Realization of a micro pressure sensor with high sensitivity and overload by introducing beams and Islands

Presented is a piezoresistive absolute micro pressure sensor for altimetry. This investigation involves the design, fabrication and testing of the sensor. By analyzing the stress distribution of sensitive elements using finite element method (FEM), an improved structure is built up through introducing multi islands and sensitive beams into traditional flat diaphragm. The proposed configuration presents its advantages in terms of enhanced sensitivity and overload resistance compared with the bossed diaphragm and flat diaphragm structures. Multivariate fittings based on ANSYS^® simulation results are performed to establish equations about surface stress and deflection of the sensor. Optimization by MATLAB^® is carried out to determine the structure dimensions. Silicon bulk micromachining technology is utilized to fabricate the sensor prototype, and the fabrication process is discussed. The output signals under both static and dynamic conditions are evaluated and tested. Experimental results demonstrate the sensor features a relatively high sensitivity of 17.795 μV/V/Pa in the operating range of 500 Pa at room temperature and a proper overload resistance of 200 times overpressure to promise its survival under atmosphere. The favorable performances enable the sensor’s application in measuring absolute micro pressure.