Functional hydrogel structures for autonomous flow control inside microfluidic channels

• Published in: Nature (London) Vol. 404; no. 6778; pp. 588 - 590
• Main Authors: Beebe, David J, Moore, Jeffrey S, Bauer, Joseph M, Yu, Qing, Liu, Robin H, Devadoss, Chelladurai, Jo, Byung-Ho
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 06.04.2000; Nature Publishing Group
• Subjects: Applied fluid mechanics; Exact sciences and technology; Fabrication; Flow control; Fluid dynamics; Fluidics; Fundamental areas of phenomenology (including applications); Nanotechnology; Physics; Polymers; Regulated flow; Fabrication; Autonomous system; Actuators; Flow control; Hydrogel; Microstructure; Fluidics
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/35007047

Hydrogels have been developed to respond to a wide variety of stimuli, but their use in macroscopic systems has been hindered by slow response times (diffusion being the rate-limiting factor governing the swelling process). However, there are many natural examples of chemically driven actuation that rely on short diffusion paths to produce a rapid response. It is therefore expected that scaling down hydrogel objects to the micrometre scale should greatly improve response times. At these scales, stimuli-responsive hydrogels could enhance the capabilities of microfluidic systems by allowing self-regulated flow control. Here we report the fabrication of active hydrogel components inside microchannels via direct photopatterning of a liquid phase. Our approach greatly simplifies system construction and assembly as the functional components are fabricated in situ, and the stimuli-responsive hydrogel components perform both sensing and actuation functions. We demonstrate significantly improved response times (less than 10 seconds) in hydrogel valves capable of autonomous control of local flow.