
458 Biosensors Based on Nanomaterials and Nanodevices
They allow various reaction time and temperature conditions to be applied by using
capillary-driven networks. The authors also illustrated how these valves work in the
context of detecting DNA analytes using DNA probes, dyes, and receptors that were
integrated into a microuidic chip [70].
18.4.2 On-Chip Micropumps
Several different actuation mechanisms have been applied to drive the solution ow
through the microuidic devices, including pressure driven by syringe pumps [27,71]
or by gravity [72], electrokinetically driven [73], capillary driven [74], electrowetting-
based and droplet-bas