Microscale Test Equipment

Forces from newtons to millinewtons are commonly measured using strain gauge load cells. Load cells come with a Wheatstone bridge configuration, featuring a mV/V output or with an integrated amplifier providing common process output signals. Upon bending a deflection beam, areas with mechanical strain and compression develop that can be measured with mechanicalelectric transformers, e.g., foil-strain measurement stripes. These metallic stripes have an isolating carrier foil, which is glued to the backside of the beam. The force-dependent changes of the resistance are measured in a Wheatstone bridge, and in an amplifier the changes are transformed to a voltage or current signal for further processing. The use of load cells is limited to forces not smaller than a few millinewtons. If the forces become smaller, the signal-to-noise ratio does not allow a precise measurement.