Pfqne al probe

Energy-dispersive X-ray spectroscopy (EDX) was used to analyze the chemical composition of different sections of the samples. The samples were directly deposited on carbon tape sections fixed on aluminum supports, and no gold coating was applied in order to avoid any interferences between sulfur and gold.
The Atomic Force Microscopy (AFM) images were obtained using a Bruker Dimension Icon microscope. A thin slice of the sample was mounted onto a metallic disc glued with double-sided tape, and, for the electrical measurements, a thin layer of silver paint was used to connect the sample surface to the metallic disc and the microscope stage. Given the fact that Young’s moduli of PEDOT:PSS and PLGA are of the order of a few GPa [43 (link),44 (link)], for the nanomechanical measurements performed using the Quantitative Nanomechanics kit from Bruker, a Bruker RTESPA probe (nominal spring constant, k = 40 N/m, tip radius 8 nm) was selected since it is the one recommended for Young’s modulus ranging from 0.2 to 8.1 GPa. On the other hand, to obtain the surface potential maps by means of Kelvin Probe Force Microscopy (KPFM), a Bruker PFQNE-AL probe was used (k = 0.8 N/m, tip radius 5 nm). In this case, the work function of the tip was measured by using a gold/aluminum calibration sample (Bruker PFKPFM-SMPL) since the work function of gold can be averaged to 5.38 eV [45 ].

In all our studies we used a Bruker Dimension Icon AFM instrument (Bruker Nano Inc., Santa Barbara, CA, USA). The topography scans were collected in PeakForce Tapping mode using a ScanAsyst Air probe (0.4 N/m spring constant, Bruker AFM Probes, Camarillo, CA, USA) with a 0.5–2 nN setpoint. Care was taken to align the scans parallel to the long axis of the sensilla to avoid contaminating the probe with adhesive from the double-sided sticky tape. The surface potential scans were done in PeakForce Kelvin Probe Force Microscopy frequency modulated mode (PF-KPFM-FM) using a PFQNE-AL probe (0.8 N/m spring constant, Bruker AFM Probes, Camarillo, CA, USA) with a 0.5–2 nN setpoint and a 25 nm lift height. The same care was taken to align the scans parallel to the long axis of the sensilla to avoid contaminating the probe with adhesive from the double-sided carbon conductive tabs. All data analysis was performed in Nanoscope Analysis 2.0 (Bruker Nano Inc., Santa Barbara, CA, USA).