Wheatstone Bridges: Which Has Greater Static Sensitivity?

[tandoorichicken]

Say I have two Wheatstone bridge circuits: On each of them, the top half of the diamond is formed using two fixed resistors. The bottom half of each diamond consists of a variable resistor on the left and a resistance temperature detector on the right. Now, for the first bridge circuit, the two fixed resistors are each 100 ohms, while for the second, they are 25 ohms. Both bridges operate in balanced bridge mode.

Which bridge circuit has the greater static sensitivity?

I know that the bridge is balanced when the ratio of the two top resistors equals the ratio of the two bottom resistors... but this equals 1 in both cases.

My guess is that the lower resistance bridge circuit is more sensitive to changes in voltage, so then it would be the obvious choice. Can anyone confirm this?

 

[FredGarvin]

What is the definition of the static sensitivity? You should end up in units of input to output. So, for instance, if you were measuring pressure, your static sensitivity would be in units of psi/mV or something along those lines.

So in other words, which bridge will create more of a change in output voltage per unit of input?

 

[kyle8921]

I can confirm that your guess is correct. The lower resistance bridge circuit will have a greater static sensitivity compared to the higher resistance one. This is because the lower resistance allows for a larger current to flow through the circuit, resulting in a greater change in voltage when there is a change in resistance. In other words, the lower resistance allows for a larger response to small changes in the resistance temperature detector, making it more sensitive. Additionally, the balanced bridge mode ensures that the sensitivity is optimized for both circuits, but the lower resistance circuit will still have a greater overall sensitivity due to its lower resistance.