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Implantable intracardiac bioimpedance system
textAn implantable intracardiac bioimpedance system has been designed to measure the real and imaginary parts of impedance in a dynamic cardiac setting. The system is broken into two parts: an implantable wireless device and a desktop base station. This measurement is performed using both tetrapolar and tripolar electrode configurations where a 20 kHz current field is applied to the intracardiac blood pool and myocardium. Epochs of discrete voltage samples from the resulting electric field are analyzed using a digital signal processing algorithm to generate impedance measurements. Measurements are then wirelessly transmitted from the implantable device to a base station where advanced signal processing algorithms are applied and the data is plotted in real-time. The final system measures 485 impedance samples/sec, consumes 50 mA when active, and has a percent of measurement error less than 1% for the intracardiac bioimpedance range. The device has been extensively tested to ensure the quality of measurements required for future human use. Instrument design, calibration, verification, experimentation, and modeling are the primary topics of this thesis. Moving forward, the system will be used in studies where dynamic bioimpedance signals measured in the right and left ventricles of the heart will be used to derive stroke volume.Electrical and Computer Engineerin
Security and privacy issues in implantable medical devices: A comprehensive survey
Bioengineering is a field in expansion. New technologies are appearing to provide a more efficient treatment of diseases or human deficiencies. Implantable Medical Devices (IMDs) constitute one example, these being devices with more computing, decision making and communication capabilities. Several research works in the computer security field have identified serious security and privacy risks in IMDs that could compromise the implant and even the health of the patient who carries it. This article surveys the main security goals for the next generation of IMDs and analyzes the most relevant protection mechanisms proposed so far. On the one hand, the security proposals must have into consideration the inherent constraints of these small and implanted devices: energy, storage and computing power. On the other hand, proposed solutions must achieve an adequate balance between the safety of the patient and the security level offered, with the battery lifetime being another critical parameter in the design phase
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