Neuromorphic Engineering in Wetware: Discriminating Acoustic Frequencies through Their Effects on Chemical Waves.

Some features of the human nervous system can be mimicked not only through software or hardware but also through liquid solutions of chemical systems maintained under out-of-equilibrium conditions. We describe the possibility of exploiting a thin layer of the Belousov-Zhabotinsky (BZ) reaction as a surrogate for the cochlea for sensing acoustic frequencies. Experiments and simulations demonstrate that, as in the human ear where the cochlea transduces the mechanical energy of the acoustic frequencies into the electrochemical energy of neural action potentials and the basilar membrane originates topographic representations of sounds, our bioinspired chemoacoustic system, based on the BZ reaction, gives rise to spatiotemporal patterns as the representation of distinct acoustic bands through transduction of mechanical energy into chemical energy. Acoustic frequencies in the range 10-2000 Hz are partitioned into seven distinct bands based on three attributes of the emerging spatiotemporal patterns: (1) the types and frequencies of the chemical waves, (2) their velocities, and (3) the Faraday waves' wavelengths.

Morphogenesis in Synthetic Chemical Cells.

We present an efficient model for describing morphogenesis and the emergence of spatiotemporal structures in synthetic chemical cells. This work is motivated by an experimental setup used for testing Turing's theory of morphogenesis. The model developed is based on the general theory of chemically active droplets, which combines the classical theory of phase separation with reaction-diffusion systems. Through the 2D calculations, we find the six spatiotemporal structures predicted by Turing in 1952 and experimentally observed, in a 1D array of droplets. Moreover, under Turing instability, with a determined chemical wavelength, the system undergoes morphogenesis. This theoretical approach provides a useful tool for understanding the physical differentiation through the direct calculation of the osmotic pressure in each cell as the chemical reaction occurs.

Turing patterns modulation by chemical gradient in isothermal and non-isothermal conditions.

The modulation of Turing patterns through Dirichlet boundary conditions has been studied through the isothermal and non-isothermal versions of a Brusselator-like model in a small-size domain reactor. We considered the Minkowski functional and the rate of entropy production to characterize the morphological aspects of the patterns and to indicate transitions of spatial states. We find that boundary conditions can induce the spatial symmetry breaking of Turing patterns when they are defined around the equilibrium points of a homogeneous dynamical system. As a result, two different Turing patterns can emerge in a reactor under an imposed gradient of chemicals that contains the equivalent concentration of the equilibrium points at some point in the boundary.