I have a blind and deaf cockerspaniel and I want to wake up at night when he needs to go out. Can anyone recommend a motion detector or an alert system that works for them. I want to hear an alarm of some type so I can wait up and take him out.

Maybe this or something similar:
Amazon.com: Contech StayAway Motion-Activated Pet Deterrent: Pet Supplies

Radio Shack may have an alarm that would work also.

Harbor Freight has a driveway alert. I use it to tell me when deer are passing on the trail. Works great. <$20

What exactly are your needs?

How sensitive to his movements do want an alarm to be?

What type of area do you want to cover? A room, if he crosses a certain doorway...?

Here's the problem I forsee. Any alarm in your house that goes off with movement, very well could go off if he merely rolls over, or scratches himself. You'd be waking up a lot at night.

How old is your dog? Has he ever been crate trained? A crate may be the better option. He'll whine to get out, and if you place the crate in your room, you should hear him whining to alert you.

You can get pressure sensitive pads that go off when the dog gets up, we use these at work on the hospital beds to alert people when a high risk resident tries to get up. Downfall is if the dog just wants to get up for a drink of water in the middle of the night it will also make it go off.

I agree with crating in your bedroom, I do this when training young puppies, the movement in the crate right next to me wakes me up and I know to let them out.