An In-Fiber Michelson Interferometer Long-Period Grating (LPG) With Integrated Sol-Gel and Aptamer Coatings for Biosensor Development

Abstract

<p>In this work, an in-fiber Michelson interferometer Long-Period Grating (LPG) biosensor with integrated sol-gel and aptamer coatingd was used for the development of a biosensor for adenosine triphosphate. A macroporous gold-nanoparticle doped sol-gel derived silica film was coated on the sensing head to enhance surface area and the sensitivity of the LPG based biosensor and to act as a surface for subsequent aptamer immobilization. The large surface area of the sol-gel film increases the number of immobilized aptamers, while the presence of the gold nanoparticles improves the refractive index match with the fiber cladding, enhancing sensitivity. The thin film, which is only two hundred nanometers thick, ensures the evanescent wave penetrates into the ambient environment. The LPG sensor has been demonstrated to work for the selective sensing of ATP in solution. The origin of the sensitivity enhancement is confirmed via simulation and experiments which included the design and fabrication of the LPG sensor.</p>