Direct creation of micro-domains with positive and negative surface   potential on hydroxyapatite coatings
  A method for the direct patterning of electrostatic potential at the surface of hydroxyapatite is presented here. Micro-domains of surface potential have been created on hydroxyapatite coatings by a 20 keV focused electron beam with minimal alterations of surface chemistry. The success of such approach has been confirmed by Kelvin Probe Force Microscopy measurements, which show that this method is capable of creating micron sized positive and negative local electrostatic potential. The shape and potential difference of these domains were found to depend on the dose of total injected charge from the electron beam as well as the speed with which such charge is injected. 
T. Plecenik, S. A. M. Tofail, M. Gregor, M. Zahoran, M. Truchly, F.   Laffir, T. Roch, P. Durina, M. Vargova, G. Plesch, P. ...
cond-mat.mtrl-sci physics.bio-ph physics.med-ph