Led, accelrometer, proximity sensor project

Hi,
I'm starting on a project, a small device for the elderly.

It comprises of the following:
- Battery
- 2 Led
- Buzzer
- ACCELROMETER ( To guage movement of person)
- PROXIMITY SENSOR (To guage if somthing come near around 1.6M)
- Microprosessor

Design attached

My questions are:
1) To guage movement/no movement what is the best way, ACCELROMETER?
2) Whats is the best sensor type PROXIMITY? 1.6M, moving
3) What else do I need?
4) Can someone help share what is the best electronics to to fit this project from **broken link removed**

Thanks for the help
JAmes

My choice would be an ultrasonic car-reversing-aid type proximity sensor. Accelerometer modules are readily available, but do you really need an accelerometer? If you only want to detect presence/absence of movement couldn't you just sense changes in the output of the proximity sensor?.
What programming skills/facilities do you have?

Thanks Alec,
Point noted on the proximity sensor.

As for the accelerometer, if place on a wheel chair and its not moving for 30sec if will auto off, i'm scared if there is a false trigger when someone walks pass. What kind of sensors allow me to detect inactivity on a wheel chair.

As for programming, i got the full nine yards, located in a education insitute.

Cheers
JAmes

For a wheelchair you could detect motion of the wheels by using a detector maybe a hall effect device on the spokes, and you can detect the presence of a person in the chair by a limit switch on the seat.

....or instead of the Hall effect sensor an optical sensor could sense spoke movement.

You can get cycle computers on ebay for very cheap these days, a couple of quid, one of these gives you a spoke mounted magnet and a frame mounted reed switch.