I want to build a proximity sensor that will detect if an object is within 100 cm of the sensor and then send a signal to a raspberry pi. What type of short range detection device should I use to build me sensor? I don't need to know the distance, just if the object is there or not. I have found many different types with a wide range in prices. I want the parts to be low cost.I have been looking at the MuRata Proximity Sensor Pyro-Infrared Sensor, but the range doesn't appear to be enough. Any resources and/or part recommendations would also help.
IMO Infrared Sensor are the most cost effective and currently most commonly used promiximity sensing technology used for detecting a object.
Also take a look at ultrasonic sensors. TDC1000 from Texas Instrument in combination with a piezo ceramic transducer is one that I am fairly familiar.
Time of Flight (TOF) methodology can be used with Ultrasonic and IR techolgy.
Another common technology is Capacitive Proximity Sensors.
Depending on object you are trying to detect Hall Effect Sensors might work as long as object your trying to detect can be embedded with a magnet.
Take a look at Proximity sensor
Usually the simplest system is to place a mirror on opposite end and then shoot lightbeam to the mirror then use a light sensor to see if the beam reaches back or not. This can be a infrared or a visible light beam and is called a photoelectric sensor. This type of sensor has the beneffit of working even in badly lit conditions.
Another way to do this is to use a motion sensor, that is in essence a very low resolution camera that senses change in color. This can also work in infrared range and use its own lightsource so it will work regardless of surrounding light conditions. The benefit of a motion sensor is that you can make the detection area quite large.
You can use ultrasonic sensor. It has range of about 3 meters and is cheap also.