Principles of Biomedical Systems & Devices Principles of ... - Rowan

Strain gage w/ Wheatstone
Bridge
PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404
υ i
R x
R y
R 2 =A
a
∆υ o
B
C
d
c
R 3 =D
Diaphragm
A
D
R 4 =C
R i
R 1 =B
b
Armature
Strain-gage wires
R
∆V
1
0 = 0 ⇔ =
R
2
Let all R initially be equal to R 0 « R i . If R 1 and R 3
increase and R 2 and R 4 decrease by ∆R, then
∆v
0
=
∆R
R
0
vi
R
R
4
3
R 1
R 4
R 2
R 3