They have a high pressure side port and a low pressure side port. If you push air(pressure) into the high side port, contact is made between the 2 terminals. If you suck air(vacuum) on the low side port, contact is made between terminals. 6volt Nimh battery- 2200 maH.
Imagine a piece of tubing in user's mouth connected to a barbed tee, where 1 tube goes to the high port on 1 switch, and 1 tube goes to low port on other switch.
I a very familiar with the concept and I had an idea that it was the purpose, but I think you misinterpret what this sensor will do. The reason for two ports is just that it's a relative pressure switch and blowing into one port has the same effect as a suction at the other end.
The two ports goes into a chamber that's separated by a membrane. blowing into one port will make it deflect away from this pressured port and suction at the other port will make it deflect in the same direction. So, either blowing into one port at the time, or blow and suck the same port, will get the effect you're after - unfortunately this sensor cannot do what you want though as it's unidirectional in its output.
For your purpose, any sensor that have different output for positive and negative pressure in the needed range will work.
The Freescale MPXV7002 is a +/-2kPa sensor with around 2.5V output at zero pressure (lower voltage with negative pressure and v.v.) This would work for a single blow/suck tube and you'd need a bit of electronics between sensor and actuator anyway
I have no idea of how hard your target user can suck and blow, but the 2kPa (~0.3 PSI)
is just the max range and a simple comparator can make it work with eg. a tenth of that if needed.
The linear actuator is energized by reversing polarity. 2 wires coming out of actuator- reverse polarity on those 2 wires to change direction.
OK, You'll need to measure the current it takes, to stop it when a suitable pressure is reached to hold whatever it needs - or you may burn out the windings.
A conventional (rotating) servo would probably be cheaper.
Including a spring may help in holding without crushing.
[...] you are helping paralyzed people gain independence.
No, I'm helping you make money
I really dislike when people try to con me into something with the "for the kids/sick/whatever" Please don't, I've been making stuff for disabled people since I was a pre-teen anyway - dishonesty is just putting me off, if anything.