They activate airbags. Keep aircraft correctly positioned in flight. Detect earthquakes or sudden vibrations in failing machinery. Guide military hardware. Monitor falls in elderly individuals and initiate calls for help. They rotate the display on a smartphone from vertical to horizontal, and measure our exercise intensity and activity level in gadgets we carry or wear.

These and hundreds of similar tasks are performed around the world every day by accelerometers—sensors that respond to change in motion. They are fast becoming ubiquitous, and their components have shrunk to the micrometer scale. Increasingly, they measure acceleration along three orthogonal axes.

However, despite the growing importance of three-axis accelerometers, there are no standardized testing protocols for evaluating the performance of these microelectromechanical systems (MEMS).

Figure 1: The goniometer-based instrument. The pivot arm is shown with a three-axes accelerometer mounted. Credit: NIST/PML.

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