MEMS accelerometer

A microfabricated proof mass (typically silicon, ~1 μg) suspended by folded-beam springs. Under acceleration, the mass displaces by x = ma/k (Hooke's law + Newton's second law in equilibrium). Displacement is read by capacitive sensing: the mass carries interdigitated comb fingers whose capacitance changes by ΔC ∝ x ∝ a. The device is a physical analog computer that continuously divides force by spring constant — realizing a = F/m at the hardware level without arithmetic. MEMS gyroscopes extend this to Coriolis-effect angular-rate sensing, and IMUs combine three-axis accelerometers and gyroscopes to integrate trajectory in 3D. Found in every smartphone, airbag controller, and inertial navigation unit. Speed: continuous real-time output (bandwidth typically 1 Hz – 10 kHz). Capacity: single scalar (or 3-axis) acceleration; sub-μg resolution in precision variants.