Safe Robotized Polishing of Plastic Optical Fibers for Plasmonic Sensors

Plastic optical fibers (POFs) biosensors are getting widespread in a number of application fields owing to their low cost, high performance, and for their extreme flexibility in terms of detection ability of a large number of specific substances in different matrices. A specific category of such sensors are those based on the surface plasmon resonance (SPR) phenomenon, which can be made very specific by suitable integration with a biological or chemical molecular recognition element (MRE), specifically designed for binding with the desired substance (the analyte). Despite the flexibility of the SPR-POF sensors, their production is still difficult to automate on a large scale because of the special polishing process of the plastic optical fiber. Such a process is currently performed by a human trained operator who rubs the surface of a short fiber segment against a sandpaper sheet by following an 8-shaped path while exerting a specific force in the direction normal to the contact surface. The present paper proposes the adoption of a collaborative robot programmed to perform the same task based on the data acquired from the human operator. To ensure the safe use of the robotic cell by operators who share the same workspace of the robot, the system is endowed with a workspace monitoring system that ensures the polishing task execution while minimizing the possible occurrence of collisions with human operators by suitable exploiting the kinematic redundancy of the robot.