A easily manipulative stimuli-responsive micro-valve array

Integrative micro-valve array is one of useful tools for the drug discovery, high-throughput screening. In this paper, we have developed a low-cost and easily manipulative pH-responsive micro-valve array. To prove the feasibility, we designed and fabricated the double micro-valves array, the tetrad micro-valves array and the octad micro-valves array. The platform of arrayed valve was fabricated by using polydimethylsiloxane (PDMS) and the microsphere utilized as an actuating element was produced via “on the fly” photopolymerization method. The microspheres were manually incorporated into the arrayed PDMS platform. To construct the platform of valve arrays, we stacked 3 thin (thickness: around 140μm), patterned PDMS layers (holelayer, membrane-layer, and upper-layer) and one PDMS basrelief plate (thickness: around 8 mm), and the top was covered with the cover slip. The actuating pH-responsive microspheres (diameter: around 140μm) were incorporated into the microvalve units and they are located in the 700μm interval. Each valve unit was controlled to be opened and be closed by changing pH solutions passing through it. The operation and the function of the fabricated micro-valve arrays were evaluated through the diverse experiments. The integrated system was operated expediently and functioned well. The closing and opening times were around 50s and 60s, respectively. Sample solution-flow rate is 0.03 ml/min when the pressure is 50kPa operated by varying the height of water column. Linear flow control was achieved over a wide range of operating flow rates. Furthermore the fabrication process of pH-responsiveactuated micro-valve arrays using PDMS is simple and its performance is suitable for a disposable lab-on-a-chip. These stimuli-responsive micro-valves do not use any electrical or mechanical components, and have many potential applications.