High Integration of Microfluidic Circuits Based on Hydrogel Valves for MEMS Control

Abstract Integrated circuits (ICs) are the key to powerful microarchitectures for lab on a chip applications. High actuator densities can enable the control of several thousand of reactions executed in parallel on a single chip. Hydrogels can act as self‐contained sensor–actuator materials, which control fluid flows depending on local physicochemical conditions. A concept is described for the preparation of highly integrated circuits based on stimuli‐sensitive hydrogels. The concept allows to adjust the working point and fulfill the free swelling condition of the hydrogels, which is favorable for the dynamic performance of the actuators. The components are polymerized on a glass substrate, which is also used to seal the microfluidic system. Therefore, the hydrogel integration is conducted within the standard microfluidic system set‐up procedure. For a first demonstration integration densities of microfluidic valves of up to 172 gels cm−2 in a single microfluidic circuit are realized. Furthermore, control of microfluidic valves fabricated by the demonstrated high integration procedure via an optoelectrothermic transducer setup is shown.