Our research group focuses in the development of innovative biomedical devices and the study of human dynamics and neuromuscular control. Research projects are slanted toward commercial applications with most projects having elements of designing, building, and testing. Some projects are focused on developing new medical devices, while others are focused on optimizing engineering designs for improved manufacturability. A few of our current projects are shown below.
Design for Manufacturing
Topology Optimization in 3D Metal Printing: Direct Metal Laser Sintering (DMLS) is a new technology that can be utilized to create structures that cannot be produced by traditional machining processes. Unlike traditional subtractive manufacturing that removes material to produce a component, additive manufacturing produces parts by adding successive layers. In subtractive manufacturing, cost of a part increases with the amount of material removed due to increased labor time. There is a tradeoff between part cost and part weight. The opposite is true for additive manufacturing – the reducing part weight reduces raw material cost, labor cost, processing time, and weight. As a result, employing topology optimization methods to reduce part weight also reduces cost. Jeremy Smith successfully defended his thesis to use ANSYS finite elements analysis (FEA) and topology optimization software to optimize the design of a 3D metal printed bicycle crank arm. He also employed Design for Metal additive manufacturing guidelines to improve the manufacturability of the design prior to printing. Overall, he achieved a 41% weight reduction and associated cost savings with the new design while maintaining the components ability to carry a load.
Controlling Material Properties using Mesostructures: Terail Conts is designing “materials” in which the elastic modulus can be adjusted. This is being achieved by 3D printing mesostructures within the material. These meso structures are smaller that the overall size of the part so overall part shapes can be achieved. However, they are larger than the microstructure, material grains visible using a microscope. Mesostructures are typically on the order of 0.1 mm to 1.5 mm in size. Unlike foam metal that has a random mesostructure, the mesostructure created by 3D printing can be designed enabling more control of material properties. One application of this research is to enable the ability to create an orthopaedic implant with an elastic modulus that matches that of bone to avoid stress shielding. Moreover, because the material stiffness can be adjusted throughout the structure, areas of higher stress can be stiffened and other areas can be made more compliant.
Medical Device Design
Neural Prosthesis: The latest generation of prosthesis include intelligent artificial controllers that enhance the performance of the prosthesis. We are working with the department of physical therapy to developing an experimental medical device to improve gait in people with muscle weakness associated with spinal cord injury, multiple sclerosis, muscular dystrophy, etc. The device under development by Premkumar Subbukutti uses artificial electrical stimulation to induce contractions in the muscles of the lower leg increasing the push off force while walking. Data from foot pressure sensors, accelerometers, and gyroscopes attached to the body are used by the onboard computer within the device to properly time muscle stimulations. We are developing neural networks to manage the large amount of data collected during the decision process.
Biofeedback Device for Stroke Rehabilitation: We are also developing another device to provide positive biofeedback to people during stroke rehabilitation gait retraining. The device is being developed by undergraduate student Jazz Click. The third generation of the device includes a Arduino Nano microcontroller, foot pressure sensor, microphone, and lithium batteries. During gait retraining, when the patient’s heel strikes the ground (as desired) a positive tone is emitted from the device providing biofeedback to reinforce the motion.