"In recent years, technological advances have allowed the development of sensors for industry, medicine, or research applications. One of these novel technologies that has had a profound impact on the sensor community is optical since they offer significant advantages such as flexibility, compact size, lightweight and immunity to electromagnetic interference. In this work, optical fiber Fabry-Perot interferometers are studied and used to develop in-line, compact and simple to fabricate sensors for real-time applications. Novel schemes are proposed and experimentally demonstrated to measure strain, room-temperature, relative humidity, and refractive index with improved performance."