January/February 2002
Volume Two - Issue One

ICES PROJECT HIGHLIGHTS

BIOMEDICAL ENGINEERING AT ICES
ICES is a significant contributor to biomedical and health engineering research and education at CMU. ICES is currently supporting six biomedical engineering projects in 2002. These projects leverage CMU competencies in bone-tissue engineering, robotics, information technology and microelectromechanical systems (MEMS). Biomedical engineering projects include: robotically guided endoscopes; tissue engineered nerve guides; angiogenesis in tissue engineering bone constructs; implantable telemetry based MEMS bone sensors; coating of microparticles for controlled drug delivery; computer-aided orthopedic surgery and context aware computing in medical body monitors.

Robotically Guided Endoscopes
Robotically guided endoscopes promise to overcome these drawbacks of existing urological endoscopes. This research project is a collaborative effort between Carnegie Mellon University and the Children's Hospital of Pittsburgh. The tip of a robotic endoscope is equipped with sensors that are capable of identifying the lumen of the urethra or the ureter. Using this sensory feedback (instead of limited visual information) the endoscope tip can be continuously adjusted to point in the direction of the lumen. The endoscope can, therefore be advanced faster, causing less discomfort and a reducing the potential for tissue injuries associated with endoscopic procedures.

Tissue Engineered Nerve Guides
ICES researchers are pursuing new strategies to repair nerve injuries, such as spinal cord injury. This research involves seeding biodegradable scaffolds with donor cells and growth factors, in this case a nerve guide, then implanting the tubes to induce and direct the growth of new, healthy nerve tissue. If successful, this technology will replace existing treatments for peripheral nerve regeneration including autograft as well as surgical realignment of the severed ends.

Angiogenesis in Tissue Engineering Bone Constructs
ICES is also evaluating techniques for implanting biodegradable scaffolds seeded with cells and/or signaling molecules into bone defect sites to induce and direct the growth of new healthy bone. Cells that are delivered with the scaffolds to the defect sites or cells that migrate into the implanted scaffolds from surrounding healthy tissue need timely access to a vascular supply. This research is exploring new ways to create vasculature within scaffolds and defects (angiogenesis) in a timely, organized, and safe fashion.

Implantable Telemetry Based MEMS Bone Sensors
Research is also being conducted on bone sensors to detect in vivo bone stress via a wireless RF interface. The sensor is envisioned to be a 2mm by 2 mm by 300mm silicon CMOS chip with no external wires. Such a size is minimally invasive, as it is smaller than typical screws used in setting bone fractures. Stress is detected using embedded piezoresistive strain gages made from the CMOS gate polysilicon layer. The chip surface will be textured with appropriate feature sizing to optimize attachment of bone tissue. Several kinds of texture will be explored including parallel ridges, dimpled surfaces and pimpled surfaces, all with varying micron-scale pitch and depth of the features. Chips will be covered with a titanium outer layer for biocompatibility. An initial set of experiments to verify biocompatibility and to measure tissue adherence will be performed by implanting samples in lab rats. The long-term goal is to integrate implantable bone sensors with companion development of a tetherless RF interface, which transmits the stress information and receives power from an external RF source.

Computer-aided Orthopedic Surgery
ICES researchers are also pioneering Computer-Aided-Surgery (CAS) techniques. CAS techniques are emerging methodologies that help surgeons improve outcomes of their procedures by allowing them to optimally preplan surgical procedures in a virtual environment. CAS further allows them to precisely execute their plans during the actual surgery. While CAS is applicable to a broad range of surgical specialties, CAS is particularly well suited to facilitating and improving the outcomes of osteotomy procedures for orthopedic surgery. These procedures are used to reshape a deformed or malaligned bone by cutting the bone so that the remaining mobile segments can be manipulated into the desired shape. This is accomplished with the aid of fixation devices to temporarily stabilize the bone until new bone grows into and across the osteotomy site.

Coating of Microparticles for Controlled Drug Delivery
The localized delivery of growth factors and drugs is important in biomedical applications, in particular for tissue engineering. ICES researchers are, therefore, working to coat biodegradable polymer microspheres with a protective membrane which then allows the drug-containing microspheres to become embedded in tissue-engineered scaffolds.

Context Aware Computing in Medical Body Monitors
ICES researchers are working collaboratively with Body Media to apply context aware computing concepts developed in the Laboratory for Interactive Computing (LINCS) to their medical body monitor. Researchers envision tapping into the sensing power of Body Media's product and applying it to create parameters for understanding a user's computing context. Understanding a users state (i.e., if the user is stressed, nervous, busy or tired) leads to the development of treatments or therapies that meet the unique needs associated with each emotional state.

Simulation-Based Design of Artificial Organs
A major challenge in the field of artificial organ development is understanding the behavior of blood flow. ICES researchers in partnership with researchers from the University of Pittsburgh Medical Center (UPMC) - McGowan Center for Artificial Organ Development, Texas A&M and the University of Washington are working on a project to develop multiscale models of blood flow. Blood flow models will resolve the behavior of blood in complex geometries - from the organ level to the blood cell level. These models will form the basis for simulation-based, next-generation artificial organ design.

The initial project emphasis is on blood flow and artificial heart devices, but algorithms and Lagrangian computational methods developed as a result of this research will provide insight into many other diseases including hypertension, atherosclerosis and thrombosis, sickle cell anemia and stroke.

This multidisciplinary project brings together mathematicians, biochemists, bioengineers, computational fluid dynamicists, computer scientists, hemorheologists, numerical analysts and transplant surgeons and combines Carnegie Mellon University's leadership in interdisciplinary computer/computational sciences with UPMC's world class programs in biological sciences and transplant surgery.

Artificial Lungs
ICES is currently conducting an artificial lung optimization project in collaboration with the Artificial Lung Program and Department of Surgery at UPMC. ICES researchers are performing mathematical modeling, large-scale numerical simulations and predictions as well as some component prototyping whereas researchers at UPMC carry out the in-vitro and animal experimentation. Numerical predictions and optimization enables the development of superior Intravenous Membrane Oxygenator (IMO) devices, known by the lay public as artificial lungs.

The goal of this research is to develop a simulation-based methodology for artificial lung and blood-wetted organ design. The project requires the creation of mathematical models, computational tools and validation by in-vitro experimentation. If successful, optimal design methodologies will lead to the design of artificial organs with improved gas exchange capability, minimal risk of blood trauma and thrombosis. The objective of this research project is to develop methods of improving artificial organ function, greatly improving a recipient's quality of life.

Aortic Aneurysms
Abdominal Aortic Aneurysms (AAAs) are localized balloon-shaped expansions commonly found in the infrarenal segment of the abdominal aorta, between the renal arteries and the iliac bifurcation. Abdominal aortic aneurysm rupture is the 15th leading cause of death in the United States, affecting patients over 55 years of age, typically 2-4% of elderly males. Typical treatment consisting of conservative or surgical management is based on the surgeon's estimation of the risk of rupture vs. mortality and morbidity during surgery combined with the patient's life expectancy. Aneurysm size is often used as the primary indicator of potential rupture by measuring the AAA's maximum diameter. Elective Surgical resection is justified when this diameter exceeds the critical value of 5 cm. It is well known, however, that not all large aneurysms rupture and that aneurysms with a maximum diameter less than the critical value may. Therefore, the criterion results unreliable for the individual patient and there is need for a better assessment of rupture potential.

ICES is assessing the rupture potential of AAA's using computational modeling and simulation, which uses large-scale numerical simulations and modeling based on physiologically realistic measurement obtained during patient diagnosis. The objective of this research is to develop a non-invasive technique for the assessment of aneurysm rupture by integrating the mechanical properties of the artery wall and physiologic blood flow conditions into a unique computational model of aneurysm hemodynamics. This research is being performed in collaboration with Vascular Surgery and Vascular Biomechanics Research Lab of the Section of Vascular Surgery.

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