wonderfuliot:
The device is battery powered and cannot afford to use delay. It is designed to be interrupt driven for this very purpose, it sleeps most of the time.
That was not stated in the Original Post.
Sometimes, for each high to low transition, the sensorTriggered ISR is fired 2 times for no apparent reason.
You should probably clear the interrupt flag immediately before reinstating the interrupt in case one was recorded immediately before the main interrupt had time to detach itself.
...R