Stylus profiler

The morphologies and structures of GO sheets and GO-based membranes were characterized by scanning electron microscope (SEM, Nova NanoSEM 430, 15 kV/10 kV/5 kV), and the thicknesses were measured by Bruker DektakXT Stylus Profiler (Germany). The chemical compositions of membranes were characterized by XPS on ESCALAB250 (150 W, spot size 500 µm) using Al Kα radiation; all spectra were calibrated to the binding energy of adventitious carbon (284.6 eV). XRD patterns were acquired with an XRD diffractometer (D-MAX/2400) using Cu Kα radiation (λ = 0.154 nm). Hydrophilicity of the membrane surfaces was evaluated by a contact angle goniometer. UV–Vis spectra for the dyes were measured on a UV–Vis–NIR spectrophotometer (Varian Carry 5000). AFM (Bruker, Multimode 8) was used to characterize the thickness of GO sheets. FTIR spectra were measured on Bruker Tensor 27 to identify the cross-linking between TA/TH and rGO sheets.

Etching depth of SiNMs was measured by Stylus Profiler (Bruker Dektak XT, Bremen, Germany). The XPS testing of TiO₂ samples was performed on Thermo escalab 250Xi (Thermo Fisher Scientific, Waltham, MA, USA) using monochromatic Al-Ka (1486.6 eV) as the radiation source. The I–V characteristics of Ti/insertion layer (IL)/n-Si metal-insulator-semiconductor (MIS) structures and bendable single crystal silicon TFTs were both measured by using Keithley 1500 semiconductor characterization system (Tektronix, Inc., Beaverton, OR, USA). All the measurements were performed under ambient atmosphere at room temperature without encapsulation.

Stereomicroscope imaging was used to obtain a macroscopic view of the scaffolds (Stereomicroscope Nikon SMZ 745T). The surface roughness of the scaffolds was evaluated by 2D profilometry (Bruker Dektak Stylus Profiler, Billerica, MA, USA). The measurements were carried out on 10 mm lengths of 9 different random struts and were analyzed by Bruker Vision64 software. The stylus tip radius was 2 µm. The 3D surface topography was evaluated using 3D optical profilometry (Zeta 300 3D optical profiler, KLA Instruments, Milpitas, CA, USA). SEM was carried out as explained previously. Microtomography (micro-CT) was carried out to provide information on the scaffold 3D morphology (microCT50, Scanco Medical, Bruettisellen, Switzerland—2 µm voxel size, 45 kV, 133 μA). The surface profile was acquired by a stylus method with a small mechanical contacting force. The lower threshold was set at 40 and the upper threshold was set at 1000 to isolate the PCL scaffold from the background for the evaluation of different morphological parameters.