MEMS accelerometer investigation in an undergraduate engineering technology instrumentation laboratory

Accelerometers that are manufactured using micro electro-mechanical system (MEMS) techniques are becoming ubiquitous in many consumer and industrial products. The MEMS process allows for electro-mechanical devices to be produced very inexpensively. Because the MEMS accelerometer package also integrates the signal conditioning electronics, these devices can be implemented quite easily in many designs. For these reasons, it is important that engineering technology students become familiar with the operating principles and characteristics of MEMS accelerometer devices that they will likely encounter in their careers. As part of an undergraduate engineering technology instrumentation course, students at Penn State Berks investigate the characteristics and principles of operation of some low-g accelerometers. One device (±1.5g) is used as a tilt sensor. Such a device is very common in handheld consumer electronic devices to sense its orientation with respect to the earth's horizon. A plethora of applications can be built around this type of spatial orientation information. Familiar examples include display orientation (portrait or landscape) for video devices, and gaming control such as the Nintendo® Wii system. A second device (±40g) is investigated for its applications in vehicle motion measurement. Hands-on experience with these devices yieldssome unusual behavior (in both the students and the devices). This is the students' first encounter with electronic devices that are sensitive to their position on the laboratory bench. Simple apparatus are used to characterize and verify performance of the devices. This paper presents the laboratory apparatus and software as well as examples of assignments and student data analyses.