Wireless Biodegradable Resonant circuit for Strain Sensor in Hip Implant applications

Abstract

Hip replacement surgery, also termed total hip arthroplasty, is a surgical intervention intended to substitute a deteriorated or dysfunctional hip joint with an artificial prosthesis. This procedure is commonly indicated for individuals experiencing severe hip discomfort resulting from conditions like osteoarthritis, rheumatoid arthritis, hip fractures, or other hip-related issues that significantly impair mobility.

Globally, more than 1 million total hip replacement surgeries are conducted annually. Given the substantial mechanical loads experienced by hip implants during regular activities, a thorough understanding and early identification of potential issues before implant failure are imperative. Continuous monitoring of strain is crucial to assess how the implant responds to various stresses over time. This monitoring aids in evaluating the implant’s durability and performance under diverse stress conditions, enabling proactive interventions, if necessary, to prevent critical failures.

Strain monitoring acts as a diagnostic tool to assess the implant’s status and the surrounding tissues. Deviations in strain patterns may signify problems such as implant loosening, wear, or bone loss around the implant. Moreover, this monitoring technique helps customize rehabilitation programs and recommend specific activities based on individual strain levels. Consequently, this tailored approach enhances recovery outcomes while mitigating associated risks.

This project involves the development of a passive wireless resonant circuit that will be used in the future in a sensor designed to detect strain on hip implants for early failure detection. The strain is anticipated to cause fluctuations in the frequency. To evaluate the LC (inductor-capacitor) resonator design at a specific frequency, a simulation model was established using the Computer Simulation Technology (CST) Microwave Studio as the simulation platform. The fabrication of this LC resonant circuit employs cleanroom techniques and protocols to ensure precision and reliability in its structure. Subsequent to fabrication, the resonator underwent characterization employing an antenna to ascertain resonance frequency alterations in accordance with theoretical expectations. The results indicated a detectable shift in resonant frequency corresponding to designs representing different strains.