BME Faculty Research
Nanomaterials for Biomedical Applications (Jan A. Puszynski)
Synthesis, processing, and densification of oxide and nonoxide ceramic materials and intermetallic compounds. Both ceramics and intermetallics have found application as bone replacement materials. Currently, the NSF-sponsored research is focused on in-situ synthesis and densification of nanostructures with controlled porosity and functionally-graded materials, which could find the application as biocompatible materials. In addition, the research is focused on synthesis and processing of magnetic nanoparticles with a specific application into destruction of cancerous cells by RF heating.
Direct Write Technology for Cardiovascular Research (James W. Sears and Stephen Armstrong (USD))
In a cooperative research initiative with the Cardiovascular Research Institute in Sioux Falls (affiliated to University of South Dakota), the Additive Manufacturing Laboratory at the School of Mines is developing conductive silver nano-particle grids in culture dishes for heart-cell simulation research. The conductive grids are deposited via the Direct Write Technology. Each grid is comprised of individual chambers measuring 30 microns by 150 microns. Each grid contains more than 16,000 individual chambers. There are electrical contact pads on the edges of the grid. This project will lead to an acceleration in heart-cell simulation research through the use of these conductive grids.
Direct Write Technology for Tissue Regeneration (James W. Sears and Dan Neufeld (USD))
This is a collaborative research project between the School of Mines and University of South Dakota - Vermillion. The goal of this project is to explore micro-fabrication of idealized matrices to guide cellular behavior and synthesis at the amputation site. Efforts will be directed at the formation of a blastema which may ultimately lead to true appendage regeneration. Direct Write Technologies are to be used to deposit unique scaffolding material (Extra-Cellular Matrix – ECM) doped with the appropriate signal codes to facilitate tissue regeneration.
Polymeric Dental Restorative Composites (Hao Fong)
Dental composites have been available for over four decades. Compared to “dental amalgams”, the composites are safer and possess better aesthetic properties, and therefore have been widely accepted by the dental profession as restorative materials. In general, dental composites have shown relatively satisfactory restorative results. However, dental composites are not yet optimal materials. In particular, (1) the strength and wear property of the composites need to be further improved; and (2) the photopolymerization induced volumetric shrinkage and the concomitant internal stress development need to be further reduced. Dr. Fong’s research in this area is directly targeted on solving the above two problems through (1) design and synthesis of novel methacrylate-based monomers with higher molecular rigidity and longer molecular length, (2) investigation of novel filler materials including electrospun polymer, ceramic carbon/graphite nanofibers, and (3) improvement of filler/matrix interfacial properties by applying innovative surface treatment methods. Dr. Fong has a current National Institutes of Health (NIH)/National Institute of Dental and Craniofacial Research (NIDCR) funding to support his research efforts in this area.
The major equipment Dr. Fong has in this area includes (1) a Mercury Dilatometer (for measuring the photopolymerization induced volumetric shrinkage), (2) a Fourier Transform Infrared Spectrometer (FTIR) with a special near infrared detector (for monitoring the photopolymerization reaction, revealing the reaction kinetics, and measuring the methacrylate double bond conversion), (3) a Universal Mechanical Testing Machine (for measuring the mechanical properties of the prepared materials). In addition, Dr. Fong also has the fully equipped photopolymerization facilities (including various dental monomers, photo-initiators and curing guns/chambers, etc.) and the dental specimen fabrication facilities (including various ASTM standard molds, water-aging chamber, etc.).
Biomedical Application of Electrospun Polymer, Ceramic, and Carbon/Graphite Nanofibers (Hao Fong).
The rapidly developing technology of electrospinning is a unique way to produce polymer, ceramic, and carbon/graphite nanofibers. Unlike conventional fiber spinning techniques that are capable of producing fibers with diameters down to the micrometer range (ca. 5-15 mm), electrospinning is a process capable of producing fibers with diameters down to the nanometer range (ca. 10-1000 nm). In electrospinning, electrostatic force alone is used to drive the process and produce fibers. Polymer nanofibers are electrospun directly from solutions or melts. Ceramic nanofibers are made by electrospinning the sol-gels of their alkoxide precursors, followed by high temperature pyrolysis. Carbon/graphite nanofibers are made through carbonization/graphitization of their polymeric precursors such as polyacrylonitrile (PAN) nanofibers. Dr. Fong’s research is directed towards the systematic investigations of electrospinning in a precisely controlled manner to produce polymer, ceramic, and carbon/graphite nanofibers with desired morphologies, structures and properties.
Biomedical applications are among many potential applications of electrospun nanofibers. Many human tissues and organs including bone, dentin, skin, cartilage and collagen also consist of nano fibrous forms or structures. Electrospun nanofibers are being investigated for various biomedical areas including medical prostheses, tissue engineering, wound dressing, and drug delivery.
Intelligent Signal Processing (John Weiss, Brian Hemmelman, Nian Zhang)
Current research funding from the Army Research Laboratory (contracting through a local company, Realtronics Corporation) is addressing the analysis of radar signals to perform feature extraction and pattern recognition using signal processing algorithms and artificial neural networks. This work is being extended to biomedical applications with another local company, Rapid Medical Systems, to perform computationally intelligent signal analysis on various biomedical signals such as ECG and EEG. Additional neural and fuzzy signal processing and pattern recognition techniques are being developed and applied to medical imaging.
Fault Tolerant Computing (Brian Hemmelman)
Assistive and rehabilitation technologies that involved electronics and computer systems must be reliable and safe. Fault tolerant signal processing and fault tolerant control system architectures are currently being developed in Field Programmable Gate Arrays (FPGAs). Redundant residue number system signal processors are currently being developed under a NASA Program Initiation Grant for space systems, but the same designs are suitable for biomedical systems. Fuzzy logic and artificial neural network chips are also being developed in FPGAs for control and signal processing (including fault tolerant control and signal processing).
Design and optimization of prosthetic devices (Karim H. Muci)
Hip resurfacing arthroplasty is gaining popularity as a bone-conserving alternative to the conventional total hip arthroplasty (THA) in young, active patients that could potentially outlive a total hip prosthesis. THA requires amputation of the femoral head and neck and entrenchment of the marrow cavity in the proximal femur. Yet, in many patients the damage within the hip is limited only to the joint surfaces. Therefore, hip resurfacing can be a surgical option since it replaces only the diseased cartilage or bone with a surface implant, retaining much of the natural geometry and biomechanics of the hip.
In a normal hip, when a load is transferred to the femur the stress is distributed over the cross-section of the bone. In a conventional resurfacing prosthesis, a femoral shell with a central stem that is many times stiffer than the bone is inserted into the femur head and neck. This results in an unequal sharing of the load creating the risk of stress shielding in some areas and stress concentration in others. In particular, significant stress concentration around the base of the femoral component may be found which could lead to atrophy and resorption causing loosening or fracture of the femoral neck.
The design of a new surface hip replacement that utilizes the natural geometry of the femur to secure the component will be considered. As part of the development process, the Finite Element Method (FEM) will be used to analyze the femoral component attached to a three-dimensional model of the femur and the results will be compared against the predicted stress distribution for the same femur model without the implant.
Adaptive Optics for Optometry and Ophthalmology (Umesh A. Korde)
The School of Mines currently is developing an adaptive optics application for the Air Force Research Lab using existing M3D Direct Write technology. Using a small number of direct-written, strategically placed actuators, a low-cost deformable mirror based system will be developed, and used in a feedback loop quantitatively and smoothly to detect flaws in a person’s vision due to corneal defects. The same mirrors could also be used for retinal imaging to enable early detection of retinal defects such as would arise from AMD. Sensitive and reliable diagnosis requires high actuation resolution and fine spatial control over the mirror surface, and a part of the goal of this project will be to investigate optimal control methods to maximize these attributes for the above hardware.
Next Generation Contact Lenses (Umesh A. Korde)
Corneal defects such as defocus, astigmatism, and coma will be quantified using the approach above, and fed to an algorithm for custom lens design. The lenses will be fabricated with engineered corneal tissue material using the n-Scrypt system. This project will integrate into and complement ongoing work for the AFRL which includes the development of biomimetic lenses for adaptive optics applications. Additional investigations will include active control of elasticity and certain optical properties to enable adaptive behavior on part of the lenses.
Assistive Technology Applications
Additional assistive technology projects have been carried out at the MS and senior design level for several years. Topics addressed include speech recognition, medical imaging and signal processing, prosthetic device development, computational analysis of bones, etc.
