In Assistive Technology, one of the major areas that is considered for people with significant disabilities is switch access. Using a capability switch or accessibility switch, someone can control their environment, play with a toy, use a computer, or communicate. All manner of switches are available commercially - switches that work on mouth pressure, fingers, muscle twitching, pulling, pushing, etc.
The problem is that special needs are - by definition - special. You do not have to work in this field long before you encounter a client whose needs can not be met by an existing product.
The foil switch allows for rapid customization of switch access. It allows for prototyping abilities not found in commercial products. The therapist can quickly (in the field) evaluate many different sites for switch access and experiment with various ranges of motion. It also means that a therapist can make a switch custom-tailored to an individual. The user can become the switch.
The foil switch activates with an extremely light touch, which is great for clients with low muscle tone. It is also very cheap to make - it costs about $1 for a switch (some commercial switches cost hundreds, but most are under $100 USD). It follows a "make once, use many" approach - once the wiring harness is made, it can be reused again and again and be instantly customized by changing the shape of the aluminum foil.
Over the years, it has proven itself to be an extremely versatile tool and we have used it with many clients, both adults and children.
Step 1: History
We developed this switch when working with a little boy who had Spinal Muscular Atrophy (SMA). The only movement he could make was moving one finger about 3-5 mm. He had practically no muscle tone at all. He normally laid on his side and used a ventilator to help him breathe. We tried all the commercial switches we had (a sizable amount), but he couldn't use any of them. The membrane switches (very light pressure required) were unusable because he couldn't generate enough pressure to use them. Some of the other switches, such as the beam breakers, worked but hampered his breathing because they rested on his ribcage (he had no intercostal muscle control), so they couldn't be used because of the difficulty in mounting them and the interference with his breathing. He was able to use the aluminum foil switch easily to turn toys on and off. It was fantastically light, activated with bare amounts of pressure, molded its shape to his chest, did not impair breathing, and succeeded where $600 switches had failed in the previous evaluation.