in vivo monitoring of biological processes [79], and biomedical sensing such as
noninvasive glucose measurements [80] and cancer diagnosis [81].
23.5.3 Chemical Sensing
23.5.3.1 Chemical Analy sis and Monitoring
All organic species exhibit vibrational modes within the 2- to 16-mm wave-
length region. This makes FEWS an excellent tool for remote detection of a wide
variety of chemicals and biochemicals ranging from proteins and enzymes to
simple molecules such as ethanol and benzene.
Chemical detection of butanone [82] by means of FEWS was reported during
the late 1980s. Chemical analyses were then performed on acetone, ethanol, and
sulfuric acid using chalcogenide fibers [83, 84]. It was shown that the detection
versus concentration curve follows a