Numerous Applications of Fiber Optic Evanescent Wave Fourier Transform Infrared (FEW–FTIR) Spectroscopy for Surface and Subsurface Structural Analysis

Abstract

A new infrared (IR) interferometric method has been developed in conjunction with low-loss, flexible optical fibers, sensors, and probes. This combination of fiber optical sensors and Fourier Transform (FT) spectrometers can be applied to many fields, including: (i) noninvasive medical diagnostics of cancer and other different diseases in vivo; (ii) minimally invasive bulk diagnostics of tissue; (iii) remote monitoring of tissue, chemical processes, and environment; (iv) surface analysis of polymers and other materials; (v) characterization of the quality of food, pharmacological products, cosmetics, paper, and other wood-related products, as well as (vi) agricultural, forensic, geological, mining, and archeological field measurements. In particular, our nondestructive, fast, compact, portable, remote, and highly sensitive diagnostics tools are very promising for subsurface analysis at the molecular level without sample preparation. For example, this technique is ideal for different types of soft porous foams, rough polymers, and rock surfaces. Such surfaces, as well as living tissue, are difficult to investigate by traditional FTIR methods. We present here FEW–FTIR spectra of polymers, banana and grapefruit peels, and living tissues detected directly at surfaces. In addition, results on the vibrational spectral analysis of normal and pathological skin tissue in the wavenumber region 850–4000cm−1 are discussed.