Escape Room Puzzle guidance

Projects General Guidance
1

Hi everyone,

I am building escape rooms and I need some guidance specifically on what sensor to use for a puzzle.

The puzzle works like the following:

  1. 8 wooden plates (1/2" thick), each of them has one circular hole on it. 4 of the holes blow air out.
  2. There will be plastic mesh over the hole so that players won't be able to stick their fingers into the hole.
  3. Players need to put their hands over the holes that are blowing air.
  4. The air is generated by a small fan such as a computer fan. The fan is installed behind the wooden plate.

I am not sure what sensors to use to detect if a hand is over a hole.

Notes:

  1. Players won't be able to touch or feel the sensor.
  2. The sensor doesn't have to be in the hole. Since the player is putting the hand over the hole, the hand should also cover some part of the wooden plate.
  3. The room is completely dark.
  4. The sensor should be Arduino friendly.

Ultrasonic sensors could be an option. However, it requires the sensor being exposed to the player. What sensor should I use to detect if a hand is over the hole or the wooden plate?

2

Will the hand over the hole restrict airflow? If so a differential pressure transducer might work.

3

There will be a change in pressure due to the reduced flow - you could measure the flow or the change in pressure ( as per previous )

Google pitot tube, low pressure sensing

4

groundFungus:
Will the hand over the hole restrict airflow? If so a differential pressure traansducer might work.

hammy:
There will be a change in pressure due to the reduced flow - you could measure the flow or the change in pressure ( as per previous )

Google pitot tube, low pressure sensing

Thanks for the advice. I will look into the pressure sensors. The air is generated by a small fan such as a computer fan. The fan is installed behind the wooden plate.

Could barometric sensors work in this circumstances?

5

The output of a barometric sensor will follow the local pressure. If you have 2 sensors, one measuring ambient pressure as a reference and another measuring pressure in the box you could use the difference to see if the flow is restricted.

6

Optical is another option: LDR or other light sensor under the hole, when the hand covers the hole the light is blocked as well.

Will need some calibration as you don't want it to be triggered by shadows or so, only by very high degrees of darkness.

Ultrasound probably won't work as the mesh you put in the hole is likely to reflect the sound waves, as would the edges of the hole and the material around it.