Microfabricated shear stress sensors, Part 1: Design and fabrication

The design and fabrication of shear stress sensors based on the floating-element method and polysilicon-surface-micromachining technology is reported. Three designs have been developed for microfabrication, two including monolithic integration of mechanical sensor elements with on-chip circuitry. The first design is a four-mask standard polysilicon-surface-micromachining process to develop passive floating-element sensors with optically determined deflection sensitivity. The second-generation devices are fabricated in a six-mask modified N-channel metal-oxide-semiconductor process, where sensor elements and signal conditioning circuitry have been integrated on the sensor die for amplified voltage output. The third design modifies the commercially available micromachined by replacing the accelerometer element with a shear-stress-sensitive floating element, enabling active sensing for Linear response and self-test features.