MENG 471/473 Projects - 2016

In MENG 471/473, students work on independent projects that cover a wide range of topics, from traditional mechanical engineering topics (e.g., mechanical device design, fluid flow, and materials analysis) to interdisciplinary topics at the interface between mechanical engineering and other branches of engineering such as biomedical, chemical, electrical, or environmental engineering. Under the supervision of faculty advisers, students investigate physical phenomena through experimental measurement and/or numerical simulation, and they design and construct functioning prototypes to solve engineering problems. The majority of the faculty advisers come from within the mechanical engineering department, with the remaining advisers distributed across the University (and occasionally outside the University). Funding for projects is generously provided by the Yale SEAS Dean's Office and, in some cases, through the faculty advisers. The students were asked to write the following short summaries two-thirds of the way through the semester, when they still had a few weeks to go on their projects.


Biomechanics Research


Developing a model of human throwing

Petter Wehlin Adviser: Prof. Madhusudhan Venkadesan, Mechanical Engineering and Materials Science

Human throwing abilities are yet to be fully explained. Based on the accuracy and speed with which skilled individuals throw, one can show that they consistently let go of the object during a launch window of about one millisecond. This launch window is much shorter than what nerve impulses can reliably control. Hence, in the Yale Biomechanics and Control Lab, we hypothesize that some other biomechanical mechanism exists that allows humans to throw objects as accurately as we do. Our research focuses around testing this hypothesis through a physical model of a human arm, as well as through theoretical means. Our results could advance our understanding of human throwing, and have potential applications in high-speed throwing robots.



Body orientation stability during maximum-impulse two-legged jumping

Alexander Lee Adviser: Prof. Madhusudhan Venkadesan, Mechanical Engineering and Materials Science

Whenever the body applies a force, there is a difference between the intended and the actual forces. In the case of two-legged jumping, these unintended forces can cause the jumper to rotate in the air, leading to injury upon landing. Preliminary measurements in the Yale Biomechanics and Control Lab indicate that the magnitude of the difference between intended and realized forces during a jump should cause a human jumper to fall for all but the smallest of jumps. The purpose of this project is to test a hypothesis that the mechanics of the pelvis balances the impulse applied by the legs. Our approach for evaluating this hypothesis uses mechanical jumpers and high speed motion capture measurements to assess the role of the pelvis. The accompanying image is a motion capture of the mechanical jumper. The jumper consists of a body (top square), two legs (bottom two squares), and a pelvis (middle triangle). The image is a reconstruction of markers on the jumper, which are tracked at 1000 fps using multiple cameras.




Design


3d-printed headphones

Jessica Alzamora Advisers: Dr. Joseph Zinter and Prof. Corey O’Hern, Mechanical Engineering and Materials Science

This project focuses on creating the next generation of a pair of 3D-printed headphones used in Yale’s MENG 400 Making It class. These headphones are designed as a teaching tool to introduce children and college students to concrete fabrication and prototyping skills. These students will walk away not only understanding the mechanics behind building a pair of headphones but also having learned the skills to fabricate this and similar products. Unlike most teaching projects that are of a “build once” style, this kit will teach the students how to fabricate parts using a variety of materials, 3D printing, laser cutting and other fabrication skills. This semester we will be re-designing the attachment pieces, optimizing the size, and improving the available rotation of the headphones. Up to this point in the semester the major focus of the project has been to understand the nuances of designing with 3D printing in mind, with the goal of producing a part of production quality with a good surface finish, durability, and print time. By the end of the semester we hope to finalize the headphone design, allowing the project to move forward, and to focus on producing the curriculum that will work in tandem with the project.



The electronic stethoscope: Revolutionizing home care

Laina Do Dr. Alyssa Siefert, Center for Biomedical and Interventional Technology and Prof. Corey O’Hern, Mechanical Engineering and Materials Science

Recently, there has been a push to limit face-to-face doctor/patient interactions in order to save both time and money. As a result, we are currently working to create an electronic stethoscope that can accurately test ones’ breath sounds at home. Electronic stethoscopes have already been built, but only to record heart sounds. Therefore, we are going to build off of the design of these previously built stethoscopes, with the main focus of finding a way to amplify the sounds. One design consideration we are working on is the material that the chest piece is made out of. We are going to test a 3D printed chest piece in order to see if the different material will affect the sound quality. By changing the material, we can also lower the cost of the stethoscope. Ideally, we would like to give the device to patients at a minimal cost. Eventually, our device will be able to record the breath sounds into an application on the patient’s smart phone. This application will compare the recorded sound to a pre-existing program containing a normal breath sound. After using our device, patients will know if their lungs are healthy or if they need to go in and see their doctor.



EZ ICE™: Reducing component weight using topology optimization

Dylan Gastel Adviser: Dr. Ahmet Becene, Mechanical Engineering and Materials Science

EZ ICE ™, a Yale startup, has created The 60 Minute Backyard Rink ™, the only backyard ice skating rink that can be assembled in under an hour, with no tools, and on any surface. EZ ICE’s novel and patent pending technology provides an entire kit that snaps together with ease — saving users dozens to hundreds of hours of backbreaking labor and frostbite compared with alternative construction methods. The aim of this project is to minimize the weight of the rink’s components such that the rink can still support the 280 lbs of outward force exerted by the water and ice, so that it can still be manufactured using simple side-action molds without any undercuts. We are using Optistruct’s topology optimization software to minimize material usage based on these constraints. Topology optimization optimizes material distribution within a given design space for a given set of loads and boundary conditions such that the resulting design meets prescribed performance targets. We are inputting these loads and boundary conditions into Optistruct. Then, we will re-CAD the optimized components. We expect the final design to be 10–40% lighter than our current design and to be just as strong and easy to manufacture.



Developing a novel technique for central line placement

Brandon Hudik Advisers: Dr. Joseph Zinter and Prof. Corey O’Hern, Mechanical Engineering and Materials Science

A central line is a catheter that is inserted into a patient’s jugular, subclavian, or femoral vein in order to deliver fluids, blood, and medication. Unfortunately, the Seldinger technique, which is the current standard of care for placing a central line, gives rise to complications that are serious, difficult, and costly to manage and sometimes fatal. Therefore, there is a clinical and economic need for a technology that reduces this complication rate. This semester, our team, consisting of two undergraduate engineering students and a vascular surgeon at Yale-New Haven Hospital (YNHH), is developing Ballistra: a medical device that addresses these needs by allowing physicians to insert the line with one hand, maintain constant ultrasound guidance, and protect the needle tip inside the patient’s body. We are also developing manufacturable parts and implementing quality systems and design controls with the help of a medical device design firm. Also, we are conducting pre-clinical trials that will compare our device directly with the Seldinger technique to collect qualitative and quantitative data that suggest our device is safer, more efficient, and easier to use than the standard of care. Preliminary simulator trials at YNHH have hinted at these advantages. Finally, we will also be further developing our business strategy and regulatory pathways.



Developing an affordable, solar-powered CPAP device for infants in low-resource settings

Jessica Lee Advisers: Dr. Joseph Zinter and Prof. Corey O’Hern, Mechanical Engineering and Materials Science

Continuous positive airway pressure (CPAP) devices are used as a therapy for neonatal respiratory distress syndrome (RDS), a leading cause of respiratory failure and mortality in infants in the developing world. Traditional devices in the developed world can cost several thousand dollars, making them inaccessible in low-resource settings. Dr. Ryan Carroll and the Consortium for Affordable Medical Technology at Massachusetts General Hospital have developed a low-cost CPAP prototype for hospitals in Mbarara, Uganda, but the device runs on wall power. Since the region has inconsistent power, with outages nearly every week, we are working to build an affordable CPAP device that is powered by a solar-rechargeable battery. During the semester, we will develop the CPAP circuit outlined in the diagram. We have examined several device designs and pumps to ensure affordability, robustness, low power, and ease of use. Next, we will develop the battery-solar system to show that the device can run at clinical standards on a rechargeable battery. Next semester, we will continue to optimize the solar-recharging system for hospital-wide infrastructure.



Developing an automated system for Multiplex Automated Genome Engineering (MAGE)

Benjamin Rosenbluth Adviser: Prof. Farren Isaacs, Molecular, Cellular, and Developmental Biology

Multiplex Automated Genome Engineering (MAGE) is a genetic engineering technique designed to cultivate genomically diverse e. coli populations with broad applications spanning scientific discovery, drug development and industry. Despite its conception as an automated technique, MAGE in its current practice is performed laboriously by hand. Our research aims to build a scalable system to automate the MAGE process to meet growing academic and industrial demand for genetically engineered organisms. The device built at this stage is a flexible turbidostat, a brand of bioreactor that will form a closed loop with a genome editor as part of a two-part automated MAGE system. The turbidostat maintains an active cell culture at constant growth conditions by using feedback control system consisting of laser sensors, custom syringe pumps, and heating elements to maintain optical density and temperature. Cultures are grown in modular growth chambers to allow for easy scalability. We will use this device as a platform on which to develop a fully automated genome editor in the spring to provide academic and industrial research facilities with access to automated genome-editing capabilities.




Materials


Nanopatterning polymers with thermoplastic forming

Saisneha Koppaka Adviser: Prof. Jan Schroers, Mechanical Engineering and Materials Science

The longevity of medical implants can be extended by carefully orchestrating the foreign body response (FBR) through nanopatterning. Nanopatterning is a process for generating surface features, such as rods or pores, on the nanometer length scale. One biomaterial that offers excellent processing capabilities for forming these nanoscale patterns is polymers. With this project, we optimize a protocol for nanopatterning polymeric substrates via a type of compression molding process known as thermoplastic forming. By heating a material to its glass-transition temperature and then using a compressive force to press the material into nano-scale porous molds, we form the nanorods on polymer substrates. Tuning the shape of the polymer nanorod, as shown in the accompanying scanning electron microscopy image, is still a work in progress. By the end of the semester, we aim to characterize the optimal processing conditions of a range of polymers to determine which temperature and pressure conditions yield a uniform arrays rods of desired morphology. We hope that the successful fabrication of polymer nanorods can have important applications in the field of nanofabrication and biomedical engineering.



Nano- and micro-patterning bulk metallic glass for biomedical applications

Jennie Wang Adviser: Prof. Jan Schroers, Mechanical Engineering and Materials Science

Research shows that cells can respond to patterned topographies with high aspect ratios by eliciting various morphological and behavioral responses, such as contracting, elongating, and secreting particular proteins. In order to investigate cellular responses to combinations of nano- and micro-features, we thermoplastically formed platinum-based metallic glass into different geometries and hierarchies to be plated with cells and analyzed for resulting changes. By applying a compressive force and heat to a layered setup with the metallic glass and patterned templates with nano- and micro-features such that the material will flow like a liquid into the molds, we were able to form the metallic glass into desired shapes. Pictured is a hierarchically patterned sample with 1 μm micro-pillars and 55 nm-diameter nanorods on top. The plated cell seems to be sensing the nano-topography of the substrate, causing it to elongate and spread over the area of two micro-pillars. Understanding the effect of different topographies on cell behavior would allow us to strategically pattern biomedical devices and implants to avoid foreign body rejection. We hope to fabricate and examine the effects of other hierarchical geometries to further characterize the realm of effects and identify the critical length scale for desired cellular responses.