Silica fiber under high pressure increases the risk of fiber breakage or permanent deformation, which may cause sensor failure due to mechanical strength limitations. High pressure can also induce birefringence in optical fiber. In this study, we present a simple design and low-cost high pressure sensor using polymer optical fiber (POF) based on the intensity-variation technique. A side-coupling mechanism in the sensor structure is adopted, which varies the intensity with applied pressure. Two POFs are twisted together to create a sensing region where the light is launched in the first fiber and measurement is taken from the second fiber. In sensing phenomena, cladding mode frustrated total internal reflection occurs when pressure increases. Silicone gel is used in the pressure chamber for sealing and preventing leakage. The sensor structure is able to detect high pressure in the MPa range, where we tested up to 4 MPa. For higher sensitivity, twisted and bend structure is analyzed, and sensitivity is achieved at about 432.21 nW/MPa. However, twisted helical structure is adopted to enhance sensing range which is about 50 cm. The proposed high-pressure sensor structure is easier to fabricate and has high stability because it doesn’t require any destructive method as compared to other conventional methods.

Fast drug-dissolving systems have been introduced to mediate the drugs which are difficult to swallow or having poor water solubility. Rizatriptan benzoate is a drug recommended for the patients of migraine which effect one out of every 5 women and 15 men globally. But least bioavailability (40%–50%) and reduced on set action always increases the demand of a drug carrier in order to overcome these limitations. Here in pullulan mediated fast drug-dissolving systems was developed by using rizatriptan benzoate as a model drug. While rizatriptan loaded pullulan nanofiber mat was prepared via electrospinning. Physiochemical outcomes (SEM, FTIR, and XRD) revealed good compatibility of pullulan nanofibers and rizatriptan thoroughly distributed on electrospun NFs matrix. Wetting time (1 s) and dissolutions time (3 s) suggests burst release of the drug from the polymers matrix as dissolution time is directly proportional with release profile. Further, this was confirmed by UV-release profile studies and maximum release was found within 30 s. In vitro release kinetics were analyzed by fitting the results with higuchi and korsmeyer models.

In this paper, a dual-parameter liquid level and refractive index (R.I.) sensor is fabricated using three pieces of bare polymer optical fibers (POFs), which can independently and simultaneously sense the liquid level and R.I. The proposed sensor design utilizes the twisted coupling technique, in which two optical fibers are twisted and coupled with macro-bending. The liquid level measurement depends on the coupling loss, where the light is transmitted to emission fiber (EF) and twisted with coupled acceptor fiber (AF). The proposed liquid level sensor can measure depths up to 125 mm with a sensitivity of 8.03 nW/mm. Moreover, R.I. sensing depends on the twisted coupled macro-bending (TCMB) technique, where the EF generates bend loss and the AF couples the loss, where the coupled power varies due to the transformation in R.I. of coupling medium. The R.I. sensor revealing a notable sensitivity of -2663%/RIU and an impressive resolution of 3.754 × 10⁻⁴ in the different NaCl-saturated liquids featuring R.I. range extending from 1.333 to 1.361. The experimental findings indicate the sensor exhibits excellent stability and reliability. The sensor’s straightforward, comprehensive, and cost-effective design enables its application in chemical, petroleum, and other industries.

This study introduces a cost-effective solution and sensor arrays for the multipoint liquid-level measuring sensor based on an intensity modulation technique. The sensor structure is based on the twisting of two fibers and creates cascading to achieve a multipoint detection. Three sensors are fabricated on a single illuminated polymer optical fiber. The twisting creates side-coupling between two fibers, and the coupled power is attenuated when liquid emerges in the coupled region. Each sensor has its own output source, which is connected to the power meter. When the liquid-level increases, the coupled power is continuously decreased. The multipoint liquid-level sensor is theoretical and experimentally tested. The experimental results show that sensors have a good response and linearity. The sensors are able to measure the liquid-level up to 12 cm and have a sensitivity of about 0.2726 μW/cm, 0.1715 μW/cm, and 0.1281 μW/cm, respectively. The different flow rate (50 mL/min–300 mL/min) is also analyzed to validate the dynamic response of the sensor. The sensor demonstrates a high sensitivity and resolution in the liquid-level detection. Meanwhile, the liquid-level variation is individually and simultaneously measured. The system does not require any decoupling technique as the system relies on a single LED source, and the coupled power is individually measured from each power meter. The system represents a significant advancement in precise liquid-level sensing technology, as the system has advantages of a flexible, durable, cost-effective, and active response with respect to changes in the liquid-level.

This research introduces an RI sensor for detecting various alcohol species with a designed twisted polymer optical fiber (POF) sensor. The sensor is developed via a straightforward twisting technique to form an effective coupling mechanism. The sensor works on intensity variation where coupled intensity varies when different types of alcohol are added. The structure relies on the twisting of two fibers, where one fiber is used as the illuminating fiber and the other fiber is used as the receiving fiber. Five different types of alcohol are tested (methanol, ethanol, propanol, butanol, and pentanol) as a substant. The experimental results reveal that the sensor is able to detect all five distinct substants effectively by optical power intensity variation. Moreover, the sensor’s sensitivity is analyzed with different factors such as the influence of the bending radius and the coupling length, which reveals that the sensing parameters could be customized depending on specific requirements. The sensor demonstrated consistent responses in repeatability tests, with minimal variation across multiple measurements, highlighting its stability. Additionally, the study explores temperature’s influence, revealing a sensitivity shift for every degree Celsius of change. This POF-based alcohol sensor represents a significant leap forward in optical sensing technology.

This study proposes a non-contact force-measuring sensor design that utilizes a polymer optical fiber. The sensor design uses two separate fibers (i.e. sensor input and sensor output fibers). The sensor input fiber is helically wound around a supportive circular pipe, with aim of creating bend losses at every bend loop. The sensor output fiber gains advantages by coupling the variable optical power from different bend loops of the sensor input fiber. The variable amount of optical power coupling is directly associated with the applied force on the spring, which serves as an intermediary in transferring force to the sensor. Further, for variable ranges of forces, three different springs are used, which sustain variable force ranges (0–20, 0–40 and 0–60 N), respectively. The proposed sensor design addresses the critical need for force sensors capable of effectively measuring force across a wide dynamic range. The results of this study support the sensor design, which has a wide range of force-measuring capabilities, from low to high, with a close and repeatable response. The low-range force measurement (0–20 N) indicates the sensor’s high sensitivity of 0.567 µW N⁻¹. Further, the sensor is also capable of a large force measuring range (0–60 N) with sensitivity of 0.189 µW N⁻¹.