This page discusses different ways of controlling on-chip microfluidic valves from a computer (these can be Quake-style valves made by Multi-Layer Soft Lithography, Mathies-style ones made of a glass-PDMS-glass sandwich, or any other type of microfluidic valve actuated by pressure and/or vacuum). For manual control of the valves, you can refer to these two pages of instructions posted at the Stanford Microfluidics Foundry.
The following is a list of different devices I recommend for setting up a computer-based valve controller, but this does not mean that there aren't other options available or that other options won't work well. These devices are simply my favorites.
You are encouraged to leave comments at the bottom of each page, if you have questions about the construction, setup, and use of these valve controllers, and especially if you have suggestions on how to improve things.
This currently is our favorite option because it doesn't require any circuit assembly and is very scalable, but it is the most expensive. This setup is based on modular industrial automation components made by WAGO. The core of the setup is an Ethernet-based programmable controller (WAGO-I/O-SYSTEM 750) and any number of 4-channel digital output modules that connect to the controller and can drive the solenoids directly. These components require only minimal assembly, can accomodate as few or as many digital I/O modules as necessary, and the modules can be easily added at any time to expand the number of solenoids. WAGO makes a large variety of expansion modules that can perform many other tasks, such as analog I/O, pulse-width modulation, stepper motor control, etc. so you can build a very powerful instrumentation system with a single controller. Additionally, because the controller is programmable (using CoDeSys), it can perform many automation processes by itself (including reacting to sensor signals collected by extra instrumentation modules), increasing speed and freeing the computer from some tasks.
This option is based on an off-the-shelf USB to digital I/O circuit (sold to electronics hobbyists) connected to a custom-designed circuit that uses the 5V digital outputs from the USB device to switch 24V solenoid valves. This option is relatively cheap and very easy to use, but you will have build the custom circuit, based on the instructions provided here. The construction requires basic electronic soldering skills, and a little bit of machining (drilling holes and milling a slot) for making the enclosure box. One controller box can drive 24 solenoids, so you will have to build more than one box if you have to drive more than 24 solenoids. This controller has been very popular for a few years, and the information for building it used to be posted on the Stanford Microfluidics Foundry website before it was moved here and improved.
The Solenoid Valves page describes different brands of pneumatic solenoid valves that work well for controlling microfluidic devices. After building one of the two controllers described above, you have to choose solenoid valves to go with it.
The Pressure Control page has information about the regulators and accessories needed to generate the pressure needed to actuate Quake-style microfluidic valves.