Fundamentals of Hydrogel-Based Valves and Chemofluidic Transistors for Lab-on-a-Chip Technology: A Tutorial Review

Abstract

Stimuli-sensitive hydrogels have an outstanding potential for miniaturized, integrated sensor, and actuator systems and especially for lab-on-chip technology, but the application is still in its infancy. One major reason may be that design and realization of hydrogel-based systems are exceptionally complex and demanding. Here, the design parameters of a key component, the hydrogel-based valve, are discussed in their entirety. Key developments in the fields of stimuli-sensitive hydrogels are highlighted and the necessary know-how in material behavior, microstructuring technologies, modeling and name five essential design guidelines as well as scaling laws for hydrogel-based components, including microfluidic one-directional valves, microelectromechanical systems valves, self-regulating, chemomechanical valves, and chemofluidic transistors, is provided.