We present a medical-needle-sized robotic tube with multi-degrees of freedom (M-DOF) rotational hinge joints at the instrument tip, fabricated by two-axis laser micro-machining. Due to the presence of an ample working channel and direct tip controllability, this tube is a potential candidate for the precise delivery of radioactive seeds, probes and micro-forceps to regions of interest within the human body. In this paper, the advantages of the proposed hinged instrument are studied in contrast with that of flexure joints, which include-fine angle control (posability), and a shorter joint length that enables compact articulation. In addition, the joint strength both in the axial and lateral directions was experimentally investigated to demonstrate its feasibility as a robust delivery platform. Further, the intuitive nature of hinge rotation permits the use of a simple kinematic model for accurate tip motion control, under fewer simplifying assumptions than flexure joints which are impeded by material non-linearity and geometric discontinuities. An instrumented prototype was used to test this model by delivering a laser beam along a prescribed path (synonymous to simple ablation tasks). The observed RMS position error for the projected beam was ~0.364 mm.

We present a transformable catheter head structure for endoscopic catheter allowing the simultaneous use of a camera module and a large tool channel introduced through a small incision. At the site of interest, the head with a camera can be expanded from the initial straight configuration, which opens a window for advancing a tool that is located behind the camera. Two different designs were proposed and prototyped. One option has flexure joints directly fabricated at the distal end of a polymer catheter by laser micro-machining, while another design employs a hinged metal head assembled at the tip of the same type of catheter. The kinematic behavior of each head was evaluated during the head-up and tip steering motions, and compared with each other to draw a selection guideline between them. Experimental results prove the feasibility of the proposed head structure for smarter endoscopic catheters.

In this paper, we present the design of a steerable needle with proximal notch patterns for compliance and an embedded rotational tip joint for articulation. The device is fabricated by laser machining NiTi tube so that an inner working channel exists (to enable delivery of fluids, drugs or microtools) and no assembly is required for the joints. We formulate its model based on the classical Cosserat Rod theory. This is extended with incremental state prediction and a simple spring model for tissue reaction to integrate into a planning algorithm based on Dynamic Region RRT which efficiently explores the needle's state space. The planner was initialized with a target zone and arbitrary anatomical obstacles before running simulations which propagated incremental state changes at every step while adhering to constraints based on the physical system. Finally, we demonstrate the steering capability of the needle through insertion tests into a phantom.

Kinematic models of concentric tube robots have matured from considering only tube bending to considering tube twisting as well as external loading. While these models have been demonstrated to approximate actual behavior, modeling error can be significant for medical applications that often call for positioning accuracy of 1-2mm. As an alternative to moving to more complex models, this paper proposes using sensing to adaptively update model parameters during robot operation. Advantages of this method are that the model is constantly tuning itself to provide high accuracy in the region of the workspace where it is currently operating. It also adapts automatically to changes in robot shape and compliance associated with the insertion and removal of tools through its lumen. As an initial exploration of this approach, a recursive on-line estimator is proposed and evaluated experimentally.

An active needle is proposed for the development of magnetic resonance imaging (MRI)-guided percutaneous procedures. The needle uses a low-transition-temperature shape memory alloy (LT SMA) wire actuator to produce bending in the distal section of the needle. Actuation is achieved with internal optical heating using laser light transported via optical fibers and side coupled to the LT SMA. A prototype, with a size equivalent to a standard 16-gauge biopsy needle, exhibits significant bending, with a tip deflection of more than 14° in air and 5° in hard tissue. A single-ended optical sensor with a gold-coated tip is developed to measure the curvature independently of temperature. The experimental results in tissue phantoms show that human tissue causes fast heat dissipation from the wire actuator; however, the active needle can compensate for typical targeting errors during prostate biopsy.

Fiber Bragg gratings (FBG)-based optical sensors are a promising real-time technique for sensing the 3D curvature of continuum robots. Existing implementations, however, have relied on embedding optical fibers in small-diameter metal wires or needles. This paper proposes polymer tubes as an alternative substrate for the fibers. This approach separates the sensors from the robot structural components while using a minimal amount of the robot's tool lumen and providing the potential of inexpensive fabrication. Since the fibers are stiffer than the polymer substrate, however, design challenges arise in modeling strain transfer between the fibers and the tube substrate. To investigate the potential of this approach, a strain transfer model is derived and validated through simulation and experiment.

A side optical actuation method is presented for a slender MR-compatible active needle. The needle includes an active region with a shape memory alloy (SMA) wire actuator, where the wire generates a contraction force when optically heated by a laser delivered though optical fibers, producing needle tip bending. A prototype, with multiple side heating spots, demonstrates twice as fast an initial response compared to fiber tip heating when 0.8 W of optical power is applied. A single-ended optical sensor with a gold reflector is also presented to measure the curvature as a function of optical transmission loss. Preliminary tests with the sensor prototype demonstrate approximately linear response and a repeatable signal, independent of the bending history.

An active needle is proposed for the development of MRI guided percutaneous procedures. The needle uses internal laser heating, conducted via optical fibers, of a shape memory alloy (SMA) actuator to produce bending in the distal section of the needle. Active bending of the needle as it is inserted allows it to reach small targets while overcoming the effects of interactions with surrounding tissue, which can otherwise deflect the needle away from its ideal path. The active section is designed to bend preferentially in one direction under actuation, and is also made from SMA for its combination of MR and bio-compatibility and its superelastic bending properties. A prototype, with a size equivalent to standard 16G biopsy needle, exhibits significant bending with a tip rotation of more than 10°. A numerical analysis and experiments provide information concerning the required amount of heating and guidance for design of efficient optical heating systems.

Force sensing is an essential requirement for dexterous robot manipulation. We describe composite robot end-effectors that incorporate optical fibers for accurate force sensing and estimation of contact locations. The design is inspired by the sensors in arthropod exoskeletons that allow them to detect contacts and loads on their limbs. In this paper, we present a fabrication process that allows us to create hollow multimaterial structures with embedded fibers and the results of experiments to characterize the sensors and controlling contact forces in a system involving an industrial robot and a two-fingered dexterous hand. We also briefly describe the optical-interrogation method used to measure multiple sensors along a single fiber at kilohertz rates for closed-loop force control.

We describe the dynamic testing and control results obtained with an exoskeletal robot finger with embedded fiber optical sensors. The finger is inspired by the designs of arthropod limbs, with integral strain sensilla concentrated near the joints. The use of fiber Bragg gratings (FBGs) allows for embedded sensors with high strain sensitivity and immunity to electromagnetic interference. The embedded sensors are useful for contact detection and for control of forces during fine manipulation. The application to force control requires precise and high-bandwidth measurement of contact forces. We present a nonlinear force control approach that combines signals from an optical interrogator and conventional joint angle sensors to achieve accurate tracking of desired contact forces.

Recently, the microrobot powered by biological muscle actuators was proposed. The cell based actuator utilizes glucose as a power source and thus can apply to the application of a human body or blood vessels. For the structural design of the cell based micro-robot, the contractile force of the muscle powered by cardiac myocytes should be measured. In addition, the contractile force measurement can be used in the static or dynamic simulations of the micro-robot. In this paper, the contractile force measurement system, which is composed of a micro-manipulator, a force transducer, a signal processor and an inverted microscope is proposed. By using the measuring system, the contractile force for both control and micro-patterned cardiac myocytes are measured. From the experimental results, we estimated that the contractile force of cardiac myocytes is about 20-40 /spl mu/N when it is compared between the control cell and the cell on micro-pattern.