A capsule adapted to be introduced into the digestive system and gastrointestinal (GI) tract of a mammal including: a capsule shaped container including a capsule wall formed of wall material capable of being bio compatible with the digestive system and being adapted to protect the electronic and sensor devices contained in the capsule; said capsule containing: a micro controller ; a micro heater; a gas spectrometer for detecting gastrointestinal tract gases comprising a semi-conductor gas sensor and a thermal conductive gas sensor each being located with surfaces above the micro heater and being configured, under the control of the micro controller and by changing a temperature of the micro heater, to take readings at two different operating temperature points for a predetermined duration so that they are able to selectively detect one or more of oxygen, hydrogen, carbon dioxide, and methane; a temperature sensor ; a power source ; and a wireless transmission device ; said capsule wall incorporating gas permeable membranes adjacent said gas sensors; and the micro controller being programmed to receive data signals from the sensors and convert the signals into gas composition and concentration data and temperature data suitable for transmission to an external computing device, and being programmed with software to differentiate between oxygen, hydrogen, carbon dioxide, and methane. a capsule shaped container including a capsule wall formed of wall material capable of being bio compatible with the digestive system and being adapted to protect the electronic and sensor devices contained in the capsule; said capsule containing: a micro controller ; a micro heater; a gas spectrometer for detecting gastrointestinal tract gases comprising a semi-conductor gas sensor and a thermal conductive gas sensor each being located with surfaces above the micro heater and being configured, under the control of the micro controller and by changing a temperature of the micro heater, to take readings at two different operating temperature points for a predetermined duration so that they are able to selectively detect one or more of oxygen, hydrogen, carbon dioxide, and methane; a temperature sensor ; a power source ; and a wireless transmission device ; said capsule wall incorporating gas permeable membranes adjacent said gas sensors; and the micro controller being programmed to receive data signals from the sensors and convert the signals into gas composition and concentration data and temperature data suitable for transmission to an external computing device, and being programmed with software to differentiate between oxygen, hydrogen, carbon dioxide, and methane. a micro controller ; a micro heater; a gas spectrometer for detecting gastrointestinal tract gases comprising a semi-conductor gas sensor and a thermal conductive gas sensor each being located with surfaces above the micro heater and being configured, under the control of the micro controller and by changing a temperature of the micro heater, to take readings at two different operating temperature points for a predetermined duration so that they are able to selectively detect one or more of oxygen, hydrogen, carbon dioxide, and methane; a temperature sensor ; a power source ; and a wireless transmission device ; said capsule wall incorporating gas permeable membranes adjacent said gas sensors; and the micro controller being programmed to receive data signals from the sensors and convert the signals into gas composition and concentration data and temperature data suitable for transmission to an external computing device, and being programmed with software to differentiate between oxygen, hydrogen, carbon dioxide, and methane. <EOS>