In a Wheatstone bridge pressure sensor, what describes the electrical signal produced as pressure changes?

In a Wheatstone bridge pressure sensor, what describes the electrical signal produced as pressure changes?

• A. A single-ended voltage output relative to ground.
• B. A differential voltage output resulting from resistance changes in the piezoresistive elements.
• C. A current proportional to pressure with no voltage output.
• D. A temperature-dependent signal unaffected by pressure.

Answer: (B)

The signal is a differential voltage produced by the Wheatstone bridge as the piezoresistive elements change resistance when pressure is applied. In a bridge, pressure strains the resistors so opposite arms shift in resistance in a way that unbalances the bridge. That imbalance shows up as a voltage between the two middle nodes, which is the differential output. This setup is sensitive because the small resistance changes are converted into a voltage difference, and it also helps reject common-mode noise since the useful signal is the difference between the two bridge outputs rather than a voltage referenced to ground. The output is not a current with no voltage, and it’s not independent of pressure—the differential voltage is proportional to the pressure-induced strain (and is typically amplified for measurement). Temperature effects can influence the resistances, but the bridge is designed to provide a pressure-dependent voltage rather than a temperature-only signal.

The signal is a differential voltage produced by the Wheatstone bridge as the piezoresistive elements change resistance when pressure is applied. In a bridge, pressure strains the resistors so opposite arms shift in resistance in a way that unbalances the bridge. That imbalance shows up as a voltage between the two middle nodes, which is the differential output. This setup is sensitive because the small resistance changes are converted into a voltage difference, and it also helps reject common-mode noise since the useful signal is the difference between the two bridge outputs rather than a voltage referenced to ground. The output is not a current with no voltage, and it’s not independent of pressure—the differential voltage is proportional to the pressure-induced strain (and is typically amplified for measurement). Temperature effects can influence the resistances, but the bridge is designed to provide a pressure-dependent voltage rather than a temperature-only signal.