We demonstrate a fiber optic surface plasmon resonance (SPR) biosensor based on smart phone platforms. The light-weight optical components and sensing element are connected by optical fibers on a phone case. This SPR adaptor can be conveniently installed or removed from smart phones. The measurement, control and reference channels are illuminated by the light entering the lead-in fibers from the phone’s LED flash, while the light from the end faces of the lead-out fibers is detected by the phone’s camera. The SPR-sensing element is fabricated by a light-guiding silica capillary that is stripped off its cladding and coated with 50-nm gold film. Utilizing a smart application to extract the light intensity information from the camera images, the light intensities of each channel are recorded every 0.5 s with refractive index (RI) changes. The performance of the smart phone-based SPR platform for accurate and repeatable measurements was evaluated by detecting different concentrations of antibody binding to a functionalized sensing element and the experiment results were validated through contrast experiments with a commercial SPR instrument. This cost-effective and portable SPR biosensor based on smart phones has many applications, such as medicine, health and environmental monitoring.

Fiber-optic (FO) surface plasmon resonance (SPR) sensors can be used as label-free and highly sensitive tools for biosensing. They have been widely applied in fields of environmental monitoring, food safety, and clinical diagnosis. In this article, the development and advancement of FO-SPR sensor were reviewed. And the principle and performance of multiple SPR techniques based on optical fiber for sensing purposes were briefly summarized. Different prototypes of FO-SPR biosensors were meticulously outlined, followed by detailed discussion on novel structures and techniques. Finally, we presented an overview of most representative progresses in biochemical sensing applications using FO-SPR sensors and their future development.

We report a new approach to analyze both vapor and liquid phases by utilizing a tapered fiber optic surface plasmon resonance (SPR) probe. This technique employs a fiber optic SPR probe with a modified geometry to tune the SPR coupling wavelength–angle pair. The observed composite spectrum included two distinct SPR dips associated with surface plasmons excited in the gas and liquid active regions. This sensor is able to detect refractive index changes in both vapor and liquid phases individually by simultaneous monitoring SPR coupling wavelengths from the two sensing surfaces.