A Monolithic Compliant Continuum Manipulator: a Proof-of-Concept Study

Continuum robots have the potential to form an effective interface between the patient and surgeon in minimally invasive procedures. Magnetic actuation has the potential for accurate catheter steering, reducing tissue trauma and decreasing radiation exposure. In this paper, a new design of a monolithic metallic compliant continuum manipulator is presented, with flexures for precise motion. Contactless actuation is achieved using time-varying magnetic fields generated by an array of electromagnetic coils. The motion of the manipulator under magnetic actuation for planar deflection is studied. The mean errors of the theoretical model compared to experiments over three designs are found to be 1.9 mm and 5.1degrees in estimating the in-plane position and orientation of the tip of the manipulator, respectively and 1.2 mm for the whole shape of the manipulator. Maneuverability of the manipulator is demonstrated by steering it along a path of known curvature and also through a gelatin phantom which is visualized in real time using ultrasound imaging, substantiating its application as a steerable surgical manipulator

Temperature Assessment During Radio Frequency Ablation in Ex Vivo Long Bone by Fiber Bragg Grating Sensors

Thermal ablation treatments (TATs) are promising alternatives to traditional surgery for bone cancer eradication. Among several TATs, radio frequency ablation (RFA) has gained considerable ground in treating bone cancer. Therefore, tracking temperature is paramount in ensuring complete tumor destruction without injuring adjacent structures. Despite the widespread use of RFA for bone tumors, investigations on temperature distribution during this procedure are so far lacking. To date, only thermocouples and thermistors have been proposed to measure temperature during RFA in bone. However, these sensors are intended to measure temperature at a single point without information about heat propagation into the tissue during ablation. Within this context, fiber Bragg grating sensors (FBGs) can play a crucial role since their multiplexing capability enables temperature measurement at several locations. This work seeks to fill this gap by providing new insights into RFA effects on bone tissue. Experiments are performed on ex vivo porcine femurs. During trials, two commercial stainless-steel needles equipped with an optical fiber housing six FBGs each were employed to record temperature over time. This solution allowed for monitoring temperature in 12 tissue points inside the bone at a fixed distance from the RF probe, thus gaining information about the thermal distribution in a large tissue area over time. This study paves the way for a more in-depth understanding of the efficacy of RFA in bone tissue, thus providing a powerful method for temperature monitoring, potentially enhancing the treatment outcomes.</p

Minimally designed thermo-magnetic dual responsive soft robots for complex applications

The fabrication of thermo-magnetic dual-responsive soft robots often requires intricate designs to implement complex locomotion patterns and utilize the implemented responsive behaviors. This work demonstrates a minimally designed soft robot based on poly-N-isopropylacrylamide (pNIPAM) and ferromagnetic particles, showcasing excellent control over both thermo- and magnetic responses. Free radical polymerization enables the magnetic particles to be entrapped homogeneously within the polymeric network. The integration of magnetic shape programming and temperature response allows the robot to perform various tasks including shaping, locomotion, pick-and-place, and release maneuvers of objects using independent triggers. The robot can be immobilized in a gripping state through magnetic actuation, and a subsequent increase in temperature transitions the robot from a swollen to a collapsed state. The temperature switch enables the robot to maintain a secured configuration while executing other movements via magnetic actuation. This approach offers a straightforward yet effective solution for achieving full control over both stimuli in dual-responsive soft robotics

A Snake-Inspired Multi-Segmented Magnetic Soft Robot towards Medical Applications

Magnetically-actuated soft robots have potential for medical application but require further innovation on functionality and biocompatibility. In this letter, a multi-segmented snake-inspired soft robot with dissolvable and biocompatible segments is designed. The actuation response under external magnetic field is investigated through simulations and experiments. A dissolve-controllable mixture of gelatin, glycerol and water (GGW) in a mass ratio of 1:5:6 is used to form the structure of the robot. The dissolution of GGW in water and mucus is tested. Magnetic cubes made of silicone rubber mixed with ferromagnetic particles are used to achieve snake-like motion under the influence of a rotating magnetic field. The motion of the robot is tested under different magnitudes and frequencies of the magnetic field. The ability of the robot to navigate obstacles, move over ground and under water as well as on the oil-coated surface, dissolve and release a drug is demonstrated through experiments. The combination of multi-segmented design and biocompatible and dissolvable materials illustrates the potential of such robots for medical applications

Bio-Inspired Terrestrial Motion of Magnetic Soft Millirobots

Magnetic soft robots have the combined advantages of contactless actuation, requiring no on-board power source, and having flexible bodies that can adapt to unstructured environments. In this study, four milli-scale soft robots are designed (Inchworm, Turtle, Quadruped, and Millipede) and their actuation under external magnetic fields is investigated with the objective of reproducing multi-limbed motion patterns observed in nature. Magnetic properties are incorporated into a silicone polymer by mixing in ferromagnetic microparticles before curing. The magnet-polymer composite is used to fabricate soft magnetic parts, with pre-determined magnetization profiles achieved using a 1 T field. The resulting soft robots are actuated under external magnetic fields of 10–35 mT which are controlled using an array of six electromagnetic coils. The achieved motion patterns are analyzed over five iterations and the motions are quantified in terms of body lengths traversed per actuation cycle and speed of displacement. The speed of the specimens is calculated to be in the range of 0.15–0.37 mm/s for the actuation field used here. The ability of the soft robots to traverse uneven terrain is also tested, with the Turtle and the Millipede demonstrating successful motion