Both the pyroelectric sensor and non-contact MEMS thermal sensor can detect even the slightest amount of radiant energy from objects such as infrared radiation and convert them into temperature readings. However, unlike pyroelectric sensor that relies on motion detection, non-contact MEMS thermal sensor is able to detect the presence of stationary humans (or objects).
MEMS thermal sensor (thermopile)
Converts temperature readings by “continuously detecting the temperature of radiant energy” in its field of view.
Able to detect both stationary and motion state of humans (objects).
Pyroelectric sensor
Converts temperature readings only when detecting “temperature changes in the radiant energy” in its field of view.
Unable to detect stationary human (object) presence