Bioreporters refer to intact living cells that have been genetically engineered to produce a measureable signal transcriptionally induced in response to a speciﬁc chemical or physical agent in their environment. Bioreporters contain three essential genetic elements: a promoter sequence, a regulatory gene, and a reporter gene. In the wild-type cell, the promoter gene is transcribed upon exposure to an inducing agent, leading to subsequent transcription of downstream genes that encode for proteins that aid the cell in either adapting to or combating the agent to which it has been exposed. In the bioreporter, the downstream genes, or portions thereof, have been removed and replaced with a reporter gene. Consequently transcription of the promoter gene activates the reporter gene, reporter proteins are produced, and some type of measurable signal is generated. These signals can be categorised as either colorimetric, ﬂuorescent, luminescent, chemiluminescent, electrochemical or amperometric. Although each functions differently, their end product always remains the same: a measurable signal that is, ideally, proportional to the concentration of the speciﬁc chemical or physical agent to which they have been exposed.