Micro capacitive pressure sensors have important application value in fields such as biomedicine, drone positioning, and wearable devices. This study focuses on MEMS capacitive gauge pressure sensors. A high-precision capacitive pressure sensor is designed and fabricated for implantable biomedical applications. This device is formed by anodic bonding between a glass substrate with fixed electrodes and an SOI wafer with elastic membranes. The elastic membrane will deform when the pressure on both sides changes, resulting in a change in the capacitance of the device. The readout circuit calculates the external pressure by detecting changes in capacitance. This paper improved the nonlinearity of capacitive pressure sensors by designing a structure of a boss on the membrane. The result from ANSYS finite element simulation shows that the nonlinearity was improved from about 17% (flat membrane) to 7% (with boss structure). The structure of the boss was formed by anisotropic etching of silicon with TMAH, and the SOI buried oxide layer serves as the stop layer of etching to achieve high device consistency. Finally, a packaging and testing platform is built for capacitive pressure sensors and calibration. In the measurement range of 0 ~ 40kPa relative to atmospheric pressure, this device achieved a testing accuracy of 0.30%, nonlinearity of 8%, and repeatability error as low as 0.09%.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |