Near-infrared spectroscopy (NIRS) is a rapidly developing and promising technology with potential for spectrographic analysis. Understanding NIRS measurements on the implant-tissue interface for hydrogen gas formation as part of degradation is essential for interpreting the biodegradable Magnesium (Mg) based implants. This paper introduces novel NIR optical probe that can assess the state of Mg implant's degradation when in contact with biological tissues. A tissuemimicking phantom (TMP) to mimic biological tissue's optical properties helps investigate changes in reflectance spectra due to bubble formation at the implant-tissue interface. Spectra taken from different TMP samples containing biodegradable Mg and non-degradable Titanium (Ti) disk are suitable for evaluating the implant's interaction. The results show that the reflection in TMP for samples containing Mg disks, confirms the presence of hydrogen bubbles at the surface of implants. Multi-distance optical probe with depth selectivity of 3mm and 4mm has shown to be an effective tool to monitor bubble effect on different samples.

Biodegradable magnesium-based implants offer mechanical properties similar to natural bone, making them advantageous over nonbiodegradable metallic implants. However, monitoring the interaction between magnesium and tissue over time without interference is difficult. A noninvasive method, optical near-infrared spectroscopy, can be used to monitor tissue’s functional and structural properties. In this paper, we collected optical data from an in vitro cell culture medium and in vivo studies using a specialized optical probe. Spectroscopic data were acquired over two weeks to study the combined effect of biodegradable Mg-based implant disks on the cell culture medium in vivo. Principal component analysis (PCA) was used for data analysis. In the in vivo study, we evaluated the feasibility of using the near-infrared (NIR) spectra to understand physiological events in response to magnesium alloy implantation at specific time points (Day 0, 3, 7, and 14) after surgery. Our results show that the optical probe can detect variations in vivo from biological tissues of rats with biodegradable magnesium alloy “WE43” implants, and the analysis identified a trend in the optical data over two weeks. The primary challenge of in vivo data analysis is the complexity of the implant interaction near the interface with the biological medium.

The objectives of reliability design evaluation are discussed. The application of fault tree analysis as a design-evaluation technique is described with reference to a communications receiver system. A criticality analysis is performed on the system, and, arising from this, it is shown that more usual methods of evaluating system reliability are inadequate to describe the reliability of systems which can suffer different forms of performance degradation. A reliability figure of merit is derived which takes account of the severity of various forms of performance degradation, and this is used to compare the reliability of alternative design configurations.