Require a motion sensor that can penetrate through perspex/acrylic

[themalloy]

Hi everyone,

I am wanting to find a motion sensor that can penetrate its signal through 3mm of opaque (opal) acrylic/perspex.

The sensor will be placed behind the sheet of acrylic and there will be no sort of receiver on the other end.
The sensor should ideally have an adjustable range.
The range once it passes through the sheet should be between 4 - 10 inches.

I have tried IR, ultrasonic but they all require holes to be cut out of the acrylic for them to work.
PIR sensors have a range that is too big for my needs.

The motion that needs to be detected is that of a persons hand.

Any assistance would be greatly appreciated.

Kind regards,
David

 

[OLIVE2222]

Hi David,

PIR sensor looks to be the better solution to me. What you may try is to reduce is sensitivity should be easier that the other way around.
Capacitive sensor based on pcb's plates can be tried too.

Olivier

 

[davpankhur]

microwave sensors might work for you, they are about $15 and run on 12v or so. they are usually installed in topless cars, so when people leave their cars with the roof open, any hands that goes inside the car will interrupt the microwaves and trigger the alarm or a warning tone.
Im not sure how accurate the range can be set, but i think it is directly proportionate to the power input.

Metal greatly reduces the range, so i assume you could play around with plastics and metal thickness to control the exact distance of detection.