  We experimentally demonstrate a dipolar polariton based electric field
sensor. We tune and optimize the sensitivity of the sensor by varying the
dipole moment of polaritons. We show polariton interactions play an important
role in determining the conditions for optimal electric field sensing, and
achieve a sensitivity of 0.12 V-m$^{-1}$-Hz$^{-0.5}$. Finally we apply the
sensor to illustrate that excitation of polaritons modify the electric field in
a spatial region much larger than the optical excitation spot.
