Adam L. Cohen

Percutaneous intracardiac beating-heart surgery using metal MEMS tissue approximation tools

Achieving superior outcomes through the use of robots in medical applications requires an integrated approach to the design of the robot, tooling and the procedure itself. In this paper, this approach is applied to develop a robotic technique for closing abnormal communication between the atria of the heart. The goal is to achieve the efficacy of surgical closure as performed on a stopped, open heart with the reduced risk and trauma of a beating-heart catheter-based procedure. In the proposed approach, a concentric tube robot is used to percutaneously access the right atrium and deploy a tissue approximation device. The device is constructed using a metal microelectromechanical system (MEMS) fabrication process and is designed to both fit the manipulation capabilities of the robot as well as to reproduce the beneficial features of surgical closure by suture. The effectiveness of the approach is demonstrated through ex vivo and in vivo experiments.

Percutaneous Steerable Robotic Tool Delivery Platform and Metal MEMS Device for Tissue Manipulation and Approximation: Closure of Patent Foramen Ovale in an Animal Model

Background—Beating-heart image-guided intracardiac interventions have been evolving rapidly. To extend the domain of catheter-based and transcardiac interventions into reconstructive surgery, a new robotic tool delivery platform and a tissue approximation device have been developed. Initial results using these tools to perform patent foramen ovale closure are described. Methods and Results—A robotic tool delivery platform comprising superelastic metal tubes provides the capability of delivering and manipulating tools and devices inside the beating heart. A new device technology is also presented that uses a metal-based microelectromechanical systems–manufacturing process to produce fully assembled and fully functional millimeter-scale tools. As a demonstration of both technologies, patent foramen ovale creation and closure was performed in a swine model. In the first group of animals (n=10), a preliminary study was performed. The procedural technique was validated with a transcardiac hand-held delivery platform and epicardial echocardiography, video-assisted cardioscopy, and fluoroscopy. In the second group (n=9), the procedure was performed percutaneously using the robotic tool delivery platform under epicardial echocardiography and fluoroscopy imaging. All patent foramen ovales were completely closed in the first group. In the second group, the patent foramen ovale was not successfully created in 1 animal, and the defects were completely closed in 6 of the 8 remaining animals. Conclusions—In contrast to existing robotic catheter technologies, the robotic tool delivery platform uses a combination of stiffness and active steerability along its length to provide the positioning accuracy and force-application capability necessary for tissue manipulation. In combination with a microelectromechanical systems tool technology, it can enable reconstructive procedures inside the beating heart.

Metal MEMS tools for beating-heart tissue approximation

Achieving superior outcomes through the use of robots in medical applications requires an integrated approach to the design of the robot, tooling and the procedure itself. In this paper, this approach is applied to develop a robotic technique for closing abnormal communication between the atria of the heart. The goal is to achieve the efficacy of surgical closure as performed on a stopped, open heart with the reduced risk and trauma of a beating-heart catheter-based procedure. In the proposed approach, a concentric tube robot is used to percutaneously access the right atrium and deploy a tissue approximation device. The device is constructed using a metal MEMS fabrication process and is designed to both fit the manipulation capabilities of the robot as well as to reproduce the beneficial features of surgical closure by suture. Experimental results demonstrate device efficacy through manual in-vivo deployment and bench-top robotic deployment.

Microscale metal additive manufacturing of multi‐component medical devices

Purpose – The purpose of this paper is to familiarize the reader with the capabilities of EFAB technology, a unique additive manufacturing process which yields fully assembled, functional mechanisms from metal on the micro to millimeter scale, and applications in medical devices.Design/methodology/approach – The process is based on multi‐layer electrodeposition and planarization of at least two metals: one structural and one sacrificial. After a period of initial commercial development, it was scaled up from a prototyping‐only to a production process, and biocompatible metals were developed for medical applications.Findings – The process yields complex, functional metal micro‐components and mechanisms with tight tolerances from biocompatible metals, in low‐high production volume.Practical implications – The process described has multiple commercial applications, including minimally invasive medical instruments and implants, probes for semiconductor testing, military fuzing and inertial sensing devices, mi...

Monolithic 3-D Microfabrication of Mechanisms With Multiple Independently-Moving Parts

Microfabrication technology has matured to the point that sophisticated, highly-miniaturized mechanisms can now routinely be manufactured in a batch process in metal. These mechanisms may include a variety of distinct, individually-moving parts. Through the use of monolithic 3-D fabrication, the need for microscale assembly, normally a major cost barrier to volume production may be eliminated. We present the production of complex mechanisms produced using EFAB technology, a batch production process providing multiple layers of electrodeposited and planarized metals. Complex, integrated systems including hinges, flexures, bearings, gears, and drive chains have been produced. EFAB technology allows intricate mechanisms with features as small as 2 μm and overall sizes in the range of 10s of microns to millimeters to be designed using standard 3-D mechanical CAD tools. Air-driven turbines with roller bearings, self-assembled gear trains with three stages of 2:1 reduction gearing, and a concept demonstration of a modular, multi-functional instrument for minimally-invasive surgery are discussed. The latter device, measuring approximately 1 × 0.5 mm in cross section, uses microscale chains and pulleys to independently extend and retract both a hook-shaped instrument and microscale forceps. The design allows for stacking of additional tool modules as required. Highly-miniaturized instruments such as these can be attached at the end of a catheter and actuated remotely by the surgeon by applying pure tension through cables.Copyright