Modeling, Simulation and Validation of a Bio-Inspired and Self-Powered Miniature Pressure Sensing System for Monitoring Cerebral Intra Aneurysmal Pressure
AuthorMohan, Nithya P.
Electrical and Biomedical Engineering
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Intracranial aneurysm rupture is one of the main cause for the intracranial bleeding. A brain aneurysm is an abnormal focal bulging of the arteries in the brain. As an aneurysm grows, its wall becomes thinner and weaker, which is more prone to rupture. Rupture of the intracranial aneurysm leads to releasing blood into the spaces around the brain - called a subarachnoid hemorrhage (SAH). 10 to 15% of the patients with subarachnoid hemorrhage die immediately. To prevent aneurysmal bleeding, it is essential to seclude the aneurysm from the blood circulation. This can be done with open craniotomy with microsurgical clipping and minimally invasive endovascular surgery. One of endovascular surgical technique is to place stent/flow-diverter across the neck of the aneurysm. The stent across the aneurysm reduces the flow within the aneurysm and help to form the thrombus within the aneurysm. However, approximately 3% people with the flow- diverter treatment may have delayed aneurysm bleeding after the stent placement. Short-term studies show that the stents can reduce the flow within the aneurysm but not the pressure. Currently there is no other device available to measure the intracranial intraaneurysmal pressure. This work is on designing a bio-inspired, self-powered, passively operated PVDF pressure sensor that can be deployed within the aneurysm, during flow diverting endovascular treatment that is very sensitive to small changes in pressure. The design utilizes the ear mechanics benefits by consisting of the circular vibrating membrane which vibrates based on the intraaneursymal pressure changes. This mimic the tympanic membrane part of the ear. The design continues to follow the middle ear’s mechanical advantage mechanism by incorporating the surface area increase and leverage mechanism, by the other side of the vibrating membrane been connected to three pole-links structures similar to the three bones of the middle ear to perform the middle ear’s amplification mechanism. This is followed by a composite cantilever beam structure with the sensor strips, which mimics the coiled cochlea of the inner ear in elongated form. This piezoelectric sensor strips are responsible for the passive mechanoelectrical conversion and generation of electric voltage, for the intraaneursymal pressure change application. Simulation, experiments and analysis at every level are done. Simulation and experimental result correlate and match the modeling.