A bourdon tube pressure sensor often uses an LVDT to sense position relative to the applied pressure.

• A. Bourdon tube
• B. Diaphragm
• C. Piezoresistive
• D. Capacitive

Answer: (A)

Measuring pressure with a bourdon tube relies on turning pressure into a detectable linear motion. The curved tube tends to straighten as internal pressure rises, producing a defined displacement at the tube’s end. An LVDT is a precise displacement sensor that converts that linear motion into an electrical signal with high resolution and stability, making it a natural pair for this mechanism. The LVDT’s non-contact, proportional output is well suited to track the tube’s movement as pressure changes, giving an accurate pressure reading.

Other sensing approaches—diaphragms with strain gauges or capacitive elements, or piezoresistive sensors—use changes in material resistance or plate capacitance to infer pressure, rather than directly measuring the larger, more predictable movement of a bourdon tube. While those methods exist, the described setup specifically matches the bourdon-tube mechanism with an LVDT, which is why this option is the best fit.