Home > Research Papers > Adamatzky: Slime Mould Tactile Sensor

Adamatzky: Slime Mould Tactile Sensor

2013 June 6

Figure 7. Physarum’s morphological responses towards mechanical contact. (a) A protoplasmic tube is distorted by a glass capillary placed across the tube. (b) A zone of extensive growth of Physarum under and at the edges of the glass capillary. (c) Two segments of glass capillary placed on top of Physarum, on agar blob, are partly colonised by the slime mould. (d) Physarum colonises plastic disc placed on top of Physarum sheet wrapping agar blob, view from below.

Slime mould P. polycephalum is a single cells visible by unaided eye. The cells shows a wide spectrum of intelligent behaviour. By interpreting the behaviour in terms of computation one can make a slime mould based computing device. The Physarum computers are capable to solve a range of tasks of computational geometry, optimisation and logic. Physarum computers designed so far lack of localised inputs. Commonly used inputs illumination and chemo-attractants and repellents usually act on extended domains of the slime mould’s body. Aiming to design massive-parallel tactile inputs for slime mould computers we analyse a temporal dynamic of P. polycephalum’s electrical response to tactile stimulation. In experimental laboratory studies we discover how the Physarum responds to application and removal of a local mechanical pressure with electrical potential impulses and changes in its electrical potential oscillation patterns.

Andrew Adamatzky

In a series of previous works, see overview in [2], we developed a concept and fabricated experimental laboratory prototypes of amorphous bio-computing devices Physarum machines. A Physarum machine is a programmable amorphous biological computing device experimentally implemented in plasmodium of P. polycephalum. Physarum polycephalum belongs to the species of order Physarales, subclass Myxogastromycetidae, class Myxomycetes, division Myxostelida. It is commonly known as a true, acellular or multi-headed slime mould. Plasmodium is a `vegetative’ phase, a single cell with a myriad of diploid nuclei. The plasmodium is visible to the unaided eye. The plasmodium looks like an amorphous yellowish mass with networks of protoplasmic tubes. The plasmodium behaves and moves as a giant amoeba. It feeds on bacteria, spores and other microbial creatures and micro-particles [30]. The plasmodium’s foraging behaviour can be interpreted as a computation: data are represented by spatial distribution of attractants and repellents, and results are represented by a structure of Physarum’s protoplasmic network. In such speci cation a plasmodium can solve computational problems with natural parallelism, including optimisation on graphs, computational geometry, logic and robot control, see details in

A Physarum machine is programmed by confi gurations of repelling and attracting gradients: chemical substances, temperature and illumination. These quantities are often difficult to localise, which makes a precise, fi ne-grained, input of spatial data into Physarum machines problematic. A tactile input of information could be a solution. Thus in present we evaluate a feasibility of Physarum to act as a tranducer: to transform a tactile stimulation or a mechanical pressure to a distinctive pattern of an electrical activity. We study how parameters of the oscillations change in response to an application and removal of a solid light-weight insulators to Physarum’s protoplasmic tubes or sheet-shaped parts

Plasmodium of Physarum polycephalum was cultivated in plastic lunch boxes (with few holes punched in their lids for ventilation) on wet kitchen towels and fed with oat flakes.

Physarum Machines (YouTube)
http: //www.youtube.com/user/PhysarumMachines.

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