However, the color detection device (sometimes the human eye) needs to be calibrated against the conductivity method.

There are strict restrictions on their movements and activities and parolees can be monitored by an electronic surveillance detection device.

Other methods relying on instruments include the use of a colorimetric end-tidal carbon dioxide detector, a self-inflating esophageal bulb, or an esophageal detection device.

This produces an infrared image that blends in with its surroundings and confuses enemy detection devices.

However, in the presence of gas and the ensuing ionization, it would be problematic to separate this mode of detection out of the generally operating gaseous detection device.