non_contact AtomicSteps polymeric_arrays membrane cross section kelvin probe force microscopy CarbonNanotube ring shape AlkaneFilm Plug LFM Croatia Sperm HighAspect Pattern PvdfBead Barium_titanate CuParticle MagneticPhase BFO Device flakes ContactModeDots HDD multi_layer SPMLabs PhthalocyaninePraseodymium Force-distance temp_control Austenite ElectroChemical pinpoint mode Hysteresys organic_polymer OrganicSemiconductor