Browsing by Subject "medical device"

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    Developmentof High Sensitivity Magnetic Biosensors for Biomedical Applications
    (2020-02) Feng, Yinglong
    As a very important subgroup of biosensors, magnetic biosensor is known to possess major advantages over its competitors due to low cost, rapid detection, low background signal in biological tissue and magnetic sensing system has met the requirements to be a portable point-of-care medical system. Providing a useful supplement or alternative for various applications in areas such as diagnosis and cognation study. Detection and quantification of specific biomolecules become increasingly important since the statistical results provide insightful correlation with specific diseases. In the area of disease diagnosis, disease early detection is critical since exposing diseases at early stage will lead to more effective treatments. Biological analytes are low abundance in number or concentration, as a result, many new methods of biosensing are primarily targeting on high sensitivity. One of the promising candidates uses a physical phenomenon called “giant magnetoresistance” (GMR). In GMR element, the electrical resistance changes in response to an applied magnetic field. This technology has been developed and utilized in the hard disk drive industry for decades. Unlike the mature design of GMR biosensor, this dissertation presents a novel GMR magnetic biosensing system with unique particle sensing scheme of localized interaction between particles and sensors. This may provide an alternative path to design GMR sensor with higher sensitivity to truly meet the challenge of detecting low abundance biomolecules in disease early detection. Magnetic sensor can be used in more than assay-based disease detection, it can also be used as a magnetic field sensor to detect magnetic field generated by neuronal electrical activities. Magnetic field generated from neuronal electrical signal is small and it degrades over distance. Great challenge is made for the sensing system to be very sensitive in response to magnetic field, in the same time, to maintain very low overall system noise. We built a Tunnel magnetoresistance (TMR) based magnetic sensing system to address these challenges. TMR stacks and sensor design are optimized to achieve high “zero” field sensitivity, soft magnetic material is sputtered and ion milled to build an integrated magnetic flux concentrator. Sputtering condition and the geometric dimensions of the flux concentrator is also optimized. Low noise analog circuit and different noise reduction methods are utilized to minimize the overall system noise. At last, we have preliminarily demonstrated using our magnetic sensing system to detect brain signals from a rat, Electroencephalography (EEG) sensor is used to verify our magnetic sensor.
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    Essays on Innovation in the Medical Device Industry
    (2021-07) Everhart, Alexander
    This dissertation includes three empirical papers on the development and adoption of medical devices in the United States. Economists attribute as much as half of recent gains in life expectancy in the United States to the use of new medical technologies. When developing medical technologies, manufacturers must consider the “total product lifecycle” of devices, spanning from development costs to regulatory approval to insurer coverage and ultimately patient and physician adoption. The three chapters of this dissertation examine different stages of the total product lifecycle for medical devices.In Chapter 1, I study how medical device firms change their investments in research and develop following external shocks to production costs. Using damage to device manufacturing facilities caused by Puerto Rican hurricanes as a natural experiment, I find that increases in storm exposure cause firms to spend less on research and development and bring fewer medical devices to market. I also find that devices brought to market following storms are cited in competitor regulatory submissions no more or less often than the average medical device. This suggests that device firms do not meaningfully target more or less scientifically innovative projects at the margin when reducing investments in research and development. In Chapter 2, I describe the availability of cost-effectiveness analyses for medical devices in the United States. Cost-effectiveness analyses are not consistently used by insurers when making coverage decisions in the United States. I find that one of the barriers to using cost-effectiveness analyses is the timing of when analyses become available. Cost-effectiveness analyses are not available until several years after regulatory approval. In Chapter 3, I examine the effect of industry payments on physicians’ adoption of Medtronic’s Micra leadless pacemaker in fee-for-service Medicare. Leadless pacemakers have lower complication rates but a higher cost compared to traditional leaded pacemakers. I find that physicians who receive more payments from pacemaker manufacturers are more likely to adopt leadless pacemakers. However, this relationship is not robust to either physician fixed effects or an instrumental variables analysis predicting receipt of manufacturer payments as a function of distance from Medtronic headquarters.