Development and Mass Production of the HSPPA Series Piezoresistive Type Waterproof MEMS Pressure Sensor (to Detect Absolute Pressure)

Applications for pressure sensors are continuing to expand into a wide array of fields, including medical and industrial devices; pressure sensors are used in the automotive field in particular to detect oil pressure in brakes and power steering as well as combustion control in engines. The growing use of pressure sensors has extended to such consumer devices as washing machines in recent years, while mounting them onto such familiar compact digital devices as digital cameras and wrist watches is no longer unusual.



Applications for pressure sensors designed for compact digital devices include wrist watches for outdoor use and divers wrist watches, which measure barometric and water pressure, respectively. They also include digital cameras and digital camcorders that can perform such functions as color-correction and water depth detection during underwater photography.



Through the use of propriety thin-film process, microfabrication and package technologies cultivated over many years, ALPS has developed the world’s smallest piezoresistive/waterproof-type pressure sensor, realizing a design that is compact and short (Diameter: 3.95mm x Height: 1.85mm).



The sensor detects pressure by reading the electrical signals that result from changes in electrical resistance generated when external pressure causes the diaphragm to flex, which then distorts the piezoresistive element formed above the diaphragm. Utilizing direct detection of the electrical resistance of the piezoresistive element through the diaphragm’s flexible volume enables a simple element structure, making this type of sensor suitable for compact-sized components.



Owing to the optimal use of structures and materials designed to realize waterproof capability, the HSPPA series maintains a high degree of water resistance, while achieving a highly sensitive level of performance as a pressure detector.



In addition, this product features minimal fluctuation characteristics due to the stable cavity*2) configuration resulting from etching optimization and Si-Si sealed joints*3 that control the impact of external component stress.



In addition to waterproof-type pressure sensors, ALPS also features regular-type MEMS pressure sensors (single element- and built-in amplifier-type sensors) in its lineup of products.