Figure 1.

(a) Schematic of the one-dimensional metamaterial [5]. Each element (red), of mass m, has a natural spacing of Δ. Each mass is connected to an external wall by a bistable elastic element (green) and to neighbouring elements by linear elastic springs (blue). The inset shows both stable states for each element, u_i(t) =  ± δ where i is the mass index. (b) An example of bistable potential function (red) and its derivative (blue) for a_i =  − 0.5 and δ = 1 in the inactive model, or the active model at t = 0. (b–d) The effect of the biological reaction mechanism, which resets the potential function. Note that (d) corresponds to a reflection of (b) about u_i = 0. For each plot, the stable steady states (dashed grey) and unstable steady state (dotted grey) are shown. (e,f ) Signal propagation through this material showing (e) the displacement of each element, u_i(t), and (f ) the biological reaction, a_i(t). The signal was initiated by moving the first element from a displacement of −δ to δ at t = 0, and was retransmitted by moving the last element from a displacement of δ to −δ at t = 400. We note the original signal could also be initiated from the right boundary by moving the last element from a displacement of −δ to δ, or indeed anywhere in the domain. Parameters used are m = 1 g, k = 1 g m s⁻², γ = 1 g s⁻¹, Δ = 0.002 m, δ = 1 m, ϵ = 0.01/s, η = 2, v = 1 g/(m² s²) and N = 101 masses. (Online version in colour.)