Strain gages are resistors, which heat up when current flows through them. Dissipating this heat will allow the gage to remain stable, and respond accurately to strain.due to load or stress.
When a gage is bonded on a material having good heat conducting property, such as aluminium, the gage can withstand a significant amount of current through it without any noticeable self-heating effect , and a strong strain signal can be obtained with higher excitation voltage on the gage.
On materials that are poor heat conductors such as plastic or glass, the excitation voltage applied to the gage needs to be limited to perhaps less than 1 volt, to prevent the gage from heating up and showing a significant error in strain measurement.
But low excitation voltage results in a weak strain signal from the gage. In such a case it is necessary to have a very stable , high gain signal conditioning amplifier to get good strain readings. The straingage instruments from Micro Measurements have the ability to handle such situations extremely well, ensuring reliable and accurate strain measurements.