You cannot re-use the chilli sensors from FoodSense, because the capsaicin builds up on the carbon surface during the test. So if you take the same sample and test it three times in a row on the same sensor you will see that the signal increases each time, this is because each time the sensor is used it causes a further build up of capsaicin.

After each test please dispose of the sensor so that it is not accidentally re-used and gives a false high reading on a  subsequent sample.