Heschen M30 Inductieve Nabijheidssensor Schakelaar Schild Type LJ30A3-10-Z/BX Detector 10mm 10-30VDC 200mA NPN Normaal Open (NO) 3 Draad

This proximity sensor worked well and distinguished metals from other conductors such as my finger.I hooked the blue and brown wires up to 12V and got signal out on the black wire. Every time I brought something metal against the sensor it turned on. Nothing happened when I touched it with my finger.The contact surface is large so you would not have to be very accurate. It senses metals a few mm away, and the sensing area seems to be in the middle. It mounts in a hole about 260cm in diameter (you would want to measure this more accurately) using the supplied nut on the back.This sensor seems sturdy, and the blue surface was relatively smooth so it wouldn't be likely to get dirty quickly.

While most of the dimensions are accurate this is not an inductive sensor. Unless my blood contains "adamantium" this sensor will detect any object. It works with as little as 5VDC. Other than the description flaw (capacitive) this appears to be a good product.Cheers