12-button, embossed key, membrane switch with integrated window, designed and manufactured for Baxter Healthcare

Electrical switches are used in nearly all electronic devices. You’ll find them in household appliances, remote controls, TVs, human machine interfaces (HMIs) and more. Not all electrical switches are the same, however. Membrane switches, for instance, feature a unique design that involves the use of a flexible substrate. To learn more about membrane switches and how they work, keep reading.

What Is a Membrane Switch?

A membrane switch is an electrical switch that, like other electrical switches, is used to control an electrical circuit. It features a conventional open and closed design. When a membrane switch is open, the circuit is incomplete. When it’s closed, the circuit is complete. Membrane switches are distinguished from other types of electrical switches, however, because of their flexible construction.

By definition, an electrical switch is considered a membrane switch if at least one of its electrical contacts is made of a flexible material or placed on a flexible substrate. Some membrane switches have a single flexible contact, whereas others have two flexible contacts. Regardless, they all have at least one flexible contact, which is responsible for opening and closing the circuit.

How Do Membrane Switches Work?

Membrane switches work in a similar way as most other electrical switches, including mechanical switches. They feature two electrical contacts that are separated by a small layer of air.

When you press a button — typically a graphic layer featuring the button’s icon or design — the top contact will press into the bottom contact. Once the two electrical contacts meet, the circuit closes to become complete. And when you release your finger from the button, the two electrical contacts pull away from each other to break the circuit.

Most membrane switches use conductive ink for the circuit. Copper, graphite and silver, for instance, is often used as the ink filler. All three of these metals have excellent electrical conductivity, so the electricity can travel through them with relative ease.

What Are the Benefits of Membrane Switches?

Membrane switches have become a popular alternative to mechanical switches for several reasons. For starters, they can typically withstand moisture and humidity without suffering damage. The top layer is sealed, so moisture can’t enter and reach the circuity.

Backlighting can also be used in conjunction with membrane switches to enhance their aesthetics and functionality. Electroluminescent (EL) and light-emitting diode (LED) are two common backlighting solutions for membrane switches. There’s also fiber optic backlighting, which is typically used with LED.