In the UK, it is now recognised that 1 in 2 people born after 1960 will develop some form of cancer during their lifetime. Diagnosing patients whilst in the early stages drastically improves their chances of survival but up until now the gold standard for cancer detection is via a lengthy excision biopsy procedure, which relies on the skill of a histopathologist. Evidently, the need for a faster solution is paramount. The mid-infrared (MIR) spectral region covers the wavelengths 3-25 μm and characteristic vibrational spectra unique to each molecular type. Subtle changes in the specific spectral response within this region are indicative of changes within the cells relative to normal cells, signifying the presence or absence of a disease. Our goal is to carry out disease diagnosis in vivo. Reaching these wavelengths has previously presented difficulties as conventional MIR blackbody light sources are weak and optical fibers for transmitting MIR light to/from tissue in vivo can be limited by strong material absorption such as silica glass >2.4 μm and tellurite, and heavy metal fluoride, >4.75 μm. However, chalcogenide glasses have been shown to transmit MIR light out to 25 μm. This paper reports on a glass composition in the Ge-Sb-Se system and its suitability as an optical fiber for the transmission of MIR to and from tissue samples, enabling in vivo mapping for an immediate diagnostic response- a technique termed ‘optical biopsy’.
In the 21st century, cancer has become a common and feared illness. Early detection is crucial for delivering the most
effective treatment of patients, yet current diagnostic tests depend upon the skill of a consultant clinician and histologist
for recognition of the cancerous cells. Therefore it is necessary to develop a medical diagnostic system which can
analyze and image tissue instantly, removing the margin of human error and with the additional benefit of being
minimally invasive. The molecular fingerprint of biological tissue lies within the mid-infrared (IR) region of the
electromagnetic spectrum, 3-25μm wavelength. This can be used to determine a tissue spectral map and provide
information about the absence or existence of disease, potentially in real-time and in vivo. However, current mid-IR
broadband sources are not bright enough to achieve this. One alternative is to develop broadband, mid-IR,
supercontinuum generation (SCG). Chalcogenide glass optical fibers have the potential to provide such mid-IR SC light.
A popular chalcogenide glass fiber type is based on Ge-As-Se. For biomedical applications it is prudent to avoid the use
of arsenic, on account of its toxicity. This paper investigates replacing arsenic with antimony, towards Ge-Sb-Se smallcore
optical fibers for SCG. Physical properties of candidate glass pairs are investigated for glass stability via differential
thermal analysis etc. and fiber optical loss measurements of associated fibers are assessed. These results are compared to
analogous arsenic-containing chalcogenide glasses and optical fibers, and conclusions are drawn focusing on whether
there is potential for antimony chalcogenide glass to be used for SCG for mid-infrared medical diagnostics.