Microfluidic actuation and sampling by dehydration of hydrogel

Abstract

This paper presents novel micropumps that are actuated by hydrogel drying. Gel dehydration by evaporation makes the gel absorbent. This results in the suction of the liquid from the connected microchannel into the gel. Therefore, the liquid sample flows through the microchannel as a result of this negative pressure. Micropumps with simple structures were fabricated using microfabrication techniques with glass, silicone polymer, and agarose or polyacrylamide gel. The average volume flow rate was measured in variations of several to several tens of picoliters per second according to the kind of gel. This gel micropump functioned for several hours without severe flow rate fluctuations. This pump was also able to deliver viscous fluids such as blood. This pump would be useful for microchips that need slow but steady and long-lasting actuation in the addition of sampling proteins from viscous liquids such as blood. Theoretical approach about diffusion movement of liquid into the gel was also described.