The brain, like many parts of the human body, can experience swelling, also known as cerebral edema. Cerebral edema may occur because of an injury, health related issues, tumors, or even high altitudes[1]. When cerebral edema occurs, a rise in intracranial pressure (ICP) becomes prevalent and may cause a serious threat. Without immediate treatment, increased intracranial pressure can prevent blood from flowing to the brain and depriving it of necessary oxygen it needs to function. A normal ICP is usually between 5-15 mmHg (666 Pa - 1333Pa). Any ICP observed to be above 20 mmHg (2666Pa) can be associated with brain ischemia and is usually treated[2, 3]. If prolonged, high intracranial pressures can be fatal. Current methods of measuring increased ICP are invasive and may involve drilling into the skull. Extreme invasive measures are not always suitable for certain situations. This thesis presents a study of a non-invasive sensor using piezoelectric PVDF wire to measure the ICP. The PVDF wire sensor is wrapped around the outer portion of the human head to measure the integrated hoop strain. Using this hoop strain, the pressure is then calculated from a known coupling factor of strain to pressure outputted from finite element modeling simulations. The coupling factor is then incorporated into a final calibration factor to calibrate the piezoelectric PVDF wire sensor from charge (Picocoulomb) to pressure (Pascal). These calibration factors are proven to be primarily dependent on the circumference of the human skull. Furthermore, part of this study analyzed the effectiveness and validity of the sensor due to asymmetries in the human skull. A comparison of analytical analysis results versus computational results using finite element modeling simulations show that the PVDF wire sensor neglects any asymmetries presented within the test subject. The results of this study show that this sensor will output correct ICP measurements of different subjects using appropriate calibration factors and is a viable option for measuring ICP non-invasively. / Master of Science

The development of composite materials by combining two or more constituents with improved mechanical properties, when compared to either of the constituents alone, has existed since biblical times when straw or horse hair was mixed with clay or mud to produce bricks. During the second half of the twentieth century, modern composites known as fiber reinforced polymers (FRP) - consisting of a reinforcing phase (fibers) embedded into a matrix (polymeric resin or binder) - were developed to meet the performance challenges of space exploration and air travel. With time, externally-bonded FRP applications for strengthening of reinforced concrete (RC) structures gained popularity within the construction industry. To date, the confinement of RC columns using FRP systems is a convenient and well established solution to strengthen, repair and retrofit structural concrete members. This technology has become mainstream due to its cost effectiveness, and relative ease and speed of application with respect to alternative rehabilitation techniques such as steel or concrete jackets. However, significant margins exist to advance externally-bonded composite rehabilitation technologies by addressing economic, technological, and environmental issues posed by the use of organic polymer matrices, some of which are addressed in this dissertation. Articulated in three studies, the dissertation investigates the development of a sustainable, reversible, and compatible fiber reinforced cement-based matrix (FRC) composite system for concrete confinement applications in combination with a novel test method aimed at characterizing composites under hydrostatic pressure. Study 1 develops and characterizes a FRC system from different fiber and inorganic matrix combinations, while evaluating the confinement effectiveness in comparison to a conventional FRP system. The feasibility of making the application reversible was investigated by introducing a bond breaker between the concrete substrate and the composite jacket in a series of confined cylinders. The prototype FRC system produced a substantial increase in strength and deformability with respect to unconfined cylinders. A superior deformability was attained without the use of a bond breaker. The predominant failure mode was loss of compatibility due to fiber-matrix separation, which points to the need of improving fiber impregnation to enable a more efficient use of the constituent materials. Additionally semi-empirical linear and nonlinear models for ultimate compressive strength and deformation in FRC-confined concrete are also investigated. Study 2 compares through a life cycle assessment (LCA) method two retrofitting strategies: a conventional organic-based, with the developed inorganic-based composite system presented in Study 1, applied to concrete cylinders by analyzing three life cycle impact indicators: i) Volatile Organic Compound (VOC) emissions, ii) embodied energy, and, iii) carbon foot print. Overall the cement-based composite provides an environmentally-benign alternative over polymer-based composite strengthening system. Results also provide quantitative information regarding the environmental and health impacts to aid with the decision-making process of design when selecting composite strengthening systems. Study 3 is divided into two parts, Part A presents the development of a novel "Investigation of Circumferential-strain Experimental" (ICE) methodology for characterization of circumferential (hoop) strain of composite laminates, while Part B uses the experimental data reported in Part A to explicitly evaluate the effect of FRP jacket curvature and laminate thickness on strain efficiency. Results showed that the proposed ICE methodology is simple, effective and reliable. Additionally, the ultimate circumferential strain values increased with increasing cylinder diameter, while being consistently lower when compared to similar flat coupon specimens under the same conditions. The ultimate FRP tensile strain was found to be a function of the radius of curvature and laminate thickness, for a given fiber ply density and number. The effect of these findings over current design guidelines for FRP confined concrete was also discussed.