A handheld, portable cranial drilling tool for safely creating holes in the skull without damaging brain tissue is presented. Such a device is essential for neurosurgeons and mid-level practitioners treating patients with traumatic brain injury. A typical procedure creates a small hole for inserting sensors to monitor intra-cranial pressure measurements and/or removing excess fluid. Drilling holes in emergency settings with existing tools is difficult and dangerous due to the risk of a drill bit unintentionally plunging into brain tissue. Cranial perforators, which counter-bore holes and automatically stop upon skull penetration, do exist but are limited to large diameter hole size and an operating room environment. The tool presented here is compatible with a large range of bit diameters and provides safe, reliable access. This is accomplished through a dynamic bi-stable linkage that supports drilling when force is applied against the skull but retracts upon penetration when the reaction force is diminished. Retraction is achieved when centrifugal forces from rotating masses overpower the axial forces, thus changing the state of the bi-stable mechanism. Initial testing on ex-vivo animal structures has demonstrated that the device can withdraw the drill bit in sufficient time to eliminate the risk of soft tissue damage. Ease of use and portability of the device will enable its use in unregulated environments such as hospital emergency rooms and emergency disaster relief areas.
The small scale of minimally-invasive surgery (MIS) presents significant challenges to developing robust, smart, and dexterous tools for manipulating millimeter and sub-millimeter anatomical structures (vessels, nerves) and surgical equipment (sutures, staples). Robotic MIS systems offer the potential to transform this medical field by enabling precise repair of these miniature tissue structures through the use of teleoperation and haptic feedback. However, this effort is currently limited by the inability to make robust and accurate MIS end effectors with integrated force and contact sensing. In this paper, we demonstrate the use of the novel Pop-Up Book MEMS manufacturing method to fabricate the mechanical and sensing elements of an instrumented MIS grasper. A custom thin-foil strain gage was manufactured in parallel with the mechanical components of the grasper to realize a fully-integrated electromechanical system in a single manufacturing step, removing the need for manual assembly, bonding and alignment. In preliminary experiments, the integrated grasper is capable of resolving forces as low as 30 mN, with a sensitivity of approximately 408 mV/N. This level of performance will enable robotic surgical systems that can handle delicate tissue structures and perform dexterous procedures through the use of haptic feedback guidance.
Innovation in patient care requires both clinical and technical skills, and this paper presents the methods and outcomes of a nine-year, clinical-academic collaboration to develop and evaluate new medical device technologies, while teaching mechanical engineering. Together, over the course of a single semester, seniors, graduate students, and clinicians conceive, design, build, and test proof-of-concept prototypes. Projects initiated in the course have generated intellectual property and peer-reviewed publications, stimulated further research, furthered student and clinician careers, and resulted in technology licenses and start-up ventures.
Up to eight percent of patients develop steal syndrome after prosthetic dialysis access graft placement, which is characterized by low blood flow to the hand. Steal syndrome results in a cold hand, pain, and in extreme cases, loss of function and tissue damage. A practical and easy way of adjusting the fluidic resistance in a graft to attenuate the risk of steal physiology would greatly benefit both surgeons and patients. This paper describes the design and development of a device that can be attached to a dialysis access graft at the time of surgical implantation to enable providers to externally adjust the resistance of the graft postoperatively. Bench level flow experiments and magnetic setups were used to establish design requirements and test prototypes. The Graft Resistance Adjustment Mechanism (GRAM) can be applied to a standard graft before or after it is implanted and a non-contact magnetic coupling enables actuation through the skin for graft compression. The device features a winch-driven system to provide translational movement for a graft compression unit. We expect such a device to enable noninvasive management of steal syndrome in a manner that does not change the existing graft and support technologies, thus reducing patient complications and reducing costs to hospitals.
In this paper, we describe our prototype of an ultrasound guidance system to address the need for an easy-touse, cost-effective, and portable technology to improve ultrasound-guided procedures. The system consists of a lockable, articulating needle guide that attaches to an ultrasound probe and a user-interface that provides real-time visualization of the predicted needle trajectory overlaid on the ultrasound image. Our needle guide ensures proper needle alignment with the ultrasound imaging plane. Moreover, the calculated needle trajectory is superimposed on the real-time ultrasound image, eliminating the need for the practitioner to estimate the target trajectory, and thereby reducing injuries from needle readjustment. Finally, the guide is lockable to prevent needle deviation from the desired trajectory during insertion. This feature will also allow the practitioner to free one hand to complete simple tasks that usually require a second practitioner to perform. Overall, our system eliminates the experience required to develop the fine hand movement and dexterity needed for traditional ultrasound-guided procedures. The system has the potential to increase efficiency, safety, quality, and reduce costs for a wide range of ultrasound-guided procedures. Furthermore, in combination with portable ultrasound machines, this system will enable these procedures to be more easily performed by unskilled practitioners in non-ideal situations such as the battlefield and other disaster relief areas.