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Hydrocephalus is a chronic medical condition characterized by the excessive accumulation of cerebrospinal fluid in the brain. It is estimated that 1-2 of every 1000 babies in the United States is born with congenital hydrocephalus, with many individuals acquiring hydrocephalus later in life through brain injury. Despite these alarming statistics, current shunts for the treatment of hydrocephalus display operational failure rates as high as 40-50% within two years following implantation. Failure of current shunts is attributed to complexity of design, external implantation, and the requirement of multiple catheters. The presented hydrogel wafer check valve avoids all the debilitating features of current shunts, relying only on the swelling of hydrogel for operation, and is designed to directly replace failed arachnoid granulations- the brain’s natural cerebrospinal fluid drainage valves. The valve was validated via bench-top (1) hydrodynamic pressure-flow response characterizations, (2) transient response analysis, and (3) overtime performance response in brain-analogous conditions. In-vitro measurements display operation in range of natural CSF draining (cracking pressure, PT ~ 1–110 mmH2O and outflow hydraulic resistance, Rh ~ 24 – 152 mmH2O/mL/min), negligible reverse flow leakages (flow, QO > -10 µL/min), and demonstrate the valve’s operational reproducibility of this new valve as an implantable treatment.
ContributorsAmjad, Usamma Muhammad (Author) / Chae, Junseok (Thesis director) / Appel, Jennie (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
This paper introduces a wireless reconfigurable “button-type” pressure sensor system, via machine learning, for gait analysis application. The pressure sensor system consists of an array of independent button-type pressure sensing units interfaced with a remote computer. The pressure sensing unit contains pressure-sensitive resistors, readout electronics, and a wireless Bluetooth module, which are assembled within footprint of 40 × 25 × 6mm3. The small-footprint, low-profile sensors are populated onto a shoe insole, like buttons, to collect temporal pressure data. The pressure sensing unit measures pressures up to 2,000 kPa while maintaining an error under 10%. The reconfigurable pressure sensor array reduces the total power consumption of the system by 50%, allowing extended period of operation, up to 82.5 hrs. A robust machine learning program identifies the optimal pressure sensing units in any given configuration at an accuracy of up to 98%.
ContributorsBooth, Jayden Charles (Author) / Chae, Junseok (Thesis director) / Chen, Ang (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
Microwave tomography (MWT) differs from the current forms of biomedical imaging modalities by measuring the dielectric properties in different tissues in order to create an image of the object under evaluation. This technology could be harnessed for the evaluation of a stroke because the areas of the brain that are not being provided oxygen will have a reduced concentration of blood, leading to a reduced relative permittivity (also referred to as dielectric constant). Strokes themselves require accurate diagnosis for proper treatment to be administered. Microwave tomography offers advantages of stroke diagnosis over imaging methods such as magnetic resonance imaging (MRI) and computerized tomography (CT). Like MRIs, microwave tomography passes only non-ionizing radiation through the patient, allowing for multiple safe scans. Because MWT requires only an array of antennas sending a non-ionizing electromagnetic field, which is on the level of the fields sent in cell phones, a patient undergoing a stroke could be diagnosed inside an ambulance with multiple MWT scans, greatly reducing the time before treatment. The challenge for this thesis is to correctly solve an ill-posed problem presented in a microwave tomography system and output an image of the object's electrical properties. The system itself is an inverse problem because the object to be imaged and its properties are unknown. Rather, the incident field and resulting scattered field due to interaction with the object of interest are known. To achieve a unique solution for this problem, a software implementation of a common microwave inversion method known as Born's Iterative Method is realized through MATLAB.
ContributorsNam, Suhyun (Author) / Chae, Junseok (Thesis director) / Liu, Shiyi (Committee member) / W. P. Carey School of Business (Contributor) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The team has designed and built a golf swing analyzer that informs the user of his mistakes while putting with a golf club. The team also interfaced a Linux program with the analyzer that allows the user to review the flaws in his golf swing. In addition, the application is more personalized than existing devices and tailored to the individual based on his level of experience. The analyzer consists of an accelerometer, gyroscope, magnetometer, vibration motor, and microcontroller that are connected on a board that attaches to the top of the shaft of a golf club, fitting inside a 3D printed case. The team has assembled all of the necessary hardware, and is able to successfully display critical parameters of a golf putt, as well as send instant feedback to the user. The final budget for this project was $378.24
ContributorsKaur, Hansneet (Co-author) / Cox, Jeremy (Co-author) / Farnsworth, Chad (Co-author) / Zorob, Nabil (Co-author) / Chae, Junseok (Thesis director) / Aberle, James (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
Hydrocephalus is a chronic neurological condition affecting an estimated 1 in every 500 infants born. The most common treatment method involves surgical implantation of a shunt system; however these systems have a high failure rate resulting in repeat invasive surgeries. A promising approach being researched to treat hydrocephalus is a miniaturized valve composed of silicon and a hydrogel material. The current chemical cross-linker used in the hydrogel, EGDMA, however is susceptible to hydrolytic cleavage due to the ester groups.
This thesis proposed a novel hydrogel composed of a HEMA backbone and methacrylated Jeffamines as the chemical cross-linker as a possible replacement for the HEMA and EGDMA hydrogel used currently in the hydrocephalus valve. Jeffamine EDR-148 was methacrylated through reaction with methacryloyl chloride and characterized using 1H NMR spectroscopy. Subsequently, hydrogels were synthesized, using both EGDMA and EDR-MA, and the properties were compared through swelling and rotational rheology. Finally, degradation tests were performed to compare the hydrolytic stability of the two cross-linkers.
Results of this work demonstrated that Jeffamine EDR-148 was able to be successfully methacrylated and used to synthesize a hydrogel. The new hydrogel was shown to have comparable mechanical behavior and robustness to the EGDMA hydrogel, with slightly increased swelling capabilities. Degradation tests did not confirm the theory that the EDR-MA gels would exhibit greater hydrolytic stability however. Future work includes perfecting the purification of the EDR-MA, conducting a longer-term degradation study at physiologically relevant conditions, and demonstrating the tunability of the Jeffamine hydrogels.
This thesis proposed a novel hydrogel composed of a HEMA backbone and methacrylated Jeffamines as the chemical cross-linker as a possible replacement for the HEMA and EGDMA hydrogel used currently in the hydrocephalus valve. Jeffamine EDR-148 was methacrylated through reaction with methacryloyl chloride and characterized using 1H NMR spectroscopy. Subsequently, hydrogels were synthesized, using both EGDMA and EDR-MA, and the properties were compared through swelling and rotational rheology. Finally, degradation tests were performed to compare the hydrolytic stability of the two cross-linkers.
Results of this work demonstrated that Jeffamine EDR-148 was able to be successfully methacrylated and used to synthesize a hydrogel. The new hydrogel was shown to have comparable mechanical behavior and robustness to the EGDMA hydrogel, with slightly increased swelling capabilities. Degradation tests did not confirm the theory that the EDR-MA gels would exhibit greater hydrolytic stability however. Future work includes perfecting the purification of the EDR-MA, conducting a longer-term degradation study at physiologically relevant conditions, and demonstrating the tunability of the Jeffamine hydrogels.
ContributorsTrimble, Kari Leigh (Author) / Green, Matthew (Thesis director) / Chae, Junseok (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05