Remote electrical sensing: Detection and analysis of objects by weakly electric fishes

Abstract

With a special electric organ, weakly electric fish emit electric signals, each of which builds up an electric field around them in the water. To sense locally occurring voltages caused by their own signals, the fish use thousands of electroreceptor organs distributed over their skin. Nearby objects are detected because they distort the self-produced electric field and thus project electric images onto the array of electroreceptors. By analysing these electric images, the fish can detect and localize objects in the water and recognize their electrical and spatial properties. Inspired by these remarkable capabilities of weakly electric fish, we designed technical sensor systems that can solve similar sensing problems. We applied the principles of active electrolocation by building devices that produce electrical current pulses and simultaneously sense local current densities. Depending on the specific task, sensors can be designed which (i) detect an object, (ii) localize it in space, (iii) determine its distance and (iv) measure its electrical properties. Our biomimetic sensor systems proved to be insensitive to environmental disturbances such as heat, pressure or turbidity. They can be used in a wide range of applications, such as material identification, remote distance measurements and medical diagnostics.