Fiber optic sensors have become a mainstream sensing technology within a large array of applications due to their inherent benefits. They are now used significantly in structural health monitoring, and are an essential solution for monitoring harsh environments. Since their first development over thirty years ago, they have also found promise in security applications. This paper reviews all of the optical fiber based techniques used in physical intrusion detection systems. It details the different approaches used for sensing, interrogation and networking, by research groups, attempting to secure both commercial and residential premises from physical security breaches. The advantages and disadvantages of the systems are discussed and each of the different perimeter protection methods are outlined, namely, in-ground, perimeter fence, and window and door protection. The study reviews the progress in optical fiber based intrusion detection techniques from the past through to current state-of-the-art systems and identifies areas which may provide opportunities for improvement, as well as proposing future directions in this field.

Interpretation of bowel sounds (BS) provides a convenient and non-invasive technique to aid in the diagnosis of gastrointestinal (GI) conditions. However, the approach’s potential is limited by variation between BS and their irregular occurrence. A short, manual auscultation is sufficient to aid in diagnosis of only a few conditions. A longer recording has the potential to unlock additional understanding of GI physiology and clinical utility. In this paper, a low-cost and straightforward piezoelectric acoustic sensing device was designed and used for long BS recordings. The migrating motor complex (MMC) cycle was detected using this device and the sound index as the biomarker for MMC phases. This cycle of recurring motility is typically measured using expensive and invasive equipment. We also used our recordings to develop an improved categorization system for BS. Five different types of BS were extracted: the single burst, multiple bursts, continuous random sound, harmonic sound, and their combination. Their acoustic characteristics and distribution are described. The quantities of different BS during two-hour recordings varied considerably from person to person, while the proportions of different types were consistent. The sensing devices provide a useful tool for MMC detection and study of GI physiology and function.

This paper reviews fiber Bragg grating sensing technology with respect to its use in mainstream industrial process applications. A review of the various types of sensors that have been developed for industries such as power generation, water treatment and services, mining, and the oil and gas sector has been performed. A market overview is reported as well as a discussion of some of the factors limiting their penetration into these markets. Furthermore, the author's make recommendations for future work that would potentially provide significant opportunity for the advancement of fiber Bragg grating sensor networks in these mainstream industries.

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