A micro-Pirani vacuum gauge based on micro-hotplate technology

This paper presents a Pirani vacuum gauge based on a micro-hotplate (MHP) supported by six unequal beams. The MHP is fabricated using surface silicon micromachining technique. A thermal model for the gauge is established by means of Fourier analysis, which takes account of internal heat source in the beams and pressure-dependent gaseous heat conduction above and below the MHP. It is applied to determine the MHP operation temperature, temperature distributions along the supporting beams and heat losses through various mechanisms at different vacuum pressure. The measurements of gauge characteristics have been done and the results show good agreements with theoretical analysis. The measured sensitive range of the gauge is 10−1 to 105 Pa when driven by a constant current, 0.8 mA.