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Title: WIRELESS COMMUNICATION FOR AN ACTUATED GLOVE FOR HAND REHABILITATION
Creator: Yuan, Ning
Date: 2016, 2016-12
Description: Stroke survivors often experience long-term upper extremity impairment. This can greatly impair activities of daily living. The eXtension...
Show moreStroke survivors often experience long-term upper extremity impairment. This can greatly impair activities of daily living. The eXtension Glove (X-Glove) is a soft robotic device to aid hand therapy. It uses cables serving as external extensor tendons to assist digit extension and control digit flexion. Load cells are located on each motor to detect the force value of fingers. This paper provides a way to add a biofeedback function on the X-Glove and update the microprocessor to a PIC32MX795. So the X-Glove can establish a wireless communication transmit data with terminals, like PC. In order to display the biofeedback, a graphic user-interface is also developed so that therapists can optimize the therapy for each individual patient in real time.
M.S. in Biomedical Engineering, December 2016
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Title: A KINETIC MODEL TO ESTIMATE VASCULAR PERMEABILITY FROM FLUORESCEIN VIDEOANGIOGRAPHY DATA
Creator: Hu, Shaoxian
Date: 2017, 2017-05
Description: Diabetic retinopathy (DR) is a disease affecting the tissue of the retina through hemodynamics and vascular damage that is a side effect of...
Show moreDiabetic retinopathy (DR) is a disease affecting the tissue of the retina through hemodynamics and vascular damage that is a side effect of hyperglycemia. As such, markers of hemodynamic and vascular irregularity have been proposed as potential early indicators of the disease. However, conventional approaches to estimate these conditions are not sensitive enough, leading to indications that are too late, appearing only after irreversible vision problems have occurred. Indicator-dye-dilution tracer kinetic modeling is a decades-old methodology that can be used to quantify blood flow and vascular permeability based on the kinetics of a rapidly injected blood pool imaging agent. The methodology is able to track sensitive hemodynamic changes in stroke and heart disease patients, yet it has never been applied to blood flow and vascular permeability mapping of the retina. The purpose of my Master’s thesis was to adapt those tracer kinetic methods to fluorescein retinal videoangiography data collected in human to map both blood flow and vascular permeability so that in future work, changes in these parameters can be quantified at varying stages of the development of DR. Studies were carried out on simulated data, healthy and diabetic rats, and healthy and diabetic humans. While a robust validation of measures of blood flow and vascular permeability are still required, this first-of-its-kind study exposed many unique complications in applying the kinetic models to human fluorescein videoangiography data. Specifically, eye motion must be accounted for, both detector and fluorescein fluorescence quenching signal saturation must be avoided, and standard use of automatic gain control of imaging exposure should not be used (though corrections were developed for this); rather, data should be collected at a stable exposure throughout a measurement. Solutions were developed for all of these complications that were tested in rat models (optimal data collection in humans is ongoing). In rat study, average vascular permeability in the rat measured by the “extraction fraction”, the extraction fraction in control subject (n=3) 9.4e-4±1.3e-3, is lower than STZ-diabetic subjects (n=3) 5.5-2±5.17e-2 and VEGF group (n=3) 7.6e-2±5.1e-2. In healthy human volunteers, retinal extraction fraction was measured to be 5.0e-5 ± 6.1e-5 (n=2), whereas this was found to be elevated to 1.2e-3 ± 1.0e-3 in patients for diagnosed DR (n=3). These early results clearly demonstrated a statistically significant elevation in vascular permeability in all diabetic groups compared to controls (p<0.05). The human study was carried out on advanced cases of patients who were known to have DR as a test case; however, the sensitivity of the approaches is demonstrated by the eatly changes in extraction fraction observed at only 48 h after the onset of hyperglycemia in the rat experiments (well before irreversible damage to the retina had occurred). These results are promising for the adaptation of our modified kinetic modeling approach to measure hemodynamics and vascular permeability changes during the early onset of DR when preventative therapies could be most effective.
M.S. in Biomedical Engineering, May 2017
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Title: MECHANICAL AND BIOCHEMICAL FACTORS INFLUENCING INITIAL PLATELET ADHESION TO COLLAGEN: IMPORTANT ROLE FOR SLIDING AND ROLLING IN ACCELERATED AGGREGATE FORMATION
Creator: Au, Bonnie
Date: 2015, 2015-05
Description: Injury at the vessel wall leads to exposure of collagen to which platelets initially adhere, grow into aggregates and eventually thrombotic...
Show moreInjury at the vessel wall leads to exposure of collagen to which platelets initially adhere, grow into aggregates and eventually thrombotic masses which can occlude the vessel lumen. This process underlies the disorders of heart attack and stroke. The initial phase of platelet aggregation governs the extent of thrombus formation. We have investigated initial platelet attachment to collagen-coated surfaces under mechanical and biochemical conditions in a parallel plate flow reactor. A simple algorithm has been developed to simulate the effects of platelet sliding/rolling on the surface with respect to the development of surface aggregate formation. Platelets are hypothesized to stop such movement once they collide with a neighboring platelet in their pathway (due to platelet coherence that strengthens the overall adhesive forces due to platelet-platelet bonding). We and others have observed microscopically that platelets will either attach firmly onto the surface, roll and slide or detach completely from the surface. Platelet behavior was investigated for overall adhesion and the translocation dynamics on overall adhesion on temperature, flow conditions, C-reactive protein (CRP), and coffee consumption. Our findings indicate that temperature, shear force, and CRP promote platelet adhesion and the intake of coffee impedes platelet adhesion.
M.S. in Biomedical Engineering, May 2015
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Title: IDENTIFYING OPTIMAL KINETIC PARAMETERS IN QUANTITATIVE PAIRED-AGENT MOLECULAR IMAGING BY APPLYING COMPUTATIONAL BIOLOGY TECHNIQUES
Creator: Rangnekar, Aakanksha
Date: 2016, 2016-05
Description: Accurate and sensitive discrimination of cancerous tissue from the healthy tissue has been a difficult problem to deal with, resulting in the...
Show moreAccurate and sensitive discrimination of cancerous tissue from the healthy tissue has been a difficult problem to deal with, resulting in the incomplete resection of cancerous tissue and giving rise to ‘call-back’ surgery. Fluorescence guided surgery, which employs a fluorescent imaging agent to highlight key molecular differences between cancerous and healthy tissue is a promising approach for improving cancer discrimination during tumor resection surgery. However, conventional fluorescence guided surgery methods have not been optimized in terms of maximizing the contrast of cancer to healthy tissue and nonspecific sources of contrast in images can potentially obfuscate the reliability of such approaches, typically owing to variable vascular permeability and retention kinetics of fluorescent imaging agents in cancerous tissues. Paired-agent approaches have been proposed to account for these nonspecific factors. The approaches employ co-administration of a control (untargeted) imaging agent with a cancer targeted imaging agents, the measured signal of which is used to “normalize” out nonspecific components of targeted agent distribution so that the highest possible contrast between cancer and healthy tissue can be realized. This thesis explores how tumor contrast can be optimized by a ratiometric application of paired-agent imaging approach depending on pharmacokinetic characteristics of the targeted and control imaging-agents used. Overall, two parameters were found to be of upmost importance: 1) the plasma elimination half-life of the imaging agents should be long or large compared to the tissue efflux rate, k2, ideally > 10 h for typical k2 levels; 2) the efflux rate of the imaging agents from the extracellular space to the intravascular space needs to be relatively high in the range of 0.05-0.13 min-1. This thesis also highlights the importance of the appropriate imaging time while quantifying the cell surface receptors. With the use of simulations and animal models this thesis identifies the use of kinetic parameters playing a role in the paired-agent imaging approach. By making use of the paired-agent imaging approach in the fluorescence guided surgery it would be possible to accurately quantify the cancer cell surface receptors to optimize identification of the cancerous tissue from the healthy tissue.
M.S. in Biomedical Engineering, May 2016
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Title: IMAGING TISSUE SCAFFOLDS WITH X-RAY PHASE CONTRAST IMAGING
Creator: Doe, Frederick
Date: 2014, 2014-12
Description: A major challenge in tissue engineering is imaging within scaffolds. Biomaterials commonly used in tissue engineering have similar x-ray...
Show moreA major challenge in tissue engineering is imaging within scaffolds. Biomaterials commonly used in tissue engineering have similar x-ray absorption properties to native tissue, so they provide poor contrast in radiography. X-ray phase contrast imaging (XPCI) is an imaging modality that measures light/matter interactions other than absorption. By providing insight into these interactions, x-ray phase contrast imaging has the potential to allow imaging of materials used in biomedical applications. In this thesis, a technique for imaging explanted poly(ethylene glycol) (PEG) hydrogels is presented. PEG is a highly biocompatible polymer with widespread use in biomedical applications. Porous PEG hydrogels were synthesized with 100-150 μm pore size through a salt-leaching technique and loaded with fibrin, a natural protein known to stimulate vascularized tissue formation. The hydrogels were formed in the shape of disks and implanted subcutaneously in the backs of rodent animal models for 1, 2 and 3 weeks. The hydrogels and surrounding tissue were harvested at 1, 2, and 3 weeks. After explanation, the hydrogels were placed in formaldehyde and imaged at the National Light Source at Brookhaven National Laboratory using a multiple image radiography (MIR) technique. Five hundred angles were captured of each sample over 180°, and computed tomography was performed. The samples were compared to histological stains to identify specific tissue features that could be identified in the XPCI images. XPCI allowed imaging of hydrogels and identification of interfaces between native tissue and the PEG material. In addition, tissue invasion into the pores of the scaffold could be identified and could be used to quantify the depth of invasion. Muscle tissue could also be seen, and within muscle fibers were visible. With computed tomography, 3D volumes were constructed, enabling analysis throughout the samples.
M.S. in Biomedical Engineering, December 2014
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Title: DESIGN OF A DYNAMIC MUSCULOSKELETAL MODEL OF THE HUMAN HAND FOCUSED ON FUNCTIONAL TASKS
Creator: Barry, Alexander
Date: 2016, 2016-05
Description: This thesis explores the creation and validations of a simulated musculoskeletal model of the human hand with a focus on the aspects of...
Show moreThis thesis explores the creation and validations of a simulated musculoskeletal model of the human hand with a focus on the aspects of pinching. Specifically, the thumb, index finger, and wrist were represented in OpenSim 3.3, using anatomical definitions for increased accuracy. Specifically, the inclusion of physiological axes of rotation at all joints, anatomically accurate passive joint torques, and appropriate moment arms for each muscle. The model was subsequently validated against experimental results found in literature. First, the digit tip force directions produced by each of the 15 muscles were compared to those obtained by loading the corresponding tendons in cadaveric specimens and measuring three-dimensional force generation at the tip of the thumb or index finger. Second, isometric force generation by activation of multiple muscles were compared. Finally, dynamic simulations were run using electromyographic (EMG) recordings as inputs. The capabilities of the model were then explored by using it to predict activation patterns from imposed movement and to simulate extension deficits in a hand affected by stroke. The model generated isometric force in the correct directions for most individual muscles, with the extensor pollicis brevis (EPB) showing the largest directional differences between cadaveric and simulated results. With combined muscle activation patterns the model simulated force profiles accurately, showing only a 5.3% mean squared error (MSE) from the actual force profile. In terms of force magnitudes between the model and simulated results, the model produced significantly lower force magnitudes, especially in the thumb. This validation was also found to be reasonably accurate to the expected motions. With the model anatomically validated, two different simulations were run using the model. First, known kinematics were applied to the model and the muscle activations were simulated; the resultant joint angles were found to match the expected within 10% MSE. Second, a stroke affected hand was simulated, with activation deficits added to each of the muscles individually. It was found through this that, in the model, the intrinsic muscles played a larger role in force production and dynamic motion than the extrinsic muscles. In all, these validations and simulations produce a promising groundwork for the use of this model for further simulation.
M.S. in Biomedical Engineering, May 2016
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