There is a growing need for multi-axis force torque (F/T) sensors to aid in the assembly of micro-scale devices. Many current generation robotic microassembly systems lack the force-feedback needed to facilitate automating common assembly tasks, such as peg-in-hole insertions. Currently, most microassembly operations use vision systems to align components being assembled. However, it is difficult to view high aspect ratio component assemblies under high magnification due to the resulting limited depth-of-field. In addition, this difficulty is compounded as assembly tolerances approach dimensions resolvable with optics or if the mating parts are delicate. This paper describes the development of a high sensitivity F/T sensor. Optimal design theory was applied to determine the configuration that would result in the most sensitive and accurate sensor: Calibration experiments demonstrated that the sensor can resolve down to 200μN and possibly less.