How to Select a Strain Gage – What Is The Right Resistance To Use?

DOES STRAIN GAGE RESISTANCE MATTER?

With foil strain gages available with starting resistances from 60 Ω to 20000 Ω, does it really matter which value you choose? Well, like many choices in life, your resistance selection will involve trade-offs. Let's say you choose a higher strain gage resistance. On the plus side, it will provide lower current for equal bridge voltage, which results in less grid self-heating and potentially better resistance stability over time. In addition, there will be higher bridge output when bridge excitation is increased and the lead-wire resistance will have less influence.

The Micro-Measurements Advanced Sensors Technology product portfolio includes linear, shear, bi-axial and diaphragm (circular and linear pattern) gages, arranged as individual, half-bridge and full-bridge configurations, in resistance values up to 20 kΩ, with added flexibility in mounting options. These gages are a preferred choice when low power consumption is crucial, as in battery-powered devices such as electronic torque wrenches, pocket (jewelry) scales, and bicycle and motorcycle sensing and testing equipment; and for applications such as wireless telemetry on rotating components. In addition, higher bridge resistance allows for increased bridge excitation producing more output signal without the destabilizing effects of self-heating. The higher output without additional amplification improves its signal to noise ratio (SNR).