  In the framework of the IMEGIN Large Program, we used the NIKA2 camera on the
IRAM 30-m telescope to observe the edge-on galaxy NGC 891 at 1.15 mm and 2 mm
and at a FWHM of 11.1" and 17.6", respectively. Multiwavelength data enriched
with the new NIKA2 observations fitted by the HerBIE SED code (coupled with the
THEMIS dust model) were used to constrain the physical properties of the ISM.
Emission originating from the diffuse dust disk is detected at all wavelengths
from mid-IR to mm, while mid-IR observations reveal warm dust emission from
compact HII regions. Indications of mm excess emission have also been found in
the outer parts of the galactic disk. Furthermore, our SED fitting analysis
constrained the mass fraction of the small (< 15 Angstrom) dust grains. We
found that small grains constitute 9.5% of the total dust mass in the galactic
plane, but this fraction increases up to ~ 20% at large distances (|z| > 3 kpc)
from the galactic plane.
