An incubation system for gas detection of a biological specimen can include a gas or optical sensor. The sensor can be arranged to be placed in communication with at least one biological specimen vessel for generating an electrical response signal indicating a chemical characteristic associated with the specimen. The specimen can be incubated in a temperature-controlled chamber, such as within a shelf defining a plurality of receptacles. Processing circuitry can be included or used such as to place the sensor and at least one biological specimen vessel in communication with each other.