Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 28). / Endotracheal tube insertion requires the measurement of very low pressure. Currently, there exists no reliable method or device that is integral with the inflation syringe for measuring this pressure. Thus, a device for quickly and easily reading the pressure was created within the syringe currently used to pressurize the tube. This device takes the form of elastomeric bellows. These bellows were analyzed to determine the optimum geometry for the pressures involved in the procedure. Although no closed-form model exists for this analysis, FEA was used to obtain accurate results. Using the optimized bellows, a complete for-manufacturing design was created. This design concept has received much acclaim from the medical community and has great promise in transforming many medical procedures which require such measurement.. / by Samuel C. Duffley. / S.B.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 41). / This thesis discusses the design of a small-business wheelchair that empowers disabled people in developing countries to become entrepreneurs. Disabled people in these countries face tremendous discrimination, making it difficult to find employment and further perpetuating the sentiment that they cannot meaningfully contribute to society. This project attempts to change that, providing disabled people with both mobility and a way to generate an income. It was designed in close collaboration with MobilityCare wheelchair workshop in Arusha, Tanzania and tested by five users in a pilot trial that began in July 2008. Each of the participants was given a small-business wheelchair, business training, and seed money to purchase raw materials. In addition, bank accounts were established at a local wheelchair-accessible bank. The success of this trial proved that the small-business wheelchair is a viable way for people with disabilities to generate an income and improve their livelihoods. Several dissemination strategies have been explored so that wheelchair workshops across the developing world can produce this wheelchair. These include the development of a production manual that will be available online as well as at the next Pan African Wheelchair Association meeting, to be held in 2011. In terms of funding, corporate sponsorship has been determined to be an appropriate way to cover the cost of the wheelchair itself. While microfinance is not currently feasible to fund the start-up costs of each business, it is likely to become more appropriate as it grows and expands its services. / by Natasha Scolnik. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002. / Includes bibliographical references (leaves 119-121). / by Aimee B. Angel. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 94-104). / Rehabilitation of human motor function is an issue of utmost significance affecting millions of Americans. Robot-aided therapy emerged as a promising method to meet the increasing demand for effective rehabilitation services. While robot-aided therapy for upper-extremity provides clinically-proven, efficient rehabilitation, human-interactive robots for lower-extremity therapy have been substantially less successful. Given the labor-intensive nature of conventional, human-administered walking therapy, effective robot-aided assistance is urgently needed. The use of robots and treadmills that may inadvertently suppress the expression of the natural oscillatory dynamics of walking is addressed in this thesis as a possible explanation for the ineffectiveness of robotic walking therapy. To further investigate the natural oscillatory dynamics of walking, the existence and provenance (spinal or central) of a neuro-mechanical oscillator underlying human locomotion was assessed. This oscillator was studied via gait entrainment to periodic mechanical perturbations at the ankle in both treadmill and overground environments. Experiments with unimpaired human subjects provided direct behavioral evidence of the non-negligible contribution to human walking made by a limit-cycle oscillator in the spinal neuro-mechanical periphery. Entrainment was always accompanied by phase-locking so that plantar-flexion perturbations assisted propulsion during ankle 'push-off' while dorsi-flexion perturbations assisted toe-clearance during 'initial swing'. The observed behavior seemed to require a neural adaptation that could not easily be ascribed to biomechanics, suggesting a hierarchical organization between the supra-spinal nervous system and the spinal neuro-mechanical periphery: episodic supervisory control. / by Julieth Ochoa. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995. / Includes bibliographical references (leaf 90). / by Christopher James Shutts. / M.S.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 59-60). / This project involved the design and fabrication of a self-balancing monopedal robot which is intended to be used as a platform for physically validating simulated risk network based control analysis. A precomputed risk network allows a robot to evaluate the risk that an action will lead to an imminent fall or lead to a state from which the robot will eventually fall after several jumps.' The physical implementation of the simulated robot will allow the theoretical boundaries of safety to be validated. If validated, risk matrix analysis will allow a system to be modeled such that the controller can modify control inputs which would lead falls. The results of physical testing will be used to refine the simulated model. The robot was designed to be as simple as possible while still being capable of operating in three dimensions to study hybrid dynamics and underactuated locomotion. A mechanism with a direct kinematic relation to the output along with a static contact area was designed to allow the ground force profiles to be accurately controlled. In order to utilize the risk network, the force applied by the foot as well as the robot's take-off angle and rate of angular rotation at take-off are key parameters which must be measured and controlled. The robot was be optimized to precisely control these parameters rather than to achieve the longest or highest jump possible as is the objective of other studies. / by Evan Brown. / S.B.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 113-118). / Atomically thin materials, and in particular graphene, provide a new class of solid-state nanopores - apertures that allow for the exchange of matter across thin membranes - with the smallest possible volumes of any ion channel. As the diameter of these nanopores becomes comparable to that of hydrated ions, sub-continuum effects have the potential to enable selective transport similar to that observed in biological ion channels. Being substantially thinner than its biological counterparts, the atomic thickness of graphene places it in a new physical regime with ultimate permeance and distinct geometric constraints on atomic interactions. Engineering graphene nanopores with both high permeance and selectivity has major implications for industrial separation processes, including reverse osmosis, nanofiltration, electrodialysis, metal cation separations, and proton exchange membranes. However, phenomenological measurements on the behavior of single sub-2 nm pores have been extremely limited and the mechanisms of ion transport remain unclear. In this thesis, the behaviors of sub-2 nm graphene nanopores are experimentally characterized, and a theoretical model is developed that quantitatively matches many of the observed transport features. Inspired by the patch-clamp method for measuring ion channels, a method is developed for statistically isolating individual graphene nanopores by reducing the graphene area under test. The conductances of sub-2 nm graphene nanopores were found to span two orders of magnitude below that of larger graphene nanopores reported so far. Different graphene pores were found to display distinct trends in cation selectivity, as well as nonlinear ionic transport such as voltage-activated and rectified current-voltage curves. Furthermore, in rare instances, nanopores exhibited real-time voltage gating where the nanopore switches between two states in a voltage-dependent manner. The set of these behaviors are in fact highly reminiscent of biological ion channels and deviate from those of larger solid-state nanopores. A theoretical model consisting of electromigration over an energy landscape defined by ion dehydration and electrostatic interactions was able to accurately model the nonlinear conductance characteristics of graphene nanopores, and provided evidence that voltage gating is consistent with proton or ion binding/unbinding in the vicinity of the nanopore. Switching gears, a new measurement platform was developed that can measure large numbers of graphene nanopores, with the aim of performing high-throughput characterization of an entire distribution of nanopores in a graphene membrane. By developing a method to integrate solid-state nanopores into microfluidic devices, and leveraging active microfluidic components for electrical multiplexing, measurements over multiple solid-state and graphene nanopores in a single device were demonstrated. In conclusion, this study presents experimental insight into the behaviors of a new class of two-dimensional solid-state nanopores and elucidates the mechanisms of ion transport in these structures. The mechanistic understanding of transport is expected to guide the engineering of graphene nanopores with both high permeance and selectivity, and the high-throughput platform for testing graphene nanopores will enable rapid screening of graphene nanopore fabrication methods. / by Tarun Kumar Jain. / Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994. / Includes bibliographical references (leaves 182-187). / by Jeffrey P. Gardner. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 91-94). / Flexible microwires fabricated from conducting polymers have a wide range of potential applications, including smart textiles that incorporate sensing, actuation, and data processing. The development of garments that integrate these functionalities over wide areas (i.e. the human body) requires the production of long, highly conductive, and mechanically robust fibers or microwires. This thesis describes the development of a microwire slicing instrument capable of producing conducting polymer wires with widths as small as a few micrometers and lengths ranging from tens of millimeters to meters. To ensure high conductivity and robustness, the wires are sliced from thin polypyrrole films electrodeposited onto a glassy carbon crucible. Extensive testing was conducted to determine the optimal cutting parameters for producing long, fine wires with cleanly cut edges. This versatile fabrication process has been used to produce free-standing microwires with cross-sections of 2 [micro]m x 3 [micro]m, 20 [micro]m x 20 [micro]m, and 100 [micro]m x 20 [micro]m with lengths of 15 mm, 460 mm, and 1,200 mm, respectively. An electrochemical dynamic mechanical analyzer was used to measure the static and dynamic tensile properties, the strain-resistance relationship, and the electrochemical actuation performance of the microwires. The measured gage factors ranged from 0.4 to 0.7 and are suitable for strain sensing applications. Strains and forces of up to 2.9% and 2.3 mN were recorded during electrochemical actuation in BMIMPF6 . These monofilament microwires may be spun into yarns or braided into 2- and 3- dimensional structures for use as actuators, sensors, micro antennas, and electrical interconnects in smart fabrics. / by Miguel Angel Sáez. / S.M.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references. / The purpose of this research is to design, fabricate and test the electromechanical subsystem of a CNC milling machine kit. Unlike all other CNC kits on the market, the purpose of this kit is to teach students the principles of electro mechanics during its construction and to teach the principles of CNC machining during its operation. The design process and final designs of both the software and electronic subsystems are described and evaluated. The CNC kit is assembled using off-the-shelf, easy-to-use electronic elements. The software is programmed using Matlab, a common and easy to program software system purchased for all students by MIT. The outline for a course in which this kit could be taught is given, including sample code and circuit schematics. / by Dan Lorenc. / S.B.