A force-measuring device (FMD) assembly for a portable electronic apparatus includes a mid-frame including a base portion, a sidewall portion, and a transition region between the base portion and the sidewall portion, and force-measuring devices coupled to the inner surface of the sidewall portion. The sidewall portion and the transition region are elongate along a longitudinal axis. FMDs are coupled to the inner surface at respective contact regions of the sidewall portion and are separated from each other along the longitudinal axis. Each of the FMDs includes strain-sensing element(s). Each of the FMDs corresponds to a respective sense region of the sidewall portion. The transition region includes a respective elongate slit or trough for each of the sense regions. The respective elongate slit or trough is elongate along the longitudinal axis. Adjacent elongate slits or troughs are separated by a respective rib.