Physarum polycephalum was widely used for the realization of systems for unconventional computers. The integration of this living being into electronic or optical devices will increase the computational capabilities. In this chapter we will discuss several systems where the slime mold was interfaced with organic electronics devices. In particular, we will demonstrate the realization of slime mold Schottky diode and organic electrochemical transistor. A central part of the chapter is dedicated to the integration of the Physarum polycephalum into organic memristive device electronic element with synapse-like properties. We have described an architecture and working principles of the device as well as variations of its electrical and optical properties as a result of the interaction with slime mold. As it was demonstrated by the presented results, Physarum polycephalum slime mold can be considered as a smart candidate for the implementation of functional properties of smart living systems into electronic devices.

Spacetime computing is undoubtedly one of the most ambitious and less explored forms of unconventional computing. Totally unconventional is the medium on which the computation is expected to take place - the elusive texture of physical spacetime - and unprecedentedly wide its scope, since the emergent properties of these computations are expected to ultimately reproduce everything we observe in nature. First we discuss the distinguishing features of this peculiar form of unconventional computing, and survey a few pioneering approaches. Then we illustrate some novel ideas and experiments that attempt to establish stronger connections with advances in quantum gravity and the physics of spacetime. We discuss techniques for building algorithmic causal sets - our proposed deterministic counterpart of the stochastic structures adopted in the Causal Set programme for discrete spacetime modeling - and investigate, in particular, the extent to which they can reflect an essential feature of continuous spacetime: Lorentz invariance.

Slime mold Physarum polycephalum is a single cell visible by an unaided eye. The slime mold optimizes its network of protoplasmic tubes to minimize expose to repellents and maximize expose to attractants and to make efficient transportation of nutrients. These properties of P. polycephalum, together with simplicity of its handling and culturing, make it a priceless substrate for designing novel sensing, computing and actuating architectures in living amorphous biological substrate. We demonstrate that, by loading Physarum with magnetic particles and positioning it in a magnetic field, we can, in principle, impose analog control procedures to precisely route active growing zones of slime mold and shape topology of its protoplasmic networks.

The plasmodium of Physarum polycephalum is a large single cell visible with the naked eye. The plasmodium realizes a pattern of protoplasmic veins which span sites of sources of nutrients, producing efficient network structures like cycles and Steiner minimum trees. Besides, the plasmodium can embed different chemicals; therefore, it should be possible to program the plasmodium to realize deterministic adaptive network and spatial distribution of nanoscale and microscale materials. The transported particles can be used for the modification of the physical properties of the system (electrical, optical, magnetic) facilitating the readout of the information, processed by the slime mold. Experiments with polystyrene microparticles and MnCO3 microparticles demonstrate that the plasmodium of Physarum can propagate nanoscale objects using a number of distinct mechanisms. The results of our experiments could be employed in the field of the unconventional computing and bio-computing application devices, using Physarum network as scaffolds for the development of hybrid nanocircuits and microcircuits and devices.

Research in unconventional, or nature-inspired, computing aims to uncover novel principles of efficient information processing and computation in physical, chemical and biological systems, to develop novel non-standard algorithms and computing architectures, and also to implement conventional algorithms in non-silicon, or wet, substrates. This emerging field of science and engineering is predominantly occupied by theoretical research, e.g. quantum computation, membrane computing and dynamical systems computing.

European Support for Unconventional Computation, "Physarum Chip Project: Growing Computers From Slime Mould"