Solenoid Valves

Disclaimer

This information is provided “as-is” without any explicit or implied warranties as to its accuracy, safety, and applicability to any specific purpose. The authors and Lawrence Berkeley National Laboratory should not bear any responsibility for any use given by third parties to this information, and to the devices herein described. The user of this information and the devices herein described shall assume all risks and full responsibility for all aspects of their assembly and use.

General Info

There are many different brands and models of solenoid valves to choose from, but here we list two kinds that have worked well for us. All the valves listed in this page operate at 24V DC.

At the end of this page, there is a section that explains how to connect any of the valve manifolds to the microfluidic chips.

3-Way or 2-Way?

For operating on-chip microfluidic valves, it is imperative that you always use 3-way solenoid valves that switch the on-chip valve between two pressures: Quake-style PDMS chips need the valves to switch between high pressure and atmospheric pressure, while other types of microfluidic valves (such as those developed by Prof. Mathies at UC Berkeley) might require high pressure and vacuum, or atmospheric pressure and vacuum. All the valves listed in this page are 3-way. Do NOT use 2-way valves for these types of microfluidic devices.

Normally Open of Normally Closed?

• Normally open means that the valve has its output connected to the pressure line when the electrical power is off
• Normally closed means that the valve has its output connected to the vent line when the electrical power is off

Selecting between normally open and normally closed solenoid valves depends on how you will use the chip.

• If during an experiment the valves on the chip are closed most of the time, you should get the normally open solenoid valves
• If during an experiment, the valves on the chip are open most of the time, you should get the normally closed solenoid valves

We always use normally open solenoid valves, regardless of the operation of the chips, because they automatically set the chip to a very safe all-valves-closed state if electrical power to the solenoids fails for some reason. And our experience is that most experiments will run with most on-chip valves closed most of the time.

Festo Valves

This is now our standard brand of valve, used for all experiments, in conjuction with the Wago controllers, because it has the following advantages over the Pneumadyne brand (see below), although it is a little bit more expensive:

• Valves come with individual connectors even when they don't have a diode. This is very convenient when one wants to change a defective valve, since it doesn't require disconnecting any wires from the controller
• Manifolds can be ordered fully assembled, including connectors for all ports
• Valves have a nominal switching time of 4ms, so they can be operated at fairly high speeds

WARNING: These Festo valves can only be used with the high speed version of the USB-Based Controller or with the WAGO Controller. Do NOT use these valves with the regular speed USB Controller.

The standard 8-valve manifolds have the following part numbers, and can be bought from www.festo.com for approximately $490.00 each (as of August 2011).

• Normally open: part# 197334, type MH1-A-24VDC-N-HC-8V-PR-K01-QM-AP-BP-CX-DX
• Normally closed: part# 197334, type MH1-A-24VDC-C-HC-8V-PR-K01-QM-AP-BP-CX-DX

These part numbers correspond to manifolds that come with 1m long cables, 1/4" push-in connectors for the supply and exhaust ports, and 5/32" push-in connectors for the output ports ("working" ports in Festo's terminology), as shown in the following images. Each one of these solenoid valves consumes 0.042A.

These valves can be connected to the high speed USB-Based Controller using the same 10-pin, 0.1", female connector housing and female connector terminals listed in the parts lists for Pneumadyne Valves shown below. The assembly of this 10-pin connector can be seen in the USB-Based Controller page.

Pneumadyne Valves

We used this brand at the Quake Lab for a long time and it works very well, but they don't sell a model with a connector and no diode, so the diode-less valves would require disconnecting at the controller when changing a defective or damaged valve (a difficult thing to do with the USB controller, unless you manually put a connector on each valve). Additionally, they have switching times that are double that of the Festo valves (~8ms).

The following spreadsheet contains a list of the part numbers needed to build manifolds with Pneumadyne valves. If you will use these valves with the USB-Based Controller, you must select the type of valve corresponding to the controller you are building (low or high speed), and whether you want normally open or normally closed valves (all prices as of July 2011). The USB-Based Controller page explains how to wire the valves to connect them to the USB Controller using the 10-pin female connector listed below.

SMC Valves

In some countries it will be difficult to find the Festo or Pneumadyne valves, so an alternative supplier is SMC Corp. We have never used this brand of valves, but they should work fine. The SMC valve type most similar to the Festo or Penumadyne ones belongs to the SY100 series. The part numbers that would seem to work well are as follows:

• Valves (base mounted, normally open, 24Vdc, plug connector with lead wire, with light/surge suppressor for use with the low speed USB controller): SY124-5MZ
• Valves (base mounted, normally open, 24Vdc, NO light or surge suppressor for use with the high speed USB or WAGO controllers): SY124-5M
• NOTE: For normally closed valves, change the SY124 to SY114 in the part number
• 8-valve manifold: SS3Y1-S41-08-M3

WARNING: We have never used these valves, so the part numbers above might not be totally accurate. We created the part numbers by looking at the SY100 series catalog. If you intend to buy these types of valves, please double check the part numbers in the catalog, which is available on-line.

You will need fittings with metric threads to connect these manifold to the chips (M3x0.5) and to the pressure source (M5x0.8). You can easily find metric fittings that are equivalent to those on the parts list for the Pneumadyne valves.

Connecting the Solenoid Valves to the Chips

The following parts are needed to connect the valve manifolds to the chips (the 1/4" tube is for connecting the manifold to the pressure source). All prices as of July 2011.