Table 1 In-situ approaches¹¹ for biofilm characterization with additional references.

Optical microscopy

Local observation of planar microstructure in an intact biofilm in case of no staining.

^{38, 39}

Confocal laser scanning microscopy (CLSM)

Volumeric microstructure of biofilm can be observed in situ from laser intensity without staining.

^{40,41,42,43,– 44}

Environmental scanning electron microscopy

Observation of local microstructure in near-atmospherical vacuum environment with higher resolution than optical diffraction limit.

^{45, 46}

Raman spectroscopy

Chemical structures in biofilm can be assessed in situ.

^{22, 39, 47}

Fourier transform infraredspectroscopy (FTIR)

The chemical functional groups in biofilm can be analysed macroscopically in situ in case of attenued total reflection technique.

^{33, 34, 47}

Quartz crystal microbalance (QCM)

Time-series biofilm formation can be indirectly detected in situ via frequency changes.

⁴⁸

Wettability

In-situ macroscopic representation of physicochemical information of intact hydrous biofilm.

This study