In-vivo biomedical monitoring by fiber optic systems

The development of fiber optic sensors for medical applications originated nearly twenty years ago 12 and has been expanding ever since. The success of these sensors is a result of the simplicity of the sensorphysician interface and their notable degree of reliability and biocompatibility. Fiber optic sensors fully satisfy the requisite of biocompatibility, i.e., they do not adversely affect the body nor are they adversely affected by it . The latter consideration should not be taken lightly, in fact often one thinks only about the dangerous effect that an invasive sensor can cause to the human body and does not consider that, especially in chemical sensors where an opirode is fixed at the end of the fibers, the local environment can notably impair sensor performance. The current fiber optic sensors are mostly based on silica and plastic fibers and coupled to sensitive fiber sections or optrodes, and make use of intensity modulation interrogation schemes. An emerging group of sensors is that based on M1D-1R fibers, which are now providing excellent quality in terms of nontoxicity, flexibility, and handling. Table I summarizes the main application fields and working principles of the sensors described in this overview.