Semiautonomous Robotic Manipulator for Minimally Invasive Aortic Valve Replacement

Aortic valve surgery is the preferred procedure for replacing a damaged valve with an artificial one. The ValveTech robotic platform comprises a flexible articulated manipulator and surgical interface supporting the effective delivery of an artificial valve by teleoperation and endoscopic vision. This article presents our recent work on force-perceptive, safe, semiautonomous navigation of the ValveTech platform prior to valve implantation. First, we present a force observer that transfers forces from the manipulator body and tip to a haptic interface. Second, we demonstrate how hybrid forward/inverse mechanics, together with endoscopic visual servoing, lead to autonomous valve positioning. Benchtop experiments and an artificial phantom quantify the performance of the developed robot controller and navigator. Valves can be autonomously delivered with a 2.0±0.5 mm position error and a minimal misalignment of 3.4±0.9°. The hybrid force/shape observer (FSO) algorithm was able to predict distributed external forces on the articulated manipulator body with an average error of 0.09 N. FSO can also estimate loads on the tip with an average accuracy of 3.3%. The presented system can lead to better patient care, delivery outcome, and surgeon comfort during aortic valve surgery, without requiring sensorization of the robot tip, and therefore obviating miniaturization constraints.</p

Novel Robotic Approach for Minimally Invasive Aortic Heart Valve Surgery

Aortic heart valve replacement is a major surgical intervention, traditionally requiring a large thoracotomy. However, current advances in Minimally Invasive Surgery and Surgical Robotics can offer the possibility to perform the intervention through a narrow mini thoracotomy. The presented surgical robot and proposed surgical scenario aims to provide a highly controllable means for efficiently conducting valve replacement by endoscopic vision. The robot, consisting of a series of joints, is a cable actuated manipulator for reaching the operative site and delivering the valve at the required position. The robot is equipped with endoscopic cameras (to find the hinge points) and three stabilizing flaps (to stabilize the manipulator) for guarantying the proper valve placement. The manipulator is validated by experimental results of flaps' force and camera visions in artificial vessels

Toward dosing precision and insulin stability in an artificial pancreas system

A fully implantable artificial pancreas (AP) still represents the holy grail for diabetes treatment. The quest for efficient miniaturized implantable insulin pumps, able to accurately regulate the blood glucose profile and to keep insulin stability, is still persistent. This work describes the design and testing of a microinjection system connected to a variable volume insulin reservoir devised to favor insulin stability during storage. The design, the constitutive materials, and the related fabrication techniques were selected to favor insulin stability by avoiding-or at least limiting-hormone aggregation. We compared substrates made of nylon 6 and Teflon, provided with different surface roughness values due to the employed fabrication procedures (i.e., standard machining and spray deposition). Insulin stability was tested in a worst case condition for 14 days, and pumping system reliability and repeatability in dosing were tested over an entire reservoir emptying cycle. We found that nylon 6 guarantees a higher insulin stability than Teflon and that independent of the material used, larger roughness determines a higher amount of insulin aggregates. A dedicated rotary pump featured by a 1-lL delivery resolution was developed and connected through a proper gear mechanism to a variable volume air-tight insulin reservoir. The microinjection system was also able to operate in a reverse mode to enable the refilling of the implanted reservoir. The developed system represents a fundamental building block toward the development of a fully implantable AP and could be advantageously integrated even in different implantable drug delivery apparatus (e.g., for pain management)

A Spring-based Inductive Sensor for Soft and Flexible Robots

The development of flexible and soft robots generates new needs in terms of instrumentation, as large encountered deformations require highly stretchable strain sensors. In this regard, we contribute to the adoption of inductive sensors by providing tools to model and exploit them and showing their relevance experimentally. First, strain estimation based on voltage measurement is proposed. Compared to direct inductance evaluation, the principle is easier to implement and opens the possibility to optimize the measurement performances by tuning the circuit components and interrogation frequency. The possibility of performing a single sensor calibration independently via the elongation mode during strain sensing is outlined. A detailed characterization is then performed, which shows that the sensor produces a low hysteresis of 0.1%, a precision in the order of 0.14%, and an accuracy of 0.9%. Finally, two proofs of concept are proposed: 1) the integration with a pneumatic artificial muscle (PAM) that demonstrates the added value of the sensor for a model-free precise control of a soft system and 2) the closed-loop control of a flexible bending manipulator using the inductive sensor. The performance in the closed-loop control is demonstrated, with a sensing element that is easy to integrate mechanically, strengthening its potential to be used as a structural element as well

Soft Graspers for Safe and Effective Tissue Clutching in Minimally Invasive Surgery

Objective: Surgical graspers must be safe, not to damage tissue, and effective, to establish a stable contact for operation. For conventional rigid graspers, these requirements are conflicting and tissue damage is often induced. We thus proposed novel soft graspers, based on morphing jaws that increase contact area with clutching force. Methods: We introduced two soft jaw concepts: DJ and CJ. They were designed (using analytical and numerical models) and prototyped (10 mm diameter, 10 mm span). Corresponding graspers were obtained by integrating the jaws into a conventional tool used in the dVRK surgical robotics platform. Morphing performance was experimentally characterized. Jaw-tissue interaction was quantitatively assessed through damage indicators obtained from ex vivo tests and histological analysis, also comparing DJ, CJ and dVRK rigid jaws. Soft graspers were demonstrated through ex vivo tests on dVRK. Ex vivo tests and related analysis were devised/performed with medical doctors. Results: Design goal was achieved for both soft jaws: by morphing, contact area exceeded by 20 — 30 % the maximum area allowed by encumbrance specifications to rigid jaws. Experimental characterization was in good agreement with model predictions (error ≈ 4%). Damage indicators showed differences amongst DJ, CJ and dVRK jaws (ANOVA p-value = 0.0005): damage was one order of magnitude lower for soft graspers (each pairwise comparison was statistically significant). Conclusion: We proposed and demonstrated soft graspers potentially less harmful to tissue than conventional graspers. Significance: Beyond minimally invasive surgery, the proposed concepts and design methodology can foster the development of graspers for soft robotics

Soft Graspers for Safe and Effective Tissue Clutching in Minimally Invasive Surgery

Surgical graspers must be safe, not to damage tissue, and effective, to establish a stable contact for operation. For conventional rigid graspers, these requirements are conflicting and tissue damage is often induced. We thus proposed novel soft graspers, based on morphing jaws that increase contact area with clutching force