A system and method for determining a remaining processing capacity of a scrubber having a flow path and a processing material disposed along the flow path. A device may comprise a plurality of optical sensors disposed within the processing material and arranged along the flow path, a light source, and a processor for determining the capacity according to signals received from the optical sensor. The device may be used to illuminate processing material adjacent to each optical sensor using the light source, measure a light value reflected by the processing material at each optical sensor, and determine the remaining processing capacity of the scrubber, using the processor, based on the measured light value. Devices may comprise a memory, such as a non-volatile memory to allow multiple uses of a scrubber without reloading with fresh processing material.
