Abstract: A micro-absorption pump can be used to form microsystems with microdevices such as a mass spectrometer, micro chromatograph, micro crack sensing devices which can be used in microcrack detection of large aeroplane and other structures and chemical or gas sensing lab-on-chip devices, which need evacuation prior to their use. The micro-absorption pump has a chamber containing a cooled absorbent material which is capable of retaining gas molecules on a surface and reducing the pressure of the atmosphere containing the gas molecules. The absorbent is cooled by a liquid, such as liquid nitrogen, or a peltier device and the absorbed gas can be released by heating the absorbent. The micro-absorption pump can be connected to the microdevice to create a low-pressure environment therein.