Optical chemical sensors have been the focus of much research attention in recent years because of their importance in industrial, environmental and biomedical applications [1]. This class of sensors combines chemical and biological recognition with advances in optoelectronic technologies. The application of solgel materials to these sensors, especially in the form of thin films, has attracted considerable interest due to the ease of fabrication and design flexibility of the process. The nature of the sol-gel process lends itself very well to the deposition of thin films using a variety of techniques such as dip-coating, spin-coating and spraying. In many sensor applications, the sol-gel film is used to provide a micro-porous support matrix in which analyte-sensitive molecules are entrapped and into which smaller analyte species may diffuse and interact [2,3]. Sol-gel films have many advantages as support matrices over polymer supports, including, for example, strong adhesion, good mechanical strength as well as excellent optical transparency. The versatility of the process facilitates tailoring of the physico-chemical film properties to optimize sensor performance. For example, films can be designed which have optimum porosity while minimizing leaching of the indicator molecules. In this chapter, the versatility of the sol-gel process with regard to the design of films for specific optical chemical sensor applications is highlighted.

Optical chemical sensors.

The guided, single-mode propagation of ultrashort optical pulses is commonly described by a well studied and understood generalized nonlinear Schrodinger equation. Here we present and discuss an extended version for multimode optical fibers and waveguides including polarization effects, high-order dispersion, Kerr and Raman nonlinearities, self-steepening effects, as well as wavelength-dependent mode coupling and nonlinear coefficients. We then investigate the symmetry properties of the nonlinear coupling coefficients for the cases of step-index and circularly symmetric conventional fibers and for microstructured fibers with hexagonal symmetry. Finally, we study the computational complexity of the proposed algorithm.

Description of ultrashort pulse propagation in multimode optical fibers

Remarkable developments can be seen in the field of optical fibre biosensors in the last decade. More sensors for specific analytes have been reported, novel sensing chemistries or transduction principles have been introduced, and applications in various analytical fields have been realised. This review consists of papers mainly reported in the last decade and presents about applications of optical fiber biosensors. Discussions on the trends in optical fiber biosensor applications in real samples are enumerated.

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Recent Development in Optical Fiber Biosensors

In the modern world, a number of therapeutic proteins such as vaccines, antigens, and hormones are being developed utilizing different sophisticated biotechnological techniques like recombinant DNA technology and protein purification. However, the major glitches in the optimal utilization of therapeutic proteins and peptides by the oral route are their extensive hepatic first-pass metabolism, degradation in the gastrointestinal tract (presence of enzymes and pH-dependent factors), large molecular size and poor permeation. These problems can be overcome by adopting techniques such as chemical transformation of protein structures, enzyme inhibitors, mucoadhesive polymers and permeation enhancers. Being invasive, parenteral route is inconvenient for the administration of protein and peptides, several research endeavors have been undertaken to formulate a better delivery system for proteins and peptides with major emphasis on non-invasive routes such as oral, transdermal, vaginal, rectal, pulmonary and intrauterine. This review article emphasizes on the recent advancements made in the delivery of protein and peptides by a non-invasive (peroral) route into the body.

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A review on the strategies for oral delivery of proteins and peptides and their clinical perspectives

https://researchrepository.ucd.ie/bitstream/10197/7800/1/Maher_et_al_2016_ADDR_researchgate.pdf

Intestinal permeation enhancers for oral peptide delivery.

Aims/hypothesis
The development of an orally active insulin formulation will offer great advantages over conventional injectable insulin therapy in the treatment of patients with diabetes mellitus. Since insulin absorption in the intestine is restricted by the natural physiological characteristics of insulin, we developed a small synthetic compound, Nα-deoxycholyl-l-lysyl-methylester (DCK), as an insulin carrier to enhance oral delivery.

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A new drug carrier, Nα-deoxycholyl-l-lysyl-methylester, for enhancing insulin absorption in the intestine

A novel optical fiber fabrication technique was developed by converting the symmetry of the silica substrate into the germanosilicate ring core to efficiently introduce geometric birefringence in an elliptical hollow optical fiber. Due to high ellipticity in the hollow ring core, the fiber provides an extremely high group birefringence of 2.35×10−3 at 1550nm. Single-mode single-polarization guidance was also experimentally confirmed, with a bandwidth of ∼35nm. The generic adiabatic mode conversion capability in the taper also provided a stable fusion splice to conventional single-mode fiber with low loss and high tensile strength.

Versatile control of geometric birefringence in elliptical hollow optical fiber

We have experimentally demonstrated a new compact surrounding refractive-index sensor using MMF-CSF-MMF structure. For refractive index range of 1.30 to 1.42, resolution of 9.68× 10 -3 /nm and linear dynamic range of 20.5dB were obtained at λ=1310nm.

Compact three segmented multimode fiber modal interferometer for high sensitivity refractive-index measurement

We have investigated experimentally and theoretically the birefringence of the elliptic core fiber with irregular air holes. The wavelength dependence of the beat length and the birefringence was measured by the wavelength scanning method. The fiber exhibits ultrahigh birefringence of 1.12×10−2 at 1550 nm. We also calculated the modal birefringence of the fundamental modes in the fiber by using the plane wave expansion method. The calculated birefringence is in excellent agreement with the measured one.

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Soan Kim

Papers

A new drug carrier, Nα-deoxycholyl-l-lysyl-methylester, for enhancing insulin absorption in the intestine

Versatile control of geometric birefringence in elliptical hollow optical fiber

Compact three segmented multimode fiber modal interferometer for high sensitivity refractive-index measurement

Ultrahigh birefringence of elliptic core fibers with irregular air holes

A novel dispersion and PMD tolerant clock phase detector for coherent transmission systems