Compliant Tip Research Articles

Kinematic Modeling and Jacobian-based Control of the COAST Guidewire Robot.

Manual guidewire navigation and placement for minimally invasive surgeries suffer from technical challenges due to imprecise tip motion control to traverse highly tortuous vasculature. Robotically steerable guidewires can address these challenges by actuating a compliant tip through multiple degrees-of-freedom for maneuvering through vascular pathways. In this paper, we detail the kinematic mapping of a COaxially Aligned STeerable (COAST) guidewire robot that is capable of executing follow-the-leader motion in three dimensional vascular pathways. We also develop an analytical Jacobian model to perform velocity kinematics for the robot and finally, we implement Jacobian-based control to demonstrate follow-the-leader motion of the guidewire in free space, within 3D-printed phantoms, and within ex vivo animal vasculature.

Blocks World of Touch: Exploiting the Advantages of All-Around Finger Sensing in Robot Grasping.

Tactile sensing is an essential capability for a robot to perform manipulation tasks in cluttered environments. While larger areas can be assessed instantly with cameras, Lidars, and other remote sensors, tactile sensors can reduce their measurement uncertainties and gain information of the physical interactions between the objects and the robot end-effector that is not accessible via remote sensors. In this paper, we introduce the novel tactile sensor GelTip that has the shape of a finger and can sense contacts on any location of its surface. This contrasts to other camera-based tactile sensors that either only have a flat sensing surface, or a compliant tip of a limited sensing area, and our proposed GelTip sensor is able to detect contacts from all the directions, like a human finger. The sensor uses a camera located at its base to track the deformations of the opaque elastomer that covers its hollow, rigid, and transparent body. Because of this design, a gripper equipped with GelTip sensors is capable of simultaneously monitoring contacts happening inside and outside its grasp closure. Our extensive experiments show that the GelTip sensor can effectively localize these contacts at different locations of the finger body, with a small localization error of approximately 5 mm on average, and under 1 mm in the best cases. Furthermore, our experiments in a Blocks World environment demonstrate the advantages, and possibly a necessity, of leveraging all-around touch sensing in manipulation tasks. In particular, the experiments show that the contacts at different moments of the reach-to-grasp movements can be sensed using our novel GelTip sensor.

Design, prototype development and pre-clinical validation of a novel instrument with a compliant steerable tip to facilitate endoscopic ear surgery

This work presents the design of a novel compliant steerable tip (CST) instrument to facilitate transcanal (or totally) endoscopic ear surgery (TEES). The evolution of the instrument’s design is shown, where prototypes were evaluated by surgeons and their feedback was used to inform the design changes for the next prototype iteration. The final prototype enables the surgeon to articulate the compliant tip to achieve the desired bending curvature while automatically locking in place and providing dissection and suction capabilities. Pre-clinical validation testing was performed in goat and human cadaver models by two surgeons who successfully removed an allograft from the middle ear. Time and the number of blockages while suctioning saline in both cadaver models were measured and compared with current instruments used during TEES. The CST took significantly less time to suction saline within a flooded middle ear compared to the Panetti suction dissector (PSD) for atticus and underwent less blockages than the PSD for atticus, ear drum and sinus tympani instruments, Wilcoxon Method p < .05. Our study demonstrates the development and successful clinical evaluation of a minimally invasive surgical instrument designed to facilitate endoscopic approaches to the ear.

A multiport MR-compatible neuroendoscope: spanning the gap between rigid and flexible scopes.

OBJECTIVE Rigid endoscopes enable minimally invasive access to the ventricular system; however, the operative field is limited to the instrument tip, necessitating rotation of the entire instrument and causing consequent tissue compression while reaching around corners. Although flexible endoscopes offer tip steerability to address this limitation, they are more difficult to control and provide fewer and smaller working channels. A middle ground between these instruments-a rigid endoscope that possesses multiple instrument ports (for example, one at the tip and one on the side)-is proposed in this article, and a prototype device is evaluated in the context of a third ventricular colloid cyst resection combined with septostomy. METHODS A prototype neuroendoscope was designed and fabricated to include 2 optical ports, one located at the instrument tip and one located laterally. Each optical port includes its own complementary metal-oxide semiconductor (CMOS) chip camera, light-emitting diode (LED) illumination, and working channels. The tip port incorporates a clear silicone optical window that provides 2 additional features. First, for enhanced safety during tool insertion, instruments can be initially seen inside the window before they extend from the scope tip. Second, the compliant tip can be pressed against tissue to enable visualization even in a blood-filled field. These capabilities were tested in fresh porcine brains. The image quality of the multiport endoscope was evaluated using test targets positioned at clinically relevant distances from each imaging port, comparing it with those of clinical rigid and flexible neuroendoscopes. Human cadaver testing was used to demonstrate third ventricular colloid cyst phantom resection through the tip port and a septostomy performed through the lateral port. To extend its utility in the treatment of periventricular tumors using MR-guided laser therapy, the device was designed to be MR compatible. Its functionality and compatibility inside a 3-T clinical scanner were also tested in a brain from a freshly euthanized female pig. RESULTS Testing in porcine brains confirmed the multiport endoscope's ability to visualize tissue in a blood-filled field and to operate inside a 3-T MRI scanner. Cadaver testing confirmed the device's utility in operating through both of its ports and performing combined third ventricular colloid cyst resection and septostomy with an endoscope rotation of less than 5°. CONCLUSIONS The proposed design provides freedom in selecting both the number and orientation of imaging and instrument ports, which can be customized for each ventricular pathological entity. The lightweight, easily manipulated device can provide added steerability while reducing the potential for the serious brain distortion that happens with rigid endoscope navigation. This capability would be particularly valuable in treating hydrocephalus, both primary and secondary (due to tumors, cysts, and so forth). Magnetic resonance compatibility can aid in endoscope-assisted ventricular aqueductal plasty and stenting, the management of multiloculated complex hydrocephalus, and postinflammatory hydrocephalus in which scarring obscures the ventricular anatomy.

Interpretation of atomic friction experiments based on atomistic simulations

Atomic stick-slip experiments on the KBr(100) surface are analyzed using classical zero temperature atomistic simulations. Three different tip models exhibiting atomic stick-slip movement are studied in comparison with the experimental data and the Tomlinson model. The implications of a compliant tip apex for the stick-slip process and the dissipation pathways are discussed.

Hearing aid with a flexible shell

A hearing aid assembled from three sections includes a first section having a first housing containing a microphone and electronics, a second section having a second housing containing a battery, a flex circuit mounted around the battery and a third section having a compliant tip and a receiver contained within a receptacle in the tip. The flex circuit provides solderless electrical connections among the electrical components of the hearing aid. The hearing aid also includes an actuator switch that allows the user to engage the hearing aid in an ON or an OFF mode of operation. Preferably, the actuator is electrically connected to the hearing aid without the use of solder. Connection between the first and second sections includes a mechanical securing mechanism, such as an interlocking joint.

A compliant tip reduces the peak pressure of laparoscopic graspers.

Previous studies have demonstrated that high pressures are generated at the tips of laparoscopic graspers, which can cause tissue injury. This study examines the effect of a compliant edge on tip pressure. One of a pair of identical laparoscopic graspers was modified by refashioning the tip out of silicone. A thin film pressure transducer (I-scan 6900 sensor) was deployed between the jaws of the grasper and a simulated tissue (leather strap). Load and handle pressures were kept constant. Peak tip pressure readings were taken as the load orientation was increased from the perpendicular to 135 degrees (n = 10). The data was analysed using anova and a post-hoc Duncan's multiple range test. Peak tip pressures generated by the compliant tipped grasper were significantly less than those developed by the unmodified grasper, particularly at high-load orientations. High pressures generated at the tip of laparoscopic graspers can be reduced by altering the mechanical properties (compliance) of the tip.