Crayfish Robot Employing Flow Induced by Waving to Locate a Chemical Source

This paper reports on an underwater wheeled robot developed for locating chemical sources under stagnant flow conditions. To draw the chemical staying in the vicinity of the source, the robot generates water currents by waving the arms that mimic maxillipeds of a crayfish. Depending on the patterns for waving of the arms, various flow fields are generated. Determination of the direction of the chemical source is enabled by collecting water samples from different directions. Active flow generation thus serves for extracting desired information from the surrounding chemical concentration field. The development of SPR (surface plasmon resonance) chemical sensors for the crayfish robot is also described. SPR sensors compact enough to mount on the robot are realized by employing gold nanostructures for SPR excitation. Comparison between the SPR sensors and the electrochemical sensors used in the previous paper is made to show the importance of sample collection on the sensor surfaces.