Smart hydrogel valves are a promising technology for autonomous process control, but their behaviour depends strongly on their size. At the macroscale, hydrogel valves offer high flow rates with slow response times, whereas hydrogel microvalves offer low flow rates with fast response times. This contradiction limits how far these valves can be applied in practice, particularly in industry. Scaling-up refers to the process of transferring the benefits and results of microfluidics from the laboratory scale to the production scale.
In this paper, the authors present advanced fabrication methods and corresponding concepts for scaling up responsive hydrogel microvalves, in order to achieve a higher throughput while maintaining fast response times. Using selective laser-induced etching (SLE), precise three-dimensional microfluidic structures and the corresponding molds can be produced from fused silica. This allows the hydrogel to be molded and anchored directly within the microchannel, and it enables the sizing-up of hydrogel microstructures in both the horizontal and the vertical direction.
The influence of this scaling was investigated for various hydrogel dimensions up to 1500 micrometres, with regard to their suitability for an autonomous hydrogel valve. As a proof of principle, three hydrogel valves with different depths were fabricated using this method. The response time decreases with increasing depth, while the flow rate is increased at the same time.
The study was carried out at the Institute of Microsystems Technology and the Institute of Thermal Separation Processes at the Hamburg University of Technology within the Collaborative Research Centre CRC 1615 (SMART Reactors).
Lukas Rennpferdt, Carl Linus Ehlert, Kathrin Marina Eckert, Irina Smirnova, Hoc Khiem Trieu (2026). Advanced Micromolding Approach toward Scaling-Up Smart Hydrogel Microvalves. Ind. Eng. Chem. Res.
