Performing calculus: Asymmetric adaptive stimuli-responsive material for derivative control

Abstract

Materials (e.g., brick or wood) are generally perceived as unintelligent. Even the highly researched “smart” materials are only capable of extremely primitive analytical functions (e.g., simple logical operations). Here, a material is shown to have the ability to perform (i.e., without a computer), an advanced mathematical operation in calculus: the temporal derivative. It consists of a stimuli-responsive material coated asymmetrically with an adaptive impermeable layer. Its ability to analyze the derivative is shown by experiments, numerical modeling, and theory (i.e., scaling between derivative and response). This class of freestanding stimuli-responsive materials is demonstrated to serve effectively as a derivative controller for controlled delivery and self-regulation. Its fast response realizes the same designed functionality and efficiency as complex industrial derivative controllers widely used in manufacturing. These results illustrate the possibility to associate specifically designed materials directly with higher concepts of mathematics for the development of “intelligent” material-based systems.

A wave-confining metasphere beamforming acoustic sensor for superior human-machine voice interaction

“…Without affecting the acoustic beamforming structure, both the intrinsic SNR and sensitivity of single piezoelectric acoustic transducers are substantially improved at the same time. For future designs, we could combine adaptive stimuli-responsive materials (42,43) as the local resonators in metamaterials to actively tune the bandgap according to needs. Furthermore, by choosing appropriate materials, it is possible for MBAS to shrink in size with similar performance, extending the application fields to small-scale robotics and health monitoring (44)(45)(46).…”

Flytrap Inspired pH‐Driven 3D Hydrogel Actuator by Femtosecond Laser Microfabrication

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Soh et al used an asymmetric stimulus response to link the concepts of materials and mathematics, giving the hydrogel the ability to handle time derivatives. [12] These asymmetric actuators can be driven by external stimuli, such as light, temperature, pH, and magnetic fields to produce on-demand deformation with specific functions. [13][14][15][16] For the construction of the asymmetric actuators, the general fabrication methods include UV-assisted printing, fused deposition modeling (FDM), femtosecond laser direct writing (FsLDW), etc.

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