A metering device for aspirating and dispensing a liquid includes a housing; a pumping medium, preferably a gas containing chamber contained within the housing; a channel having a proximate end in fluid communication with the chamber and a distal end in fluid communication with an external environment; a heat or cold source providing a source of heat or cold to the gas containing chamber; and a temperature sensor for measuring the temperature inside the chamber. In a preferred embodiment, the device further includes a pressure sensor for measuring gas pressure inside the chamber, or multiple chambers. A method for aspirating and dispensing a liquid includes: providing a metering device for aspirating and dispensing a liquid that includes a housing; a gas containing chamber contained within the housing, the chamber; a channel having a proximate end in fluid communication with the chamber and a distal end in fluid communication with an external environment; a heat or cold source providing a source of heat or cold to the gas containing chamber; and a temperature sensor for measuring the temperature inside the chamber; providing a source of liquid to be aspirated; bringing the distal end of the channel into contact with the liquid; cooling the gas containing chamber with the heat or cold source to aspirate a first volume of liquid into the device; and heating the gas containing chamber to dispense a second volume of liquid out of the device. In a preferred embodiment, the metering device is a used in a diagnostic analyzer for determining the presence of one or more analytes in a sample.