  Quantum electrodynamic fluctuations cause an attractive force between
metallic surfaces. At separations where the finite speed of light affects the
interaction, it is called the Casimir force. Thermal motion determines the
fundamental sensitivity limits of its measurement at room temperature, but
several other systematic errors contribute uncertainty as well and become more
significant in air relative to vacuum. Here we discuss the viability of several
measurement techniques in air (force modulation, frequency modulation, and
quasi-static deflection), characterize their sensitivity and accuracy by
identifying several dominant sources of uncertainty, and compare the results to
the fundamental sensitivity limits dictated by thermal motion and to the
uncertainty inherent to calculations of the Casimir force. Finally, we explore
prospects for mitigating the sources of uncertainty to enhance the range and
accuracy of Casimir force measurements.
