Nature is full of exemplary species that have evolved personalized sensors and actuating systems that interface with and adapt to the world around them. Among them, cephalopods are unique. They employ fast-sensing systems that trigger structural changes to impart color changes through biochemical and optoelectronic controls. These changes occur using specialized optical organs that receive and respond to signals (light, temperature, fragrances, sound, and textures) in their environments. We describe features that enable these functions, highlight engineered systems that mimic them, and discuss strategies to consider for future cephalopod-inspired sensor technologies.

Membranes of poly(vinylidene difluoride) (PVDF) and related polymers are used as piezoelectric materials to decompose rhodamine B (RhB) under low power sonication. The change in the visible spectrum of RhB allows determination of the rate constants for different polymer compositions and membrane thicknesses. The results indicate that the piezoelectric field generated by mechanical deformation of the polymers catalyzes the scission of the C−N bond in RhB. When PVDF is doped with transition-metal nitrates to increase the fraction of the piezoelectric β-phase, the rate constants increase, but the analysis is complicated by concurrent adsorption of RhB onto the membrane. A mechanism consistent with the observed data is proposed where the piezocatalytic effect of the membrane is to heterolytically cleave the C−N bond followed by formation of a C−Cl bond on the new xanthene ring.

The products of thermal decomposition of iron nitrate nonahydrate doped into poly(vinylidene difluoride) are examined using Mössbauer spectroscopy. Very little of the expected nitrogen dioxide product is observed, which is attributed to Fe3+ catalysis of the decomposition of NO2. The active site of the catalysis is shown to be Fe(OH)3 in the polymer matrix, which is, unexpectedly, reduced to Fe(OH)2. Thermodynamic calculations show that the reduction of Fe3+ is exergonic at sufficiently high temperatures. A reaction sequence, including a catalytic cycle for decomposition of NO2, is proposed that accounts for the observed reaction products. The role of the polymer matrix is proposed to inhibit transport of gas-phase products, which allows them to interact with Fe(OH)3 doped in the polymer.

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