Gioia Lucarini

A discrete-time localization method for capsule endoscopy based on on-board magnetic sensing

Recent achievements in active capsule endoscopy have allowed controlled inspection of the bowel by magnetic guidance. Capsule localization represents an important enabling technology for such kinds of platforms. In this paper, the authors present a localization method, applied as first step in time-discrete capsule position detection, that is useful for establishing a magnetic link at the beginning of an endoscopic procedure or for re-linking the capsule in the case of loss due to locomotion. The novelty of this approach consists in using magnetic sensors on board the capsule whose output is combined with pre-calculated magnetic field analytical model solutions. A magnetic field triangulation algorithm is used for obtaining the position of the capsule inside the gastrointestinal tract. Experimental validation has demonstrated that the proposed procedure is stable, accurate and has a wide localization range in a volume of about 18 × 103 cm3. Position errors of 14 mm along the X direction, 11 mm along the Y direction and 19 mm along the Z direction were obtained in less than 27 s of elaboration time. The proposed approach, being compatible with magnetic fields used for locomotion, can be easily extended to other platforms for active capsule endoscopy.

Experimental assessment of a novel robotically-driven endoscopic capsule compared to traditional colonoscopy

BACKGROUND Despite colonoscopy represents the conventional diagnostic tool for colorectal pathology, its undeniable discomfort reduces compliance to screening programmes. AIMS To evaluate feasibility and accuracy of a novel robotically-driven magnetic capsule for colonoscopy as compared to the traditional technique. METHODS Eleven experts and eleven trainees performed complete colonoscopy by robotic magnetic capsule and by conventional colonoscope in a phantom ex vivo model (artificially clean swine bowel). Feasibility, overall accuracy to detect installed pins, procedure elapsed time and intuitiveness were measured for both techniques in both operator groups. RESULTS Complete colonoscopy was feasible in all cases with both techniques. Overall 544/672 pins (80.9%) were detected by experimental capsule procedure, while 591/689 pins (85.8%) were detected within conventional colonoscopy procedure (P=ns), thus establishing non-inferiority. With the experimental capsule procedure, experts detected 74.2% of pins vs. 87.6% detected by trainees (P<0.0001). Overall time to complete colon inspection by robotic capsule was significantly higher than by conventional colonoscopy (556±188s vs. 194±158s, respectively; P=0.0001). CONCLUSION With the limitations represented by an ex vivo setting (artificially clean swine bowel and the absence of peristalsis), colonoscopy by this novel robotically-driven capsule resulted feasible and showed adequate accuracy compared to conventional colonoscopy.

A Comparative Evaluation of Control Interfaces for a Robotic-Aided Endoscopic Capsule Platform

Wireless capsule endoscopy offers significant advantages compared with traditional endoscopic procedures, since it limits the invasiveness of gastrointestinal tract screening and diagnosis. Moreover, active locomotion devices would allow endoscopy to be performed in a totally controlled manner, avoiding failures in the correct visualization of pathologies. Previous works demonstrated that magnetic locomotion through a robotic-aided platform would allow us to reach this goal reliably. In this paper, the authors present a comparative evaluation of control methodologies and user interfaces for a robotic-aided magnetic platform for capsule endoscopy, controlled through human-robot cooperative and teleoperated control algorithms. A detailed statistical analysis of significant control parameters was performed: teleoperated control is the more reliable control approach, and a serial kinematic haptic device results as the most suitable control interface to perform effective robotic-aided endoscopic procedures.

A New Concept for Magnetic Capsule Colonoscopy Based on an Electromagnetic System

Traditional endoscopy based on flexible endoscopes is reliable and effective, but poorly tolerated by patients; it also requires extended training by physicians. In order to reduce the invasiveness of these procedures, wireless passive capsule endoscopy has been proposed and clinically used during the past decade. A capsule endoscope with an active locomotion mechanism is desirable for carrying out controllable interactive procedures that are normally not possible using passive devices. Due to many difficulties in embedding actuators in swallowable devices, many researchers and companies have adopted an external magnetic field actuation solution. Magnetic resonance modified systems or permanent magnets are used to manoeuvre capsules remotely; however, both these cases present some limitations: magnetic resonance systems are bulky and expensive and permanent magnets are intrinsically unstable to control, and it is impossible to switch them off. Within this framework, the authors present the design and assessment of a magnetic system for endoscopic capsules based on an electromagnetic approach. In particular, the use of a single electromagnet was proposed and investigated: magnetic attraction, locomotion forces and magnetic torques were modelled for guaranteeing the reliable navigation of the capsule and based on these specifications, an electromagnet was designed, developed and experimentally evaluated. The results demonstrated the feasibility of the proposed approach for active locomotion capsule endoscopy.

Untethered magnetic millirobot for targeted drug delivery.

This paper reports the design and development of a novel millimeter-sized robotic system for targeted therapy. The proposed medical robot is conceived to perform therapy in relatively small diameter body canals (spine, urinary system, ovary, etc.), and to release several kinds of therapeutics, depending on the pathology to be treated. The robot is a nearly-buoyant bi-component system consisting of a carrier, in which the therapeutic agent is embedded, and a piston. The piston, by exploiting magnetic effects, docks with the carrier and compresses a drug-loaded hydrogel, thus activating the release mechanism. External magnetic fields are exploited to propel the robot towards the target region, while intermagnetic forces are exploited to trigger drug release. After designing and fabricating the robot, the system has been tested in vitro with an anticancer drug (doxorubicin) embedded in the carrier. The efficiency of the drug release mechanism has been demonstrated by both quantifying the amount of drug released and by assessing the efficacy of this therapeutic procedure on human bladder cancer cells.

Wireless swimming microrobots: Design and development of a 2 DoF magnetic-based system

In this work, the design and development of an integrated platform for the steering of swimming microrobot is reported. The system consists of: a near-spherical soft and buoyant magnetic microrobot (with a diameter of about 500 μm) conceived for operation in liquid; a wireless magnetic steering system, including a compact magnetic field generator based on two pairs of Helmholtz and Maxwell coils; an electronic system for their driving; a control software; a joypad physical user interface; and, the micro-arena as working environment. The platform design fulfills the requirements for the “Mobility Task” of the 2011 NIST Mobile Microrobotics Challenge. The results obtained from preliminary validation experiments confirm that the microrobots can move in a fully controlled way, successfully accomplishing an intricate eight-shape path, as required, in the water filled micro-arena. In particular we achieved a maximum average speed of 0.71 mm/s and an exceptionally smooth motion.

Electromagnetic Control System for Capsule Navigation: Novel Concept for Magnetic Capsule Maneuvering and Preliminary Study.

The gastrointestinal tract is home of some of the most deadly human diseases. The main problems are related to the difficulty of accessing it for diagnosis or intervention and concomitant patient discomfort. The flexible endoscopy technique has established itself in medical practice due to its high diagnostic accuracy and reliability; however, several technical limitations still remain and the procedure is poorly tolerated by patients. The use of magnetic fields to control and steer endoscopic capsules is increasing in minimally invasive procedures. In fact, magnetic coupling is one of the few physical phenomena capable of transmitting motion beyond a physical barrier, allowing for the compact design of the device itself. In this framework, the authors present the preliminary design and assessment of a magnetic coupling for magnetic endoscopic capsules considering an electromagnetic approach. In particular, a novel toroidal electromagnet is proposed as the control and driving system. The system concept, design, and preliminary results are reported.

Navigation of Magnetic Microrobots With Different User Interaction Levels

Micro-technologies based on wirelessly powered and manoeuvred submillimeter device, i.e.,microrobots, are attracting growing attention. Their application in lab-on-a-chip systems, such as micromanipulation and in vitro cell sorting, is expected to steeply increase. However, the actuation, powering and control of microrobots are challenges that still need concrete solutions. Magnetic fields generally enable wireless navigation of microrobots, but proper control architectures and magnetic navigation systems are needed, depending on the specific task and on the level of interaction required to the user. Here we present a magnetic navigation platform intended for lab-on-a-chip applications and we address its usability with different levels of human involvement by using two control architectures: teleoperated and autonomous. We perform an experimental analysis to demonstrate that both architectures, enrolling different levels of interaction by the user, lead to reliable execution of the microrobotic task. First, we validate the open-loop response of the microrobotic system, and second, we evaluate the performance of the system by testing both control architectures with a standard mobility task. The results show that users can teleoperate the microrobot with 100% success rate, in 14.4±1.9s with a normalized spatial mean error of 0.60±0.13. Moreover, results show a fast decaying learning curve for the users involved in the study. Compared to this, when the navigation task is performed by the autonomous control, 100% success rate, a time of 8.0±0.5s and a normalized spatial mean error of 0.50±0.05 are obtained. Finally, we quantitatively demonstrate how both control methodologies enable very smooth movements of the microrobot, suggesting application for any task where repeatable and dexterous movements in liquid microenvironments are key requirements.

A Power-efficient Propulsion Method for Magnetic Microrobots

Current magnetic systems for microrobotic navigation consist of assemblies of electromagnets, which allow for the wireless accurate steering and propulsion of sub-millimetric bodies. However, large numbers of windings and/or high currents are needed in order to generate suitable magnetic fields and gradients. This means that magnetic navigation systems are typically cumbersome and require a lot of power, thus limiting their application fields. In this paper, we propose a novel propulsion method that is able to dramatically reduce the power demand of such systems. This propulsion method was conceived for navigation systems that achieve propulsion by pulling microrobots with magnetic gradients. We compare this power-efficient propulsion method with the traditional pulling propulsion, in the case of a microrobot swimming in a micro-structured confined liquid environment. Results show that both methods are equivalent in terms of accuracy and the velocity of the motion of the microrobots, while the new approach requires only one ninth of the power needed to generate the magnetic gradients. Substantial equivalence is demonstrated also in terms of the manoeuvrability of user-controlled microrobots along a complex path.

Magnetic Field-Based Technologies for Lab-on-a-Chip Applications

In the last decades, LOC technologies have represented a real breakthrough in the field of in vitro biochemical and biological analyses. However, the integration of really complex functions in a limited space results extremely challenging and proper working princi‐ ples should be identified. In this sense, magnetic fields revealed to be extremely promising. Thanks to the exploitation of external magnetic sources and to the integration of magnetic materials, mainly high aspect ratio micro-/nanoparticles, non-contact manipulation of biological and chemical samples can be enabled. In this chapter, magnetic field-based technologies, their basic theory, and main applications in LOC scenario will be descri‐ bed by foreseeing also a deeper interaction/integration with the typical technologies of microrobotics. Attention will be focused on magnetic separation and manipulation, by taking examples coming from traditional LOC devices and from microrobotics.