Neuromorphic engineering promises to have a revolutionary impact in our societies. A strategy to develop artificial neurons (ANs) is to use oscillatory and excitable chemical systems. Herein, we use UV and visible radiation as both excitatory and inhibitory signals for the communication among oscillatory reactions, such as the Belousov-Zhabotinsky and the chemiluminescent Orban transformations, and photo-excitable photochromic and fluorescent species. We present the experimental results and the simulations regarding pairs of ANs communicating by either one or two optical signals, and triads of ANs arranged in both feed-forward and recurrent networks. We find that the ANs, powered chemically and/or by the energy of electromagnetic radiation, can give rise to the emergent properties of in-phase, out-of-phase, anti-phase synchronizations and phase-locking, dynamically mimicking the communication among real neurons.

This work is an important contribution to the development of neuromorphic engineering based on solutions of nonlinear chemical systems. It reports the results of experiments and simulations regarding the optical communication between the Belousov-Zhabotinsky reaction and photochromic and luminescent materials. It demonstrates that thermally reversible photochromic and luminescent compounds are dynamic models of phasic photo-excitable neurons. Moreover, it shows that photoreversible photochromic compounds can be used for the implementation of optical synapsis and memory effects. Finally, it reports the first example of transmission of a chaotic signal between a Hydrodynamic Photochemical Oscillator based on a photochromic naphthopyran and a luminescent acridinium salt.

This work demonstrates the computational power of a hydrodynamic photochemical oscillator based on a photochromic naphthopyran generating aperiodic time series. The chaotic character of the time series is tested by calculating its largest Lyapunov exponent and the correlation dimension of its attractor after building its phase space through the Takens' theorem. Then, the chaotic dynamic is shown to be suitable to implement all the fundamental Boolean two-inputs-one-output logic gates. Finally, the strategy to implement fuzzy logic systems (FLSs) based on the time series is described. Such FLSs promise to be useful in the field of computational linguistics, which is concerned with the development of artificial intelligent systems able to transform collections of numerical data into natural language texts.

Neuromorphic engineering promises to have ar evolutionary impact in our societies.Astrategy to develop artificial neurons (ANs) is to use oscillatory and excitable chemical systems.H erein, we use UV and visible radiation as both excitatory and inhibitory signals for the communication among oscillatory reactions,s uch as the Belousov-Zhabotinsky and the chemiluminescent Orban transformations,a nd photo-excitable photochromic and fluorescent species.W e present the experimental results and the simulations regarding pairs of ANs communicating by either one or two optical signals,a nd triads of ANs arranged in both feed-forwarda nd recurrent networks.W efind that the ANs,powered chemically and/or by the energy of electromagnetic radiation, can give rise to the emergent properties of in-phase,out-of-phase,anti-phase synchronizations and phase-locking, dynamically mimicking the communication among real neurons.The human brain and intelligence are drawing attention because their operation is inspirational in various disciplines that deal with complexity. [1] Chemists,i nc ollaboration with colleagues of other disciplines,a re contributing to the development of neuromorphic engineering. [2,3] Neuromorphic engineering implements surrogates of neurons through nonbiological systems either for neuro-prosthesis [4] or to devise brain-like computing machines.B rain-like computing machines will exhibit the peculiar performances of human intelligence,s uch as learning, recognizing variable patterns and computing with words as some programs have commenced to do.H owever, it is expected that brain-like computers will have the advantage of requiring much less power and occupying much less space than our best electronic supercomputers.S urrogates of neurons for brain-like com-puters can be implemented by using either conventional passive and active circuit elements, [5] or two-terminal devices with an on-volatile adjustable internal state such as memristive components, [6] or oscillatory and excitable chemical reactions. [7] In this work, we use oscillatory reactions [8] (Osc) and excitable photochromic or luminescent species (Exc) as artificial neuron (AN) models and we study their communication through UV/visible radiation.Neurons are nonlinear dynamic systems that, usually, synchronize when they communicate. [9] Therefore,t o approach the computational capabilities of the human brain, it is useful to implement and study the synchronization of nonlinear chemical systems.Nonlinear chemical systems have been typically coupled through continuous mass exchange, [10] electrochemical linkage, [11] or mechanical/light-induced pulsed release of chemicals. [12] Herein, we propose the use of UV/visible radiation as excitatory and inhibitory optical signals that allow us to establish in-phase,anti-phase,oroutof-phase synchronizations and phase-locking. Ther esults of experiments and simulations are presented, regarding the optical communication between two ANs and either one or two optical signals (S), and between three ANs organized in eit...

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