A new diamond biosensor with integrated graphitic microchannels for detecting quantal exocytic events from chromaffin cells

The quantal release of catecholamines from neuroendocrine cells is a key mechanism which has been investigated with a broad range of materials and devices, among which carbon-based materials such as carbon fibers, diamond-like carbon, carbon nanotubes and nanocrystalline diamond. In the present work we demonstrate that a MeV-ion-microbeam lithographic technique can be successfully employed for the fabrication of an all-carbon miniaturized cellular bio-sensor based on graphitic micro-channels embedded in a single-crystal diamond matrix. The device was functionally characterized for the in vitro recording of quantal exocytic events from single chromaffin cells, with high sensitivity and signal-to-noise ratio, opening promising perspectives for the realization of monolithic all-carbon cellular biosensors

An analytical model for the mechanical deformation of locally graphitized diamond

We propose an analytical model to describe the mechanical deformation of single-crystal diamond following the local sub-superficial graphitization obtained by laser beams or MeV ion microbeam implantation. In this case, a local mass-density variation is generated at specific depths within the irradiated micrometric regions, which in turn leads to swelling effects and the development of corresponding mechanical stresses. Our model describes the constrained expansion of the locally damaged material and correctly predicts the surface deformation, as verified by comparing analytical results with experimental profilometry data and Finite Element simulations. The model can be adopted to easily evaluate the stress and strain fields in locally graphitized diamond in the design of microfabrication processes involving the use of focused ion/laser beams, for example to predict the potential formation of cracks, or to evaluate the influence of stress on the properties of opto mechanical devices.Comment: 29 pages, 7 figure

4H-SiC Schottky diode radiation hardness assessment by IBIC microscopy

We report findings on the Ion Beam Induced Charge (IBIC) characterization of a 4H-SiC Schottky barrier diode (SBD), in terms of the modification of the Charge Collection Efficiency (CCE) distribution induced by 20 MeV C ions irradiations with fluences ranging from 20 to 200 ions/um2. The lateral IBIC microscopy with 4 MeV protons over the SBD cross section, carried out on the pristine diode evidenced the widening of the depletion layer extension as function of the applied bias and allowed the measurement of the minority carrier diffusion lengths. After the irradiation with C ions, lateral IBIC showed a significant modification of the CCE distribution, with a progressive shrinkage of the depletion layer as the fluence of the damaging C ions increases. A simple electrostatic model ruled out that the shrinkage is due to the implanted charge and ascribed the perturbation of the electrostatic landscape to radiation-induced defects with positive charge state

Application of Optimization Procedure to the Management of Renewable Based Household Heating & Cooling Systems

Abstract Renewable heating and cooling systems are cited in the European policy as one of the major means for the decarbonisation of the energy sector. At the household level the main source of renewable energy is represented by solar energy. This energy can be collected and used in the electric or thermal form and more than often its efficient exploitation requires the use of storage facilities. Starting from the previous statements a household heating and cooling system can contain several components whose control and coordination is not easy to handle due to the load variations through the year and during the day, to the weather conditions etc. Simulation and optimization of the energy structure is very helpful in this task because it can provide a commitment of the power flows that ensures the minimal system operational cost together with the satisfaction of load requirements. An optimization procedure based on mixed integer linear programming has been developed and applied to evaluate several household configurations for a location in Northern Italy. Obtained results are compared and assessed in terms of economical saving in system running and of share of renewable energy