Abstract:
This paper presents a finite element method used to simulate and analyze strain transfer from bone to a strain gauge coated with a calcium phosphate ceramic (CPC). The model was built using gross morphometric and histological measurements from prior experimental studies and was validated using analytical solutions and direct comparisons to experimental data from a separate study. The interface between the bone and the strain gauge's sensing surface consisted of polysulfone, a polysulfone/CPC layer, and a CPC/bone layer. Through a series of parameter studies, the authors investigated the effects of various factors on strain transfer, including interface thickness and modulus, gauge geometry, partial gauge debonding, and waterproofing. The findings indicated that both interface thickness and modulus significantly affect strain transfer, with an optimal strain transfer occurring at an interface modulus of approximately 2 GPa. Strain transfer was found to consistently decrease as the interface thickness increased. While debonding along the lateral edges had a minimal effect, debonding at the proximal and distal ends of the sensing element led to a decrease in strain transfer. Additionally, a waterproofing layer reduced strain transfer, with a more pronounced effect as the layer's modulus or thickness increased. Based on these simulations, the study provides specific recommendations to optimize strain transfer for experimental studies using CPC-coated gauges.
