Investigation of a Capillary-Based Surface Plasmon Resonance Sensor for Biosensing

We report a capillary-based surface plasmon resonance sensor that integrates sample collection, injection, and measurement. The sensor reported here can be fabricated at low cost and possesses a small and robust package. The hollow structure of the capillary not only can be used as a fluid channel but also allows light to travel along a spiral and straight line, which is very helpful for reducing the length of the sensing region. The operation wavelength of the sensor can be tuned with a harmless high-index dielectric layer, which makes it possible to generate a reference signal to correct the effect of changes in the bulk refractive index or temperature. Our experiments show that the sensor can operate at room temperature and is capable of performing label-free detection and real-time monitoring through a single sensing device. Furthermore, similar to needles and insertable probes, the sensor could also potentially be used for minimally invasive medical diagnostics and monitoring. As a biosensor, it will be a practical and specific detection device that can be widely used, such as in biological and life sciences research, and rapid diagnostics.