Force-distance Christmas TPU Copper Phosphide molecular_self_assembly ForceDistanceSpectroscopy Writing LFM Tin disulfide P3HT PhaseChange Electrode Sadowski ForceVolumeImage high_resolution PtfeMembrane DOE HighAcpectRatio strontiu_titanate ring shape Nanostructure UnivMaryland kelvin probe force microscopy dichalcogenide SPMLabs Bacteria SmallScan thermal_property ScanningSpreadingResistanceMicroscopy SrO MagneticForce Sidewall HexagonalBN thermal_conductivity