Top-view scanning electron microscopy with secondary electrons was performed on a Zeiss LEO 1550-Gemini field-emission microscopes (acceleration voltage: 3-10 kV). Cross-sectional EDXS element mapping and related imaging with back-scattered electrons of the embedded sensors (microtomy block surface) were performed using an environmental FEI Quanta 250 FEG-SEM. The instrument is equipped with an Apollo XL SSD detector for energy-dispersive X-ray spectroscopy and a differential pumping system to allow operation at low-vacuum levels for minimal charging. EDXS element maps were obtained at 5 keV primary electron energy to obtain sufficient count rates at the best achievable lateral resolution under low-vacuum conditions (around 100 Pa).