Total mesorectal excision using a soft and flexible robotic arm: a feasibility study in cadaver models.

BACKGROUND: Sponsored by the European Commission, the FP7 STIFF-FLOP project aimed at developing a STIFFness controllable Flexible and Learn-able manipulator for surgical operations, in order to overcome the current limitations of rigid-link robotic technology. Herein, we describe the first cadaveric series of total mesorectal excision (TME) using a soft and flexible robotic arm for optic vision in a cadaver model. METHODS: TME assisted by the STIFF-FLOP robotic optics was successfully performed in two embalmed male human cadavers. The soft and flexible optic prototype consisted of two modules, each measuring 60 mm in length and 14.3 mm in maximum outer diameter. The robot was attached to a rigid shaft connected to an anthropomorphic manipulator robot arm with six degrees of freedom. The controller device was equipped with two joysticks. The cadavers (BMI 25 and 28 kg/m2) were prepared according to the Thiel embalming method. The procedure was performed using three standard laparoscopic instruments for traction and dissection, with the aid of a 30° rigid optics in the rear for documentation. RESULTS: Following mobilization of the left colonic flexure and division of the inferior mesenteric vessels, TME was completed down to the pelvic floor. The STIFF-FLOP robotic optic arm seemed to acquire superior angles of vision of the surgical field in the pelvis, resulting in an intact mesorectum in both cases. Completion times of the procedures were 165 and 145 min, respectively. No intraoperative complications occurred. No technical failures were registered. CONCLUSIONS: The STIFF-FLOP soft and flexible robotic optic arm proved effective in assisting a laparoscopic TME in human cadavers, with a superior field of vision compared to the standard laparoscopic vision, especially low in the pelvis. The introduction of soft and flexible robotic devices may aid in overcoming the technical challenges of difficult laparoscopic procedures based on standard rigid instruments.

Multi-Axis Force/Torque Sensor Based on Simply-Supported Beam and Optoelectronics.

This paper presents a multi-axis force/torque sensor based on simply-supported beam and optoelectronic technology. The sensor's main advantages are: (1) Low power consumption; (2) low-level noise in comparison with conventional methods of force sensing (e.g., using strain gauges); (3) the ability to be embedded into different mechanical structures; (4) miniaturisation; (5) simple manufacture and customisation to fit a wide-range of robot systems; and (6) low-cost fabrication and assembly of sensor structure. For these reasons, the proposed multi-axis force/torque sensor can be used in a wide range of application areas including medical robotics, manufacturing, and areas involving human-robot interaction. This paper shows the application of our concept of a force/torque sensor to flexible continuum manipulators: A cylindrical MIS (Minimally Invasive Surgery) robot, and includes its design, fabrication, and evaluation tests.

Towards Standardized Acquisition with a Dual-probe Ultrasound Robot for Fetal Imaging.

Standardized acquisitions and diagnoses using robots and AI would potentially increase the general usability and reliability of medical ultrasound. Working towards this prospect, this paper presents the recent developments of a standardized acquisition workflow using a novel dual-probe ultrasound robot, for a project known as intelligent Fetal Imaging and Diagnosis (iFIND). The workflow includes an abdominal surface mapping step to obtain a non-parametric spline surface, a rule-based end-point calculation method to position each individual joint, and a motor synchronization method to achieve a smooth motion towards a target point. The design and implementation of the robot are first presented in this paper and the proposed workflow is then explained in detail with simulation and volunteer experiments performed and analyzed. The closed-form analytical solution to the specific motion planning problem has demonstrated a reliable performance controlling the robot to move towards the expected scanning areas and the calculated proximity of the robot to the surface shows that the robot maintains a safe distance while moving around the abdomen. The volunteer study has successfully demonstrated the reliable working and controllability of the robot in terms of acquiring desired ultrasound views. Our future work will focus on improving the motion planning, and on integrating the proposed standardized acquisition workflow with newly- developed ultrasound image processing methods to obtain diagnostic results in an accurate and consistent way.

An eye tracking based virtual reality system for use inside magnetic resonance imaging systems.

Patients undergoing Magnetic Resonance Imaging (MRI) often experience anxiety and sometimes distress prior to and during scanning. Here a full MRI compatible virtual reality (VR) system is described and tested with the aim of creating a radically different experience. Potential benefits could accrue from the strong sense of immersion that can be created with VR, which could create sense experiences designed to avoid the perception of being enclosed and could also provide new modes of diversion and interaction that could make even lengthy MRI examinations much less challenging. Most current VR systems rely on head mounted displays combined with head motion tracking to achieve and maintain a visceral sense of a tangible virtual world, but this technology and approach encourages physical motion, which would be unacceptable and could be physically incompatible for MRI. The proposed VR system uses gaze tracking to control and interact with a virtual world. MRI compatible cameras are used to allow real time eye tracking and robust gaze tracking is achieved through an adaptive calibration strategy in which each successive VR interaction initiated by the subject updates the gaze estimation model. A dedicated VR framework has been developed including a rich virtual world and gaze-controlled game content. To aid in achieving immersive experiences physical sensations, including noise, vibration and proprioception associated with patient table movements, have been made congruent with the presented virtual scene. A live video link allows subject-carer interaction, projecting a supportive presence into the virtual world.

Development and Testing of an Ultrasound-Compatible Cardiac Phantom for Interventional Procedure Simulation Using Direct Three-Dimensional Printing.

Organ phantoms are widely used for evaluating medical technologies, training clinical practitioners, as well as surgical planning. In the context of cardiovascular disease, a patient-specific cardiac phantom can play an important role for interventional cardiology procedures. However, phantoms with complicated structures are difficult to fabricate by conventional manufacturing methods. The emergence of three-dimensional (3D) printing with soft materials provides the opportunity to produce phantoms with complex geometries and realistic properties. In this work, the aim was to explore the use of a direct 3D printing technique to produce multimodal imaging cardiac phantoms and to test the physical properties of the new materials used, namely the Poro-Lay series and TangoPlus. The cardiac phantoms were first modeled using real data segmented from a patient chest computer tomography (CT) scan and then printed with the novel materials. They were then tested quantitatively in terms of stiffness and ultrasound (US) acoustic values and qualitatively with US, CT, and magnetic resonance imaging systems. From the stiffness measurements, Lay-fomm 40 had the closest Young's modulus to real myocardium with an error of 29-54%, while TangoPlus had the largest difference. From the US acoustics measurements, Lay-fomm 40 also demonstrated the closest soft tissue-mimicking properties with both the smallest attenuation and impedance differences. Furthermore, the imaging results show that the phantoms are compatible with multiple imaging modalities and thus have potential to be used for interventional procedure simulation and testing of novel interventional devices. In conclusion, direct 3D printing with Poro-Lay and TangoPlus is a promising method for manufacture of multimodal imaging phantoms with complicated structures, especially for soft patient-specific phantoms.

Optoelectronic Sensor-based Shape Sensing Approach for Flexible Manipulators.

This paper presents a novel two-axis shape sensor based on optical optoelectronic sensors and integrated with a flexible manipulator arm to measure the overall shape of the robotic arm. The disc-shape bio-compatible sensor presented here can be embedded as a sensing system into flexible manipulators and is applicable to the geometry of its structure and to the structure of any other similar multi-segment robotic manipulator. Design and calibration procedures of the device are introduced: experimental results allow defining a sensor matrix for real-time estimation of the pitch and roll of the plate above the sensor and confirms the usefulness of the proposed optical sensing approach.

Mechanically Powered Motion Imaging Phantoms: Proof of Concept.

Motion imaging phantoms are expensive, bulky and difficult to transport and set-up. The purpose of this paper is to demonstrate a simple approach to the design of multi-modality motion imaging phantoms that use mechanically stored energy to produce motion.We propose two phantom designs that use mainsprings and elastic bands to store energy. A rectangular piece was attached to an axle at the end of the transmission chain of each phantom, and underwent a rotary motion upon release of the mechanical motor. The phantoms were imaged with MRI and US, and the image sequences were embedded in a 1D non linear manifold (Laplacian Eigenmap) and the spectrogram of the embedding was used to derive the angular velocity over time. The derived velocities were consistent and reproducible within a small error. The proposed motion phantom concept showed great potential for the construction of simple and affordable motion phantoms.

Analysis of a Customized Clutch Joint Designed for the Safety Management of an Ultrasound Robot.

Robotic systems have great potential to assist ultrasound (US) examination. Currently, the safety management method to limit the force that a US robot can apply mostly relies on force sensing and software-based algorithms. This causes the concern that the potential failure of sensors, electrical systems, or software could lead to patient injuries. In this paper, we investigated a customized spring-loaded ball clutch joint designed for a newly developed US robot to passively limit the force applied. The working mechanism of the clutch was modelled and the kinematic-based analysis was performed to understand the variation of the limited force at different postures of the robot. The triggering torque of the clutch was found to be 3928 N·mm, which results in the mean limited force 22.10 ± 1.76 N at the US probe end based on potential postures. The real measurement of the implemented design indicated that the limited force could be set between 17 and 24 N at the neutral posture depending on the preload. With the maximum preload, the mean limited force was found to be 21.98 ± 0.96 N based on 30 repeated measurements. The practically measured results meet the expectation from the theoretical calculation, and the resulting small variation has indicated a good repeatability of the clutch. Based on this evidence, it is concluded that the proposed clutch meets the design aim that it can limit the force applied within a safe range while at the same time ensuring that the required force is applied at different postures.

Elasticity Versus Hyperelasticity Considerations in Quasistatic Modeling of a Soft Finger-Like Robotic Appendage for Real-Time Position and Force Estimation.

Various methods based on hyperelastic assumptions have been developed to address the mathematical complexities of modeling motion and deformation of continuum manipulators. In this study, we propose a quasistatic approach for 3D modeling and real-time simulation of a pneumatically actuated soft continuum robotic appendage to estimate the contact force and overall pose. Our model can incorporate external load at any arbitrary point on the body and deliver positional and force propagation information along the entire backbone. In line with the proposed model, the effectiveness of elasticity versus hyperelasticity assumptions (neo-Hookean and Gent) is investigated and compared. Experiments are carried out with and without external load, and simulations are validated across a range of Young's moduli. Results show best conformity with Hooke's model for limited strains with about 6% average normalized error of position; and a mean absolute error of less than 0.08 N for force applied at the tip and on the body, demonstrating high accuracy in estimating the position and the contact force.

Design and Implementation of a Bespoke Robotic Manipulator for Extra-corporeal Ultrasound.

With the potential for high precision, dexterity, and repeatability, a self-tracked robotic system can be employed to assist the acquisition of real-time ultrasound. However, limited numbers of robots designed for extra-corporeal ultrasound have been successfully translated into clinical use. In this study, we aim to build a bespoke robotic manipulator for extra-corporeal ultrasound examination, which is lightweight and has a small footprint. The robot is formed by five specially shaped links and custom-made joint mechanisms for probe manipulation, to cover the necessary range of motion with redundant degrees of freedom to ensure the patient's safety. The mechanical safety is emphasized with a clutch mechanism, to limit the force applied to patients. As a result of the design, the total weight of the manipulator is less than 2 kg and the length of the manipulator is about 25 cm. The design has been implemented, and simulation, phantom, and volunteer studies have been performed, to validate the range of motion, the ability to make fine adjustments, mechanical reliability, and the safe operation of the clutch. This paper details the design and implementation of the bespoke robotic ultrasound manipulator, with the design and assembly methods illustrated. Testing results to demonstrate the design features and clinical experience of using the system are presented. It is concluded that the current proposed robotic manipulator meets the requirements as a bespoke system for extra-corporeal ultrasound examination and has great potential to be translated into clinical use.

Ultrafast fluxional exchange dynamics in electrolyte solvation sheath of lithium ion battery.

Lithium cation is the charge carrier in lithium-ion battery. Electrolyte solution in lithium-ion battery is usually based on mixed solvents consisting of polar carbonates with different aliphatic chains. Despite various experimental evidences indicating that lithium ion forms a rigid and stable solvation sheath through electrostatic interactions with polar carbonates, both the lithium solvation structure and more importantly fluctuation dynamics and functional role of carbonate solvent molecules have not been fully elucidated yet with femtosecond vibrational spectroscopic methods. Here we investigate the ultrafast carbonate solvent exchange dynamics around lithium ions in electrolyte solutions with coherent two-dimensional infrared spectroscopy and find that the time constants of the formation and dissociation of lithium-ion···carbonate complex in solvation sheaths are on a picosecond timescale. We anticipate that such ultrafast microscopic fluxional processes in lithium-solvent complexes could provide an important clue to understanding macroscopic mobility of lithium cation in lithium-ion battery on a molecular level.

Anchoring like octopus: biologically inspired soft artificial sucker.

This paper presents a robotic anchoring module, a sensorized mechanism for attachment to the environment that can be integrated into robots to enable or enhance various functions such as robot mobility, remaining on location or its ability to manipulate objects. The body of the anchoring module consists of two portions with a mechanical stiffness transition from hard to soft. The hard portion is capable of containing vacuum pressure used for actuation while the soft portion is highly conformable to create a seal to contact surfaces. The module is integrated with a single sensory unit which exploits a fibre-optic sensing principle to seamlessly measure proximity and tactile information for use in robot motion planning as well as measuring the state of firmness of its anchor. In an experiment, a variable set of physical loads representing the weights of potential robot bodies were attached to the module and its ability to maintain the anchor was quantified under constant and variable vacuum pressure signals. The experiment shows the effectiveness of the module in quantifying the state of firmness of the anchor and discriminating between different amounts of physical loads attached to it. The proposed anchoring module can enable many industrial and medical applications where attachment to environment is of crucial importance for robot control.

Highly Sensitive Flexible NH3 Sensors Based on Printed Organic Transistors with Fluorinated Conjugated Polymers.

Understanding the sensing mechanism in organic chemical sensors is essential for improving the sensing performance such as detection limit, sensitivity, and other response/recovery time, selectivity, and reversibility for real applications. Here, we report a highly sensitive printed ammonia (NH3) gas sensor based on organic thin film transistors (OTFTs) with fluorinated difluorobenzothiadiazole-dithienosilole polymer (PDFDT). These sensors detected NH3 down to 1 ppm with high sensitivity (up to 56%) using bar-coated ultrathin (<4 nm) PDFDT layers without using any receptor additives. The sensing mechanism was confirmed by cyclic voltammetry, hydrogen/fluorine nuclear magnetic resonance, and UV/visible absorption spectroscopy. PDFDT-NH3 interactions comprise hydrogen bonds and electrostatic interactions between the PDFDT polymer backbone and NH3 gas molecules, thus lowering the highest occupied molecular orbital levels, leading to hole trapping in the OTFT sensors. Additionally, density functional theory calculations show that gaseous NH3 molecules are captured via cooperation of fluorine atoms and dithienosilole units in PDFDT. We verified that incorporation of functional groups that interact with a specific gas molecule in a conjugated polymer is a promising strategy for producing high-performance printed OTFT gas sensors.

Embedded electro-conductive yarn for shape sensing of soft robotic manipulators.

Flexible soft and stiffness-controllable surgical manipulators enhance the manoeuvrability of surgical tools during Minimally Invasive Surgery (MIS), as opposed to conventional rigid laparoscopic instruments. These flexible and soft robotic systems allow bending around organs, navigating through complex anatomical pathways inside the human body and interacting inherently safe with its soft environment. Shape sensing in such systems is a challenge and one essential requirement for precise position feedback control of soft robots. This paper builds on our previous work integrating multiple optical fibres into a soft manipulator to estimate the robot's pose using light intensity modulation. Here, we present an enhanced version of our embedded bending/shape sensor based on electro-conductive yarn. The new system is miniaturised and able to measure bending behaviour as well as elongation. The integrated yarn material is helically wrapped around an elastic strap and protected inside a 1.5mm outer-diameter stretchable pipe. Three of these resulting stretch sensors are integrated in the periphery of a pneumatically actuated soft manipulator for direct measurement of the actuation chamber lengths. The capability of the sensing system in measuring the bending curvature and elongation of the arm is evaluated.

A continuum body force sensor designed for flexible surgical robotics devices.

This paper presents a novel three-axis force sensor based on optical photo interrupters and integrated with the robot arm STIFF-FLOP (STIFFness controllable Flexible and Learnable Manipulator for Surgical Operations) to measure external interacting forces and torques. The ring-shape bio-compatible sensor presented here embeds the distributed actuation and sensing system of the STIFF-FLOP manipulator and is applicable to the geometry of its structure as well to the structure of any other similar soft robotic manipulator. Design and calibration procedures of the device are introduced: experimental results allow defining a stiffness sensor matrix for real-time estimation of force and torque components and confirm the usefulness of the proposed optical sensing approach.