WIRELESS IMPLANTABLE MAGNETOELASTIC SENSORS AND ACTUATORS FOR BIOMEDICAL APPLICATIONS

Magnetoelastic sensors represent a low-cost wireless and battery-less method for monitoring parameters in embedded or implanted applications; however, some limitations still exist preventing their commercial implementation. Presented in this work are a variety of studies that are aimed at improving the feasibility of magnetoelastic materials for sensing and actuating applications. Magnetoelastic resonant sensors of non-standard geometries were investigated to determine if geometry could play a role on the sensitivity of the sensor response to mass loading. It was shown that a significant increase in sensitivity could be achieved by using triangular sensors rather than standard rectangular strips. A method for monitoring multiple parameters on a single magnetoelastic resonant strip was also pursued. It was demonstrated that multiple parameters will have different effects depending on the location of the applied load due to the effect of sensor areas with zero vibration at different harmonics of the fundamental resonant frequency. Magneto-harmonic sensors and actuators were also explored in this work. Specifically, it was demonstrated that magnetoelastic sensors could be implemented as a means of detecting stresses on deep tissue wounds, which are critical for proper healing of certain wound sites after surgery. Both a suture and a suture anchor design were investigated for their efficacy at monitoring forces applied to tendon repair sites. Two detection devices were fabricated and built for this work which represent low-cost alternatives (both less than $200 each) to commercially available alternatives that minimally cost tens of thousands of dollars. This advancement reinforces the claim that magnetoelastic materials are a low-cost and portable sensing solution. The biodegradability and cytotoxicity of a promising magnetoelastic material for biomedical applications, specifically Galfenol (iron-gallium), was also investigated. Cytotoxicity tests demonstrated that concentrations much higher than would be likely to be encountered in vivo are necessary to cause significant cellular toxicity. Additionally, surface characterization of the degraded materials suggests that the degradation rate of Galfenol can be wirelessly controlled through application of externally applie