Andreas Richter

Photolithographic patterning of components and integrated circuits based on active polymers for microfluidics is challenging and not always efficient on a laboratory scale using the traditional mask-based fabrication procedures. Here, we present an alternative manufacturing process based on multi-material 3D printing that can be used to print various active polymers in microfluidic structures that act as microvalves on large-area substrates efficiently in terms of processing time and consumption of active materials with a single machine. Based on the examples of two chemofluidic valve types, hydrogel-based closing valves and PEG-based opening valves, the respective printing procedures, essential influencing variables and special features are discussed, and the components are characterized with regard to their properties and tolerances. The functionality of the concept is demonstrated by a specific chemofluidic chip which automates an analysis procedure typical of clinical chemistry and laboratory medicine. Multi-material 3D printing allows active-material devices to be produced on chip substrates with tolerances comparable to photolithography but is faster and very flexible for small quantities of up to about 50 chips.

Dielectric elastomers (DEs) are electroactive polymers commonly used in soft robotics. Bulky and stiff high‐voltage circuits are usually needed to control their operation. This article presents autonomous control in a multi‐functional device made entirely of DEs. A gripper made of DE actuators is controlled by dielectric elastomer sensors through an electrical circuit. The circuit itself is composed of a network of actuators and sensors. The final structure requires only a constant power supply to work and produces its controlling signals. Every component can be manufactured simultaneously with the same materials and processes. At first, the logical control of the gripper is demonstrated by directly connecting a sensor to the gripper that opens when the sensor is stretched. Then, a DE level‐triggered flip‐flop (also called latch) is introduced to have bi‐stability between open and closed states. Finally, the latch is integrated inside the gripper, allowing it to sense objects. The device autonomously grips an object that is placed in it, resembling the closing mechanism of the plant Dionaea muscipula , also known as the Venus flytrap.