Biomedical Engineering and Bioengineering Commons^™

Organization And Signal Processing Of The Descending Tracts In The Cervical Spinal Cord, Yanmei Tie

Doctoral Dissertations

This dissertation addresses the research for the development of spinal cord-computer interface (SCCI). The main objective of SCCI is to generate voluntary motor control signals for individuals with spinal cord injury (SCI).

In the neuroscience aspect, organization of the fibers in the descending tracts of the dorsolateral funiculus of the cervical spinal cord was investigated in cats. The spinal cord was penetrated with silicon substrate microelectrodes at 400 μm intervals in the medio-lateral direction at the C5/C6 and C6/C7 segmental borders. The stimulus consisted of a 20 ms train of charge-balanced biphasic pulses at 330 Hz. The evoked activities from …

Numerical Simulation Of Nanopulse Penetration Of Biological Matter Using The Z -Transform, Shengjun Su

Doctoral Dissertations

Short duration, fast rise time ultra-wide-band (UWB) electromagnetic pulses (“nanopulses”) are generated by numerous electronic devices in use today. Moreover, many novel technologies involving nanopulses are under development and expected to become widely used soon. Study of nanopulse bioeffects is needed to probe their useful range in possible biomedical and biotechnological applications, and to ensure human safety.

Based on the well-known dispersive properties of biological matter and their expression as a summation of terms corresponding to the main polarization mechanisms, the Cole-Cole expression is commonly employed to describe the frequency dependence of the dielectric properties of a tissue. Solving the …

Biosensing With Microcantilever-Based Sensors, Xiaodong Yan

Doctoral Dissertations

Microcantilevers provide an ideal platform for biosensors. The micron-sized transducer brings several advantages, such as high sensitivity, small sample quantity for analysis, portability, implantable sensor devices, and the ability to be mass produced and integrated into standard microelectronic processing technologies like complementary metal oxide seminconductors (CMOS).

The objective of this research is to investigate and develop modification methods of microcanitlevers for biosensing applications.

Two microcantilever modification methods were investigated. They are self-assembly monolayer method and layer-by-layer method. A fundamental procedure for modification of microcantilevers using the layer-by-layer approach was developed for the first time in this research. These modification methods …

Dilation Of The Oropharynx Via Selective Stimulation Of The Hypoglossal Nerve, Jingtao Huang

Doctoral Dissertations

Obstructive sleep apnea (OSA) is caused by the retraction of the tongue to occlude the upper airway (UAW). Electrical stimulation of the tongue protrudor and retractor muscle has been demonstrated as an effective technique to alleviate UAW obstructions and is considered to be a potential treatment for OSA. Recent studies have shown that selective stimulation of the hypoglossal nerve (HG) to activate tongue muscles using a single implantable device presents an attractive approach for treating OSA. In this study, the functional outcome of selective hypoglossal nerve stimulation with a multi-contact peripheral nerve electrode was studied by imaging the airway in …

Effects Of Diabetes And Aging On Posture And Acceleration Thresholds During Lateral Translations, Samantha Jean Richerson

Doctoral Dissertations

Research objectives. One source of falls in the elderly may be an inability to sufficiently adjust to transient postural perturbations or slips. Identifying useful predictors of fall potential, as well as factors that affect the ability of an individual to detect a movement of the standing support surface may provide insight into postural stability and methods to increase stability in elders. To do this, acceleration thresholds to short, precise, lateral platform translations and the resultant psychophysical responses of adults with early Type 2 diabetes to age-matched controls and young adults were measured.

Methods. Using an innovative SLIP-FALLS platform, …

Behavior Of Nano-Engineered Platelets In A Coronary Artery Stenosis Model, Hua Ai

Doctoral Dissertations

Cardiovascular disease is the leading cause of death in North America. Cardiac infarction caused by thrombus plaque rupture can often lead to sudden death. Arterial stenosis caused by atherosclerosis is an important precursor leading to thrombus formation. Shear stress, abnormal lipid metabolism, and subendothelial layer exposure are the major contributors to arterial thrombus formation. Platelet activation by the above factors, followed by adhesion is the basic sequence in thrombus formation.

Platelets were encapsulated with nanofilm in order to reduce platelet activation and adhesion under high shear stress. Polyions, nanoparticles and immunoglobulins were assembled in nano-organized shells on fixed bovine platelets …

Role Of Nitric Oxide As A Modulator Of Platelet Dense Granule Release, Clifton Ford Frilot Ii

Doctoral Dissertations

Nitric oxide (NO) has been shown to suppress platelet activation, induce vasodilation, inhibit smooth muscle cell proliferation, and act against infection. Activated platelets generally have opposite effects from these. They secrete platelet-derived growth factor (PDGF), which stimulates smooth muscle growth, serotonin, which is a platelet agonist, and a number of agents that promote further platelet aggregation. However, activated platelets also produce NO through the enzymatic functions of the constitutive form of nitric oxide synthase (NOS). The primary functions of this capability are not yet completely understood. Due to its low molecular weight and high diffusivity, NO is quickly transported from …

Generation Of Oxygen Microbubbles In A Microchannel With Crosscurrent Liquid Flow, Sung Sam Kim

Doctoral Dissertations

An alternative way of blood oxygenation is proposed by introducing small bubbles directly into the blood stream. To be used for blood oxygenation, the bubble should be small enough to pass through the capillary beds. To explore the feasibility of producing small bubbles, bubble formation phenomena in a crosscurrent liquid flow in a silicon microchannel were studied. Small orifices with 4 μm, 4.2 μm, and 6.6 μm hydraulic diameter were machined in a direction perpendicular to a trapezoidal channel that has a hydraulic diameter of 42 micrometers. These orifices were connected to three different chambers of 2.5 × 10−7 cm3, …

Evaluation Of 135- And 150-Degree Sliding Hip Screws, Kelly Blayne Crittenden

Doctoral Dissertations

Sliding hip screws are routinely used to repair Garden III femoral neck factures. This research seeks to better understand the influence of the hip screw angle on the performance of the fixation. The mechanics of fractured femurs repaired with 135- and 150-degree sliding fixation devices are explored using experimental, finite element, and analytical modeling. The experimental study involves testing of both intact and fixated femurs; the finite element work centers on two-dimensional models of intact and fixated femurs; and the analytical modeling explores the forces, moments and stresses in the fixation. The analytical model predicts that the screw will serve …