¹ENEA, Centro della Casaccia

 This work aims to the development of a fabrication technique for miniaturized bioelectronic devices that is fully compatible with the techniques used in conventional solid state microelectronics. The implications of the method span from clinical use biosensors to DNA sequencing to truly molecular electronics.

Our technique is based on laser pulse vaporization of organic and biological molecules in a high vacuum environment and on the subsequent multiple photon ionization of the vapour phase molecules by a second selectively tuned laser pulse The ions produced can then be directed to the deposition substrate by means of electric fields; high resolution patterning can be achieved by tghe insertion of microlithographic masks on the ions trajectory or by localizing the field using thin moveable tips such as those of Scanning Probe Microscopes.

In this work we checked the biological functioning of biomolecules deposited by this method, and we studied the fragmentation of organic molecules after their ionization in vapour phase. We also studied the adhesion of the molecular layers to the substrate and, by means of suitable patterns, we determined thickness (few molecular layers) and uniformity of the layers by AFM microscopy. Depositions have been achieved both through masks, with resolutions of the order of 100 nm, and by electric fields localized on a few microns range; in this latter case we also tried moving the field spatially to pattern the deposition at low resolution. We also tried the deposition of metallic layers by the same technique in order to attempt the fabrication of submicroscopic conductors and electrodes.