Advances in Optical Analysis of Materials and Complex Biological Systems Using Infrared Spectroscopy

Abstract

Infrared spectroscopy (IRS) is an increasingly important optical technique because the properties of light in this part of the electromagnetic spectrum enable interactions with materials and complex biological systems that provide unique information that has both research and commercial applications. This review summarizes the basic optical principles employed in IRS systems and outlines recent technological advances that have improved the functionality and applicability of IRS instruments. The relevance of the principal practical applications of near-infrared spectroscopy (NIRS), mid-infrared spectroscopy (MIRS), and hyperspectral imaging (HI) in materials science, agriculture, and medicine is highlighted, and key progress made with the software used for the analysis of raw optical data is described. The shorter wavelengths in the near-infrared (NIR) range of the spectrum achieve greater penetration than those in the mid-NIR range. NIRS is now a prominent analytical technology, and its growing role in medicine is the principal focus of this review. MIRS is an important and widely used sample characterization and analytical technique. NIR HI enables the chemical constituents in a sample to be analyzed by capturing complete spectral data at each sample point; the unique spectral signatures generated then allow different chemicals to be visualized and identified. Received: 16 December 2025 | Revised: 4 March 2026 | Accepted: 23 March 2026 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Andrew J. Macnab: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Project administration.