Smart Medical

2017
T. Ranzani, S. Russo, F. Schwab, C. J. Walsh, and R. J. Wood, “Deployable stabilization mechanisms for endoscopic procedures,” in IEEE International Conference on Robotics and Automation (ICRA), Singapore, 2017.
J. B. Gafford, R. J. Wood, and C. J. Walsh, “A high-force, high-stroke distal robotic add-on for endoscopy,” in IEEE International Conference on Robotics and Automation (ICRA), Singapore, 2017.
2016
J. B. Gafford, F. Doshi-Velez, R. J. Wood, and C. J. Walsh, “Machine learning approaches to environmental disturbance rejection in multi-axis optoelectronic force sensors,” Sensors and Actuators A: Physical, vol. 248, pp. 78 - 87, 2016. Publisher's VersionAbstract

Light-Intensity Modulated (LIM) force sensors are seeing increasing interest in the field of surgical robotics and flexible systems in particular. However, such sensing modalities are notoriously susceptible to ambient effects such as temperature and environmental irradiance which can register as false force readings. We explore machine learning techniques to dynamically compensate for environmental biases that plague multi-axis optoelectronic force sensors. In this work, we fabricate a multisensor: three-axis LIM force sensor with integrated temperature and ambient irradiance sensing manufactured via a monolithic, origami-inspired fabrication process called printed-circuit MEMS. We explore machine learning regression techniques to compensate for temperature and ambient light sensitivity using on-board environmental sensor data. We compare batch-based ridge regression, kernelized regression and support vector techniques to baseline ordinary least-squares estimates to show that on-board environmental monitoring can substantially improve sensor force tracking performance and output stability under variable lighting and large (>100C) thermal gradients. By augmenting the least-squares estimate with nonlinear functions describing both environmental disturbances and cross-axis coupling effects, we can reduce the error in Fx, Fy and Fz by 10%, 33%, and 73%, respectively. We assess viability of each algorithm tested in terms of both prediction accuracy and computational overhead, and analyze kernel-based regression for prediction in the context of online force feedback and haptics applications in surgical robotics. Finally, we suggest future work for fast approximation and prediction using stochastic, sparse kernel techniques.

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T. Ranzani, S. Russo, C. J. Walsh, and R. J. Wood, “A soft pop-up proprioceptive actuator for minimally invasive surgery,” in The 9th Hamlyn Symposium on Medical Robotics, London, England, 2016.
T. Ranzani, S. Russo, C. J. Walsh, and R. J. Wood, “A soft suction-based end effector for endoluminal tissue manipulation,” in The 9th Hamlyn Symposium on Medical Robotics, London, England, 2016.
J. B. Gafford, T. Ranzani, S. Russo, S. B. Kesner, R. J. Wood, and C. J. Walsh, “Toward Medical Devices with integrated Mechanisms, Sensors and Actuators via Printed-Circuit MEMS,” ASME Journal of Medical Devices, vol. 11, no. 1, pp. 011007-011018, 2016. Publisher's VersionAbstract

Recent advances in medical robotics have initiated a transition from rigid serial manipulators to flexible or continuum robots capable of navigating to confined anatomy within the body. A desire for further procedure minimization is a key accelerator for the development of these flexible systems where the end goal is to provide access to the previously inaccessible anatomical workspaces and enable new minimally invasive surgical (MIS) procedures. While sophisticated navigation and control capabilities have been demonstrated for such systems, existing manufacturing approaches have limited the capabilities of millimeter-scale end-effectors for these flexible systems to date and, to achieve next generation highly functional end-effectors for surgical robots, advanced manufacturing approaches are required. We address this challenge by utilizing a disruptive 2D layer-by-layer precision fabrication process (inspired by printed circuit board manufacturing) that can create functional 3D mechanisms by folding 2D layers of materials which may be structural, flexible, adhesive, or conductive. Such an approach enables actuation, sensing, and circuitry to be directly integrated with the articulating features by selecting the appropriate materials during the layer-by-layer manufacturing process. To demonstrate the efficacy of this technology, we use it to fabricate three modular robotic components at the millimeter-scale: (1) sensors, (2) mechanisms, and (3) actuators. These modules could potentially be implemented into transendoscopic systems, enabling bilateral grasping, retraction and cutting, and could potentially mitigate challenging MIS interventions performed via endoscopy or flexible means. This research lays the ground work for new mechanism, sensor and actuation technologies that can be readily integrated via new millimeter-scale layer-by-layer manufacturing approaches.

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Self-Assembling, Low-Cost, and Modular mm-Scale Force Sensor
J. B. Gafford, R. J. Wood, and C. J. Walsh, “Self-Assembling, Low-Cost, and Modular mm-Scale Force Sensor,” IEEE Sensors Journal, vol. 16, no. 1, pp. 69-76. [Cover Article], 2016. Publisher's VersionAbstract

The innovation in surgical robotics has seen a shift toward flexible systems that can access remote locations inside the body. However, a general reliance on the conventional fabrication techniques ultimately limits the complexity and the sophistication of the distal implementations of such systems, and poses a barrier to further innovation and widespread adoption. In this paper, we present a novel, self-assembling force sensor manufactured using a composite lamination fabrication process, wherein linkages pre-machined in the laminate provide the required degrees-of-freedom and fold patterns to facilitate self-assembly. Using the purely 2-D fabrication techniques, the energy contained within a planar elastic biasing element directly integrated into the laminate is released post-fabrication, allowing the sensor to self-assemble into its final 3-D shape. The sensors are batch-fabricated, further driving down the production costs. The transduction mechanism relies on the principle of light intensity modulation, which allows the sensor to detect axial forces with millinewton-level resolution. The geometry of the sensor was selected based on the size constraints inherent in minimally invasive surgery, as well as with a specific focus on optimizing the sensor's linearity. The sensor is unique from the fiber-based force sensors in that the emitter and the detector are encapsulated within the sensor itself. The bare sensor operates over a force range of 0-200 mN, with a sensitivity of 5 V/N and a resolution of 0.8 mN. The experimental results show that the sensor's stiffness can be tuned using a thicker material for the spring layer and/or encapsulation/integration with soft materials. The empirical validation shows that the sensor has the sensitivity and the resolution necessary to discern the biologically relevant forces in a simulated cannulation task.

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J. B. Gafford, S. Russo, T. Ranzani, R. J. Wood, and C. J. Walsh, “Snap-On Robotic Wrist Module for Enhanced Dexterity in Endoscopy,” in IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden, 2016. PDF
S. Russo, T. Ranzani, J. B. Gafford, C. J. Walsh, and R. J. Wood, “Soft pop-up mechanisms for micro surgical tools: design and characterization of compliant millimeter-scale articulated structures,” in IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden, 2016. PDF
2015
A Light-Reflecting Balloon Catheter for Atraumatic Tissue Defect Repair
E. T. Roche, et al., “A Light-Reflecting Balloon Catheter for Atraumatic Tissue Defect Repair,” Science Translational Medicine, vol. 7, no. 306, pp. 306ra149, 2015. Publisher's VersionAbstract

Closing small defects in the body typically requires stitching of tissues during surgery. Toward a minimally invasive approach, Roche et al. engineered a balloon catheter with a reflective surface coating that could be used to adhere biodegradable patches to tissues. The device unfolds the patch and its adhesive, delivers ultraviolet (UV) light, and then applies pressure to stabilize the adhesive as the light cures the polymer. The authors demonstrated catheter-mediated application of the photocurable polymer patch in vivo in rat tissue, with minimal inflammation and complete animal survival, as well as in a challenging septal defect in the beating hearts of pigs. The device was also used to seal porcine stomach ulcers and abdominal hernias ex vivo, suggesting versatility of this approach in repairing defects more easily and atraumatically than sutures.A congenital or iatrogenic tissue defect often requires closure by open surgery or metallic components that can erode tissue. Biodegradable, hydrophobic light-activated adhesives represent an attractive alternative to sutures, but lack a specifically designed minimally invasive delivery tool, which limits their clinical translation. We developed a multifunctional, catheter-based technology with no implantable rigid components that functions by unfolding an adhesive-loaded elastic patch and deploying a double-balloon design to stabilize and apply pressure to the patch against the tissue defect site. The device uses a fiber-optic system and reflective metallic coating to uniformly disperse ultraviolet light for adhesive activation. Using this device, we demonstrate closure on the distal side of a defect in porcine abdominal wall, stomach, and heart tissue ex vivo. The catheter was further evaluated as a potential tool for tissue closure in vivo in rat heart and abdomen and as a perventricular tool for closure of a challenging cardiac septal defect in a large animal (porcine) model. Patches attached to the heart and abdominal wall with the device showed similar inflammatory response as sutures, with 100% small animal survival, indicating safety. In the large animal model, a ventricular septal defect in a beating heart was reduced to <1.6 mm. This new therapeutic platform has utility in a range of clinical scenarios that warrant minimally invasive and atraumatic repair of hard-to-reach defects.

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W. Whyte, E. T. Roche, H. O'Neill, G. Duffy, C. J. Walsh, and D. J. Mooney, “A Replenishable Cell Delivery System for the Heart,” in 4th TERMIS World Congress, Boston, MA, 2015.
J. Gafford, R. J. Wood, and C. J. Walsh, “Robust, low-cost, modular mm-scale distal force sensors for flexible robotic platforms,” in Proceedings of the 5th Annual Hamlyn Symposium on Medical Robotics, London, UK, 2015. PDF
R. Malka, et al., “An Access-closure Device for Percutaneous Beating Heart Surgery,” in ASME Design of Medical Devices Conference, Minneapolis, MN, 2015.
J. Gafford, et al., “Shape Deposition Manufacturing of a Soft, Atraumatic, Deployable Surgical Grasper,” ASME Journal of Mechanisms and Robotics, Special Issue: Fabrication of Fully Integrated Robotic Mechanisms, vol. 7, no. 2, pp. 021006-021006-11, 2015. Publisher's VersionAbstract

This paper details the design, analysis, fabrication, and validation of a deployable, atraumatic grasper intended for retraction and manipulation tasks in manual and robotic minimally invasive surgical (MIS) procedures. Fabricated using a combination of shape deposition manufacturing (SDM) and 3D printing, the device (which acts as a deployable end-effector for robotic platforms) has the potential to reduce the risk of intraoperative hemorrhage by providing a soft, compliant interface between delicate tissue structures and the metal laparoscopic forceps and graspers that are currently used to manipulate and retract these structures on an ad hoc basis. This paper introduces a general analytical framework for designing SDM fingers where the desire is to predict the shape and the transmission ratio, and this framework was used to design a multijointed grasper that relies on geometric trapping to manipulate tissue, rather than friction or pinching, to provide a safe, stable, adaptive, and conformable means for manipulation. Passive structural compliance, coupled with active grip force monitoring enabled by embedded pressure sensors, helps to reduce the cognitive load on the surgeon. Initial manipulation tasks in a simulated environment have demonstrated that the device can be deployed though a 15 mm trocar and develop a stable grasp using Intuitive Surgical's daVinci robotic platform to deftly manipulate a tissue analog.

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J. Bae, et al., “A Soft, Wearable, Quantitative Ankle Diagnostic Device,” in ASME Design of Medical Devices Conference, Minneapolis, MN, 2015.
2014
M. Torabi, R. Gupta, and C. J. Walsh, “Compact Robotically Steerable Image-Guided Instrument for Multi-Adjacent-Point (MAP) Targeting,” IEEE Transactions on Robotics, vol. 30, no. 4, pp. 802-815, 2014. Publisher's VersionAbstract

Accurately targeting multi-adjacent points (MAPs) during image-guided percutaneous procedures is challenging due to needle deflection and misalignment. The associated errors can result in inadequate treatment of cancer in the case of prostate brachytherapy, or inaccurate diagnosis during biopsy, while repeated insertions increase procedure time, radiation dose, and complications. To address these challenges, we present an image-guided robotic system capable of MAP targeting of irregularly shaped volumes after a single insertion of a percutaneous instrument. The design of the compact CT-compatible drive mechanism is based on a nested screw and screw-spline combination that actuates a straight outer cannula and a curved inner stylet that can be repeatedly straightened when retracted inside the cannula. The stylet translation and cannula rotation/translation enable a 3-D workspace to be reached with the stylet's tip. A closed-form inverse kinematics and image-to-robot registration are implemented in an image-guided system including a point-and-click user interface. The complete system is successfully evaluated with a phantom under a Siemens Definition Flash CT scanner. We demonstrate that the system is capable of MAP targeting for a 2-D shape of the letter “H” and a 3-D helical pattern with an average targeting error of 2.41 mm. These results highlight the benefit and efficacy of the proposed robotic system in seed placement during image-guided brachytherapy.

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P. Aubin, K. Petersen, H. Sallum, C. J. Walsh, A. Correia, and L. Stirling, “A pediatric robotic thumb exoskeleton for at-home rehabilitation : The isolated orthosis for thumb actuation (IOTA),” International Journal of Intelligent Computing and Cybernetics, vol. 7, no. 3, pp. 233-252. [2015 Award for Outstanding Paper], 2014. Publisher's Version PDF
J. Gafford, A. Degirmenci, S. Kesner, R. J. Wood, R. Howe, and C. J. Walsh, “A Monolithic Approach to Fabricating Low-Cost, Millimeter-Scale Multi-Axis Force Sensors for Minimally-Invasive Surgery,” in Inter. Conf. on Robotics and Automation (ICRA), Hong Kong, China, 2014, pp. 1419-1425. Publisher's VersionAbstract

In this paper we have rapidly prototyped customized, highly-sensitive, mm-scale multi-axis force sensors for medical applications. Using a composite laminate batch fabrication process with biocompatible constituent materials, we have fabricated a fully-integrated, 10×10 mm three-axis force sensor with up to 5 V/N sensitivity and RMS noise on the order of ~1.6 mN, operational over a range of -500 to 500 mN in the x- and y-axes, and -2.5 to 2.5 N in the z-axis. Custom foil-based strain sensors were fabricated in parallel with the mechanical structure, obviating the need for post-manufacturing alignment and assembly. The sensor and its custom-fabricated signal conditioning circuitry fit within a 1×1×2 cm volume to realize a fully-integrated force transduction platform with potential haptics and control applications in minimally-invasive surgical tools. The form factor, biocompatibility, and cost of the sensor and signal conditioning makes this method ideal for rapid-prototyping low-cost, mm-scale distal force sensors. Sensor performance is validated in a simulated tissue palpation task using a robotic master-slave platform.

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L. Marechal, et al., “Optimal Spatial Design of Non-Invasive Magnetic Field-based Localization Systems,” in Inter. Conf. on Robotics and Automation (ICRA), Hong Kong, China, 2014, pp. 3510-3516. Publisher's VersionAbstract

Magnetic localization systems based on passive permanent magnets (PM) are of great interest due to their ability to provide non-contact sensing and without any power requirement for the PM. Medical procedures such as ventriculostomy can benefit greatly from real-time feedback of the inserted catheter tip. While the effects of the number of sensors on the localization accuracy in such systems has been reported, the spatial design of the sensor layout has been largely overlooked. Here in this paper, a framework for determining an optimal sensor assembly for enhanced localization performance is presented and investigated through numerical simulations and direct experiments. Two approaches are presented: one based on structured grid configuration and the other derived using Genetic Algorithms. Simulation results verified by experiments strongly suggest that the layout of the sensors not only has an effect on the localization accuracy, but also has an effect far more pronounced than improvements brought by increasing the number of sensors.

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E. J. Park, et al., “An Intraventricular Soft Robotic Pulsatile Assist Device For Right Ventricular Heart Failure,” in ASME Design of Medical Devices Conference , Minneapolis, MN, 2014. PDF

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