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. Author manuscript; available in PMC: 2016 Mar 21.
Published in final edited form as: Lab Chip. 2015 Mar 21;15(6):1432–1444. doi: 10.1039/c4lc01155d

Figure 1.

Figure 1

The valving and automation toolkit. All valves make use of absorbent expandable elements as actuators. Valves can be broadly classified into two categories – A. those that actuate after a fixed period of time and make use of an external fluid for actuation, and B. those that actuate after a fixed volume of fluid flow and make use of an internal process fluid for actuation. Time-metered valves consist of A1. On-switches that start fluid flow between two channels, A2. Off-switches that stop fluid flow between two channels, and A3. Diversion-switches that divert fluid flow from one channel to another. Volume-metered valves demonstrated here are diversion switches that use two different mechanisms: B1. Moving channels with fixed volume-metering pads, and B2. Fixed channels with moving volume-metering pads.