A bio-inspired electric camera for short-range object inspection in murky waters.

Underwater object inspection by optical sensors is usually unreliable in turbid or dark environments. Here, we designed a biomimetic 'electric camera', inspired by weakly electric fish Gnathonemus petersii, which successfully use active electrolocation for this task. The device probed nearby objects with a weak electric field and captured 'electric images' of the targets by processing the object-evoked field modulations. The camera-based electric images strongly resembled those available to G. petersii. Furthermore, by extracting the fish's analytical cues from these images, close objects could be reliably analysed. Based on the level of 'image blurring' short distances of electrolocation targets, spheres of different sizes and material were estimated. Natural targets, fish or plants, were identified irrespective of their size or distance by their two individual 'electric colours' derived from electric images. Furthermore, we introduce an image cue, called the 'electric outline', which provided information resembling a target's optical contour. Our results indicate that bio-inspired electric imaging principles provide promising cues for sensor-based, short-range object inspections in murky waters. By resembling the electric imaging applied by G. petersii our device can also be used for 'reverse biomimetics', revealing imaging cues that so far have not been considered for weakly electric fish.