Cesare Stefanini

Design and Fabrication of a Motor Legged Capsule for the Active Exploration of the Gastrointestinal Tract

This paper describes a novel solution for the active locomotion of a miniaturized endoscopic capsule in the gastrointestinal (GI) tract. In particular, the authors present the design, development, and testing of a legged locomotion system embedded in a capsule (with a volume of about 4-5 cm3) and actuated by a brushless minimotor. The actuation mechanism and transmission mechanism are described in detail in order to highlight the compactness of the overall design. This device is provided with four superelastic legs, allowing large stroke advancement in the GI tract, and a CMOS frontal camera, for diagnostic purposes. A dedicated electronic board for controlling the opening angle of the legs and adjusting their speed has been developed. In order to investigate the motion ability of the device, a set of experiments has been carried out. Four different types of superelastic legs have been designed and tested with the objective to identify the best leg configuration for capsule locomotion. Experimental results demonstrate that the device can travel in the digestive tract with a typical speed ranging between 10 and 40 mm/min.

Piezoelectric Energy Harvesting Solutions

This paper reviews the state of the art in piezoelectric energy harvesting. It presents the basics of piezoelectricity and discusses materials choice. The work places emphasis on material operating modes and device configurations, from resonant to non-resonant devices and also to rotational solutions. The reviewed literature is compared based on power density and bandwidth. Lastly, the question of power conversion is addressed by reviewing various circuit solutions.

Shape memory alloy clamping devices of a capsule for monitoring tasks in the gastrointestinal tract

This paper describes the development of an active clamping mechanism to be integrated into a swallowable pill for the diagnosis of the gastrointestinal (GI) tract. The clamping system allows us to stop the pill at desired sites of the GI tract for long monitoring purposes. After discussing the major technical constraints, the design of the core component, i.e. the gripper, based on FEA (finite element analysis), is illustrated as well as its fabrication process. Symmetric and asymmetric gripper designs are described. The actuation is provided by shape memory alloys (SMA), and it is driven by a dedicated electrical interface. Then the working prototypes have been tested in vitro: for both kinds of grippers a pull-back force up to 0.6 N has been measured. A preliminary theoretical model for the gripper has been derived and compared to the experimental results.

Integration of a Miniaturised Triaxial Force Sensor in a Minimally Invasive Surgical Tool

This paper reports preliminary results on design and fabrication of a cutting tool with an integrated triaxial force sensor to be applied in fetal surgery procedures. The outer diameter of the proposed device is 7.4 mm, but a scaled down design can be easily achieved. Linearity and hysteresis tests have been performed for both normal and tangential loadings. A linear transformation relating the sensor output to the external applied force is introduced and discussed. The typical working range for the conceived instrument is around 0.3 N, while 20 N and 1 N are, respectively, maximum normal and tangential forces for which the device robustness has been assessed

Locomotion of a legged capsule in the gastrointestinal tract: theoretical study and preliminary technological results

This work illustrates the analysis of locomotion in the gastrointestinal tract obtainable by a legged capsule for diagnostic and therapeutic purposes. A preliminary simulation of the legged locomotion onto slippery and deformable substrates has been performed and -simultaneously- mechanisms for on board actuation of the legs have been developed and tested. Moreover, an engineering translation of medical needs in endoscopy is presented, with some ad hoc solutions for improving diagnostic capabilities.

Modeling and Experiments on a Legged Microrobot Locomoting in a Tubular, Compliant and Slippery Environment

This paper presents the concept and preliminary modeling of a legged microrobot locomoting in a tubular, compliant and slippery environment. The envisaged application field is related to capsular endoscopy, i.e., the development of a mobile swallowable capsule for navigation inside the gastrointestinal tract for diagnosis and therapy. After introducing and discussing the issue of autonomous locomotion of endoscopic devices, with reference to worldwide ongoing research in the field, the legged solution is proposed and peculiarities of this approach are described. The importance of simulation for developing a legged device is discussed and a locomotion model is presented. Experimental results are described for the definition of biomechanical parameters necessary in the model. Thanks to this work first simulations have been obtained, in which the microrobot’s body moves according to arbitrary gait patterns for the legs and to its interaction with tissue. The resulting tool will be used for the design synthesis, for defining the optimal number of legs and the best number of degrees of freedom for each leg. It will be also used for controlling the device, by identifying the gait pattern to be adopted in order to obtain different capsule movements.

Modeling a vertebrate motor system : pattern generation, steering and control of body orientation

The lamprey is one of the few vertebrates in which the neural control system for goal-directed locomotion including steering and control of body orientation is well described at a cellular level. In this report we review the modeling of the central pattern-generating network, which has been carried out based on detailed experimentation. In the same way the modeling of the control system for steering and control of body orientation is reviewed, including neuromechanical simulations and robotic devices.

CoCoRo -- The Self-Aware Underwater Swarm

The EU-funded CoCoRo project studies heterogeneous swarms of AUVs used for the purposes of under water monitoring and search. The CoCoRo underwater swarm system will combine bio-inspired motion principles with biologically-derived collective cognition mechanisms to provide a novel robotic system that is scalable, reliable and flexible with respect its behavioural potential. We will investigate and develop swarm-level emergent self-awareness, taking biological inspiration from fish, honeybees, the immune system and neurons. Low-level, local information processing will give rise to collective-level memory and cognition. CoCoRo will develop a novel bio-inspired operating system whose default behaviour will be to provide AUV shoaling functionality and the maintenance of swarm coherence. Collective discrimination of environmental properties will be processed on an individual-or on a collective-level given the cognitive capabilities of the AUVs. We will investigate collective self-recognition through experiments inspired by ethology and psychology, allowing for the quantification of collective cognition.

A Computer-Assisted Robotic Ultrasound-Guided Biopsy System for Video-Assisted Surgery

Current ultrasound-guided biopsy procedures used in videoassisted surgery suffer from limitations due to difficult triangulation and manual positioning of the biopsy needle. We present a prototype computer-assisted robotic system for needle positioning that operates in a synergistic way with the clinician. The performance of the system in terms of positioning accuracy and execution time is assessed. Results suggest suitability for clinical use.

Lateralisation of aggressive displays in a tephritid fly

Lateralisation (i.e. different functional and/or structural specialisations of the left and right sides of the brain) of aggression has been examined in several vertebrate species, while evidence for invertebrates is scarce. In this study, we investigated lateralisation of aggressive displays (boxing with forelegs and wing strikes) in the Mediterranean fruit fly, Ceratitis capitata. We attempted to answer the following questions: (1) do medflies show lateralisation of aggressive displays at the population-level; (2) are there sex differences in lateralisation of aggressive displays; and (3) does lateralisation of aggression enhance fighting success? Results showed left-biased population-level lateralisation of aggressive displays, with no consistent differences among sexes. In both male-male and female-female conflicts, aggressive behaviours performed with left body parts led to greater fighting success than those performed with right body parts. As we found left-biased preferential use of body parts for both wing strikes and boxing, we predicted that the left foreleg/wing is quicker in exploring/striking than the right one. We characterised wing strike and boxing using high-speed videos, calculating mean velocity of aggressive displays. For both sexes, aggressive displays that led to success were faster than unsuccessful ones. However, left wing/legs were not faster than right ones while performing aggressive acts. Further research is needed on proximate causes allowing enhanced fighting success of lateralised aggressive behaviour. This is the first report supporting the adaptive role of lateralisation of aggressive displays in insects.