סמינר לפיזיקה של מערכות ביולוגיות וחומרים רכים: Liquid Z-Diodes

Abstarct:

Zener diodes (Z-diodes) are often used as voltage regulators, and are designed to operate in reverse breakdown. Namely, they can conduct current in the reverse direction when a certain voltage, known as the Zener voltage, is applied. Analogous to electric diodes, liquid diodes are microscale surface structures that promote spontaneous unidirectional flow. In nature, they are used for water collection and uptake, reproduction, and feeding. While such structures are usually deterministic, that is, used to guide liquids in specific directions and prevent backflow, the ability to render them responsive to external stimuli holds a great potential for controlling, actuating and manipulating pump-free liquid flow in capillary networks.

Inspired by electric Z-diodes, we demonstrate break of diodicity in flexible liquid diodes in response to external stimuli. Specifically, we use elastic deformations and we identify two physical mechanisms to break the diodicity. Namely, by compressing or bending the liquid diodes, the formation of a capillary bridge in the backward flow direction is induced. Diodicity breaks locally, where the liquid front is located, without influencing other diodes. This groundbreaking concept demonstrates sequence-dependent liquid propagation in capillary networks, paving the way for implementing memory, reaction-dependent actuation, and designing circuit-inspired capillary liquid networks.