.187rad in α-component and 0.161rad in β-component, respectively. The real-time performance of the tracking system is improved.

A Novel Biopsy Capsule Robot Based on High-Speed Cutting Tissue.

The capsule robot (CR) is a promising endoscopic method in gastrointestinal diagnosis because of its low discomfort to users. Most CRs are used to acquire image information only and lack the ability to collect samples. Although some biopsy capsule robots (BCRs) have been developed, it remains challenging to acquire the intestinal tissue while avoiding tearing and adhesion due to the flexibility of colonic tissue. In this study, we develop a BCR with a novel sampling strategy in which soft tissue is scratched with sharp blades rotating at high speed to avoid tissue tearing. In the BCR design, a spiral spring with prestored energy is used to release high energy within a short period of time, which is difficult for a motor or magnet to perform within a small capacity installation space. The energy of the tightened spiral spring is transmitted to drive sharp blades to rotate quickly via a designed gear mechanism. To guarantee reliable sampling, a Bowden cable is used to transmit the user's manipulation to trigger the rotation of the blades, and the triggering force transmitted by the cable can be monitored in real time by a force sensor installed at the manipulating end. A prototype of the proposed BCR is designed and fabricated, and its performance is tested through in vitro experiments. The results show that the proposed BCR is effective and the size of its acquired samples satisfies clinical requirements.

Magnetically Actuated Capsule Robots: A Review

Capsule endoscopy is a procedure that uses a tiny wireless camera inside a capsule endoscope to take pictures of patient&#x2019;s gastrointestinal tract for diagnosis. Gastrointestinal examination has been revolutionized by capsule endoscope for its simplicity and non-invasiveness. However, at this stage, the capsule endoscope has weak controllable locomotion capability, and does not have extended functions such as biopsy, localization, and therapeutics, which has become the main obstacle to expanding its application. Using an external magnetic field to actuate the capsule endoscope has the advantages of simple response structure inside the capsule and remote energy supply, which can expand the above-mentioned functions of the capsule endoscope and develop into a multifunctional capsule robot. This paper analyzes two types of magnetic actuation systems for magnetically actuated capsule robots, discusses the research on the functions of magnetically actuated capsule robots in active locomotion, anchoring, biopsy, localization, therapeutics, wireless power supply, and multi-capsule robot collaboration, and points out the existing problems and future development directions of magnetically actuated capsule robots.

Research on Rolling Locomotion Dynamics Characteristics of a Dual Hemispherical Capsule Robot Actuated by Rotating Magnetic Field

Research on Rolling Locomotion Dynamics Characteristics of a Dual Hemispherical Capsule Robot Actuated by Rotating Magnetic Field

Simulation and Verification of a Magnetically Controlled System for a Wireless Capsule Robot

Simulation and Verification of a Magnetically Controlled System for a Wireless Capsule Robot

A Factorial Approach for Optimizing the Design Parameters of a Tissue Attachment Mechanism for Drug Delivery.

Biological macromolecule drugs or biologics are not suited for commonly preferred oral delivery due to their intrinsic instability and physical, chemical, or immunological barriers to the gastrointestinal tract. Ingestible capsule robots (ICR) have become a versatile platform, including use for drug delivery applications for various gastrointestinal pathologies with future potential for systemic drug delivery. In this work, a tissue attachment mechanism (TAM) for a drug delivery ICR is introduced that can facilitate a non-invasive systemic delivery of unaltered biologics via direct injection through the insensate layers of the small intestine. The main prerequisite for achieving systemic drug delivery via this device is to have a strong tissue attachment of the TAM. This study aimed to optimize the attachment success rate for drug delivery and characterize attachment duration in vivo. A fractional factorial approach was used in vivo to identify and optimize factors that most influence attachment of the TAM to maximize attachment rate. Multiple in vivo optimization levels were performed using the small intestine of anesthetized pigs, and an attachment success rate of 92% was achieved. Optimal TAMs were surgically placed in vivo to determine the duration of attachment following anesthetization and surgery recovery. The average in vivo attachment duration was 32.2±9.4 hours. This work establishes a device for consistent and reliable attachment duration, making the TAM a suitable candidate for a 24-hour systemic drug delivery platform.

Hybrid 6-DoF Magnetic Localization for Robotic Capsule Endoscopes Compatible With High-Grade Magnetic Field Navigation

The paper proposes a hybrid 6 degrees of freedom localization system for endoscopic magnetic capsules, compatible with external high-grade permanent magnetic locomotion. The proposed localization system, which is able to provide an accurate estimation of the endoscopic capsule pose, finds application in the robotic endoscopy field to provide efficient closed-loop navigation of a magnetically-driven tethered capsule. It takes advantage of two optimization steps based on a triangulation approach, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.</i> (1) mathematical approximations of the magnetic field, and (2) minimization of the magnetic field mean square deviation. The proposed localization system was tested in two different <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-vitro</i> scenarios for mimicking the clinical cases that a magnetic capsule would encounter during tele-operated magnetic navigation. The development phase was preceded by an in-depth work-space analysis to lay the groundwork for the localization design and implementation. Results of the hybrid 6 degrees of freedom localization system show a significant accuracy in accordance with the state-of-the-art, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.</i> about 5 mm in position and 5° in orientation, but introducing benefits in expanding the work-space by increasing the number of electromagnets onto the operating table, as an independent solution with respect to the external magnetic locomotion source.

Six-Dimensional Localization of a Robotic Capsule Endoscope Using Magnetoquasistatic Field

This study presents a six-dimensional (6D) localization method and theoretical analysis for a robotic capsule endoscope (RCE). Herein, the challenge of implementing 6D localization for an RCE, with the simultaneous localization of 3D position and 3D orientation, is resolved using optimization with an induced magnetostatic field and RCE kinematics. The optimization is achieved using three transmitting coils (Txs) that are placed in a foundation bed to generate the magnetoquasistatic field and three orthogonal receiving coils (Rxs) that are embedded in the RCE, which is aligned with a capsule coordinate system (CCS), to detect the magnetoquasistatic field. For the 3D position estimation, a nonlinear net magnetic field model is linearized, and a polynomial equation optimization is formulated. The local existence and uniqueness of the solution in the region of interest (ROI) are proved based on the model and simulation. For the 3D orientation estimation, a rotation matrix describing the RCE orientation is computed using the measured magnetic field at the three orthogonal Rxs, and the orthogonality of the rotation matrix is enhanced by using the polar coordinate decomposition. Both simulations and experiments verify the suitability of the proposed method. The maximum error for position and orientation are 1.68+/−0.76 mm and 1.74+/−1.06°, respectively, under a 5 Hz sampling rate in an applicable spherical ROI with a diameter of 10 cm.

An Overview of Robotic Capsules for Drug Delivery to the Gastrointestinal Tract.

The introduction of capsule endoscopy two decades ago marked the beginning of the “small bowel revolution”. Since then, the rapid evolution of microtechnology has allowed the development of drug delivery systems (DDS) designed to address some of the needs that are not met by standard drug delivery. To overcome the complex anatomy and physiology of the gastrointestinal (GI) tract, several DDS have been developed, including many prototypes being designed, built and eventually produced with ingenious drug-release mechanisms and anchoring systems allowing targeted therapy. This review highlights the currently available systems for drug delivery in the GI tract and discusses the needs, limitations, and future considerations of these technologies.

A Compensation Method for Magnetic Localization on Capsule Robot in Medical Application

Aiming at the magnetic positioning accuracy of capsule robot and the magnetic coupling between capsule robot and external driving magnetic field, according to the requirements of capsule robot for position and attitude information, a magnetic positioning compensation method of capsule robot based on magnetic driving system is proposed. This method deduces the error formula according to the magnetic dipole model, optimizes the formula, reduces the number of unknowns, optimizes the calculation process and improves the positioning accuracy. At the same time, a compensation is added to solve the magnetic coupling problem between the external driving magnetic field three-axis Helmholtz coil and the capsule robot. Finally, several groups of experiments verify the effectiveness of the algorithm.