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21 ST/Industrial Sensing Solutions Numerous applications may get developed from when an accelerometer and a gyroscope are used together as an IMU with an optional magnetometer. The illustrations highlight some key roles a MEMS iNEMO™ may play in ap- plications and some of more popular iNEMO™ applications, respectively (Figures 5 and 6). Multiple IMUs may get mounted on arms and legs for body tracking and monitoring. Other applications include air mouse (or air pointer), motion gaming platforms, and indoor positioning in an industrial environment. Pressure Sensor Pressure sensors discussed here are absolute pressure sensors that take advantage of the piezoresistivity effect of silicon. Piezoresistivity is a change in the electrical resistivity of a metal or semiconductor due to applied stress (force, pressure, flow, acceleration). The sensing structure of a piezoresistive pressure sensor consists of a membrane with four resistors that get connected in a Wheatstone bridge configuration. The pressure applied to the membrane causes changes in the dimensions of the resistors and modifies their resistance leading to a change in the output of the bridge. STMicroelectronics (ST) has developed an innovative full-Silicon Technology (VENSENS™ technology) for pres- sure sensors (Figure 7). This technology finds its basis in a monolithic sensor that eliminates the need for wafer-to-wa- fer bonding that is used in conventional pressure sensor technology to create the cavity. VENSENS™ technology offers some additional advantages over the other pressure sensor technologies including high burst pressure due to intrinsic mechanical stopper, high shock survivability, more robustness, thinner sensor die, and excellent temperature stability over the full-scale pressure range. There is only one temperature coefficient because only one material (silicon) gets used. Therefore, the temperature increase around the die does not cause any strain in the structure that could cause a shift in the offset of the device. There are numerous applications for a piezoresistive absolute pressure sensor. Some of them are shown in the illustration (Figure 8). Water Level Monitoring / Alarm A pressure sensor can be used to monitor the water level in wash machines, water tanks, etc. The implementa- tion of this application is effortless and straightforward, thanks to embedded capabilities within the device. At the beginning of the washing cycle, with no water in the tub, the reference pressure is measured and stored in an internal register of the device. The next step is to set the threshold in a dedicated internal register according to the water amount needed. When the desired water level gets reached, an interrupt gets generated automatically, and the water flow is stopped via the central control unit. Figure 8: A variety of Pressure Sensor Applications. Figure 6: Some of the significant applications of an iNEMO™ in Consumer, Industrial, and Automotive Markets. Figure 7: Cross-section of Full-Silicon Technology for ST MEMS pressure Sensor.