by Jenny Knodell, IQS Editor
Based solely on the way ‘membrane switch’ sounds, I would think it was some sort of futuristic half-biological half-electronic device used in laboratories; definitely not something I’ve come across in my everyday life. In reality, they are very simple and common aspects of technology, and they are used by anyone that cooks—actually, anyone that heats up food…or uses a phone. Basically, if you don’t live in a third world country, you push membrane switches every single day that you get out of bed. Those flat, thin electronic buttons on your microwave, stove, dishwasher, security system, TV remote, cell phone and landline phone are what I’m talking about. They activate functions performed by electronic equipment through a rather straightforward process. Although they are considered recent technology, membrane switches use a very simple electronic concept in a highly complex and advanced manner.
In its simplest form, membrane switches are composed of a two layer assembly, but the standard is five. The first layer is the decorative and informative graphic overlay. It is generally made of thin plastic material with a screen printed design. Durability is important for this layer, since it is the only one exposed to the outside. Under the front layer we find the membrane layer, one of the two required components. It carries at least one of the poles of the switch or a conductive shorting pad. The third layer contains small metal domes that are placed above each connecting circuit. They are kept in place by an adhesive. The static layer, like the second, carries the poles of the switch or a conductive shortening pad. It is also required. Finally, a rigid layer composes the bottom. The static layer is laminated to hard material like metal, glass or fiberglass, which is considered the instrument housing.
All of these layers work together to form a push-activated signal that can do anything from heating your leftovers to changing the channel, much like the writers of The Jetson’s used to imagine in the 50s. Membrane switches have been around since the 80s, and before that, push buttons were mainly used. These have been mostly phased out because they are more expensive to produce, are less protected from dirt and moisture and are more prone to mechanical failure than membrane switches. In the same vein of technology lies touch screens, which have been around since the 60s but gained massive popularity within the last decade or so. These computer screens are also pressure sensitive and can detect the presence and location of human touch without any sort of poles, pads or domes. Touch screens are used by almost every cashier and wait staff in the country, and more recently, the Apple iPhone and iPod have replaced membrane switches with touch screens. They are now even found in newer car models, aircrafts, gaming consoles, appliances and handheld electronics of every kind. Could touch screens eventually replace membrane switches altogether? It’s anyone’s guess, but since they both have their own advantages and draw backs, I think they’ll both be around for a long time.