Dye-sensitized solar cells (DSSCs) have received great attention over the past decade for their high energy conversion efficiency, relatively easy fabrication process and low production cost. However, at present, some practical difficulties such as solvent evaporation, leakage of liquid electrolyte and sealing stability remain serious obstacles to their convenient application.An innovative microfluidic DSSC housing system is here proposed. Sealing performances of such architecture were examined by dynamic fluidic tests and good sealing for pressure up to 50 kPa and temperature of 80 degrees C was obtained, avoiding leakages and bubble formation.Current-voltage and impedance spectroscopy measurements were used to determine the photovoltaic performance of the cell. Results were compared to the ones obtained with DSSC prototypes assembled in our laboratory following a standard procedure, and higher efficiency values have been obtained. (C) 2011 Elsevier B.V. All rights reserved.

In this work, time dependent thermal analyses, performed on the 3D FE model of a multilevel Lab on Chip (LOC) platform are executed in order to gain insight into the temperature distribution within the device. By means of the Comsol Multiphysics CAD import module, an extremely close 3D reproduction of the actual device, allowing to probe temperatures in those regions where an experimental measurement appears difficult or even impossible, is obtained. Different microfluidic chip materials (silicon/Pyrex®, polycarbonate, polymethylmethacrylate and cyclo-olefin copolymer) are virtually tested. Furthermore the close connection between the FE model and the actual device provides an immediate outcome on its fabrication steps.

Cantilever vibration in fluid environment is probably one of the most common Fluid Structure Interaction (FSI) problems in the field of Micro/Nano Electro Mechanical Systems (MEMS/NEMS). Usually the effect of fluid on cantilever oscillation is characterized in terms of mode resonance frequencies and quality factors (Qs), being those two physical quantities what is actually measured in the dynamic operation. In this work a new approach to the above FSI problem is proposed: modes Q factors and resonance frequencies in a viscous fluid environment are calculated through an eigenfrequency analysis thus avoiding time domain simulation as in all the previous works about a computational approach to the current problem. Besides a considerable reduction of the computational time, because of the frequency domain approach, our model demonstrates very high accuracy with respect both to analytical and experimental results.

Silicon resonant microcantilevers for the measurement of the absolute pressure have been fabricated through micromachining processes. The first release is based on vertical resonant actuation and detection, both externally implemented, respectively through a piezoelectric actuator and an optical lever. The variation in resonance response was investigated as a function of pressure (10−1 ÷ 105 Pa), both in terms of resonance frequency and quality factor. We demonstrated the feasibility of a miniaturized absolute pressure sensor working over a six decades range. The second release is based on lateral resonating microcantilevers in which a significative upgrade is represented by the miniaturization and integration of the actuator and the sensing directly on chip providing a more compact and potentially interesting solution for industrial vacuum applications. Actuation is performed with an electrostatic modulated force, while detection relies on a capacitive readout. Preliminary experiments are encouraging for the replication of the results obtained with the first version.

One of the most crucial issues in the domain of microfluidics is the chip to world interface. This paper describes a characterization methodology of a quite common microfluidic interconnection scheme, based on polydimethylsiloxane (PDMS), applied to some of the most popular substrates (silicon, Pyrex and cyclic olefin copolymer) for microfluidic applications. Particular emphasis is given to the evaluation of leakage endurance as a function of the main geometrical parameters of the interconnections and the selected bonding technique. Oxygen plasma activation of the PDMS surface and the application of a thin PDMS interlayer demonstrated the most attractive solutions, due to the straightforward approach and limited cost. Maximum sustainable pressures in excess of 200 kPa have been achieved. Results obtained are critically discussed with the aim to outline PDMS interconnection guidelines for different microfluidic applications.

In this work a detection module for the single nucleotide polymorphisms (SNPs) detection was realised. In particular arrayed primer extension (APEX) was selected as innovative method for SNPs detection and this protocol was scaled down following a micro total analysis approach in order to fabricate a lab-on-a-chip (LOC). Finite element analysis and behavioural simulations with commercial tools to properly design the microfluidic circuitry have preceded the technological processes for the production of the device. The fluidic was designed to contain 5 mu l of DNA and reagents that are inserted through three inlets. The layout includes two mixers and a sealed reaction chamber. Glass/silicon prototypes were fabricated with the employment of micro-electro-mechanical-system (MEMS) processes. The devices were tested with APEX biological protocols customized for the scaled volumes. Furthermore, in order to demonstrate the absence of any negative interaction between the chip and the APEX reagents, different chips were tested in intermediate steps together with the protocol executed in standard conditions. The final result demonstrates that the thermo sequenase extended the probes with the dideoxynucleotides modified with Cy5 fluorophore, thus indicating the possibility of implementation of the APEX protocol on LOC devices. (C) 2007 Elsevier B.V. All rights reserved.

This work is focused on the design, fabrication, and characterization of silicon laterally resonant microcantilevers for measuring absolute pressure. The authors have demonstrated the integration of resonance electrostatic actuation and capacitive readout with a microstructure based on a couple of electrodes and an external amplifier. The microcantilevers have been fabricated with a standard silicon on insulator micromachining process. The characterization method is based on measuring the current at the third harmonic of the excitation frequency flowing through the time-varying cantilever-based capacitor. The variation in resonance response of microcantilevers has been investigated as a function of pressure (10−2−105 Pa), both in terms of resonance frequency and quality factor. Theoretical models and experimental data show very good agreement. The microstructure behavior demonstrates the feasibility of an absolute pressure sensor working over a six-decade range with integrated electrical actuation and readout.

This work is focused on the developing of silicon resonant microcantilevers for the measurement of the absolute pressure. The microcantilevers have been fabricated with a two-mask bulk micromachining process. The variation in resonance response of microcantilevers was investigated as a function of pressure (10−1–105Pa), both in terms of resonance frequency and quality factor. A theoretical description of the resonating microstructure is given according to different molecular and viscous regimes. Also a brief discussion on the different quality factors contributions is presented. Theoretical and experimental data show a very satisfying agreement. The microstructure behavior demonstrates a certain sensitivity over a six decade range and the potential evolution of an absolute pressure sensor working in the same range.