Sharif Digital Repository

In this thesis a novel passive method for integrated blood pressure monitoring in implantable applications has been proposed. The main constraints of such implantable systems are power consumption, area and simplicity of the implanted part and detected pressure is transmitted wirelessly to the external system and recorded. In this thesis an oscillator in 0.18um CMOS process has been proposed to detect the resonance frequency of the implanted tank circuit in the external unit of an implantable blood pressure monitoring system. Other designed circuits include a buffer, frequency detector, voltage to current converter and an 8 bit analog to digital converter. The system is capable of measuring... 

Titanium alloy Ti-6Al-4V ELI with high biocompatibility and corrosion resistance, has a lot of applications in biomedical engineering. Disadvantage of this alloy is it’s disability to create a fast and good contact with the host/bone environment, after implanting in the body. Beside that it has low wear resistance. Nowadays to optimize the wear resistance, bioactivity and osteoconduction of surface of implants which are made from this alloy, the surface morphology are optimized in size and distribution. Different surface treatments are used for producing rough and porous surfaces to improve bioactivity along with wear resistance. In this study, surface modification of Ti-6Al-4V ELI was done... 

In this thesis, concerning Eigenstrain Theory, the micromechanical formulation of dental implants has been derived for the first time in the fields of Mechanics and Medical Science. The proliferation of using dental implants as a prosthesis for the people who lost their teeth because of poor maintenance and smoking cigarette results in scientists think more about the design of these implants and their stress fields inside the mandible. It is crystal clear that these stress fields cause stress shielding, which is a phenomenon that brings about bone loss or decrement in the bone density. Hence, if we know the stress that is produced by the implants inside the mandible, we can optimize the... 

This study was performed to synthesize Ag-doped TiO2 nanotubes and investigate the antibacterial property of the nanostructure. In the first step, self-organized TiO2 nanotubes were fabricated through anodizing in an electrolyte containing 0٫3 Wt% NH4F, 0٫2٪V DI water and ethylene glycol. Anodizing was performed in 30 and 60V for 2hrs in order to have different nanotube diameters. In the second step, photoreduction process was done on the way to dope Ag nanoparticles on the nanotubes. Herein, AgNO3 solution concentration, time period of TiO2 nanotubes soaking in the solution, time period of UV irradiation and ethanol solution concentration were taken as factors to achieve Ag nanoparticles in... 

Loosening and gap opening at the bone-implant interface depends on several physiological and mechanical factors such as bone remodeling, stress concentration, and variation in load transfer pathway. Since fracture of orthopedic material at the interface is one of the major failure mode of total joint implants, this study focused on the micromechanical behavior of the interface. Using a two-dimensional FE model, with pure compressive, tensile, and shearing forces applied on bone or cement, ratio of the stress at the interface to the applied stress has been calculated. Stress distribution was considered as a function of porosity,angle of bead contact to surface, as well as size of bead for two...