Routing Physarum with Electrical Flow/Current

Abstract

Plasmodium stage of Physarum polycephalum behaves as a distributed dynamical pattern formation mechanism, where foraging and migration is influenced by local stimuli from a range of attractants and repellents. Complex protoplasmic tube network structures are formed as a result, which serve as ‘circuits’ by which nutrients are distributed. In this paper, the authors investigate whether this ‘bottom-up’ circuit routing method may be harnessed in a controllable manner as a possible alternative to conventional template-based circuit design. They interfaced the plasmodium of Physarum polycephalum to the planar surface of the spatially represented computing device (Mills’ Extended Analog Computer—EAC), implemented as a sheet of analog computing material. The authors presented a pattern of current distribution to the array and found that they could select the directional migration of the plasmodium growth front by exploiting plasmodium electro-taxis toward current sinks. They utilised this directional guidance phenomenon to route the plasmodium across its habitat and around obstacles represented by repellent current sources. These findings demonstrate proof of concept in the low-level dynamical routing for biologically implemented circuit design.