Design and fabrication process for artificial lateral line sensors

Biological sensory systems often display great performance, inspiring engineers to develop artificial counterparts. The lateral line system of fish has been widely studied by biologists for its crucial role in fish behaviour. Moreover, recently the robustness, sensitivity and consequently wide range of applications that potentially benefit from the abilities of such a system have attracted the attention of engineering community. Aquatic flow sensors based on the lateral line of fish are useful in underwater robotic applications for hydrodynamic imaging of complex and noisy environments to provide informnation for, for example, surveillance, navigation and obstacle detection. The speculative ability to manoeuvre in murky or dark water, especially object detection at short range, has strongly driven research in this area. This chapter begins with a brief review of the state of the art flow sensors inspired by neuromasts. Subsequently, the design principles and fabrication scheme for a differential capacitive flow sensor incorporating a hair-like structure are discussed. The main focus is on the application of Micro-Electro-Mechanical Systems (MEMS) technology, which enables fabrication of sensory structures on length-scales comparable to what can be found in nature. Its intrinsic batch fabrication capability and high spatial resolution facilitate the construction of dense arrays of flow sensors, eventually allowing the function of the fish lateral line to be copied.