Since the early 1970s, the electronics industry has been essentially identified with metal-oxide semiconductor (MOS) large-scale integrated circuits. During the past decades, remarkable advances have been accomplished by the downsizing of components (such as MOS field-effect transistors), and the number of transistors on a chip has continuously increased in accordance with Moore's law thanks to constant improvements in lithographic resolution (the top±down approach). However, this approach is unlikely to be sustainable due to intrinsic physical limitations and to the vast increase in production costs. Molecular electronics was proposed in 1974 by Aviram and Ratner [1] as an alternative bottom±up approach for either standard devices (such as diodes and transistors) or new functional devices. It aims to exploit the unique features of molecular systems, such as the high reproducibility and small size of the building blocks, thermodynamically driven self-assembly, and self-recognition. Today, the obstacles to the development of molecular electronics devices appear more technical than conceptual; [2±4] the main problems are the development of reliable methods to interconnect molecules, to characterize and understand their electronic properties, and to exploit them in real devices. In this work, we take advantage of the redox properties and the functional groups of a protein, blue-copper azurin, to achieve a hybrid transistor based on proteins covalently bonded in ordered layers onto Si/SiO 2 substrates. This is a different and innovative approach with respect to those based on physisorbed monolayers obtained by evaporation or spincoating, or based on single nanosized objects like carbon nanotubes that have serious interconnection problems.[5] The integrity of proteins in dry monolayers is investigated by intrinsic fluorescence spectroscopy, and a model for transport due to the novelty of the material is also proposed. Azurin from P. aeruginosa (Fig. 1b, inset) is a 14.6 kDa blue-copper protein that, in vitro, is able to mediate electron transfer (ET) from cytochrome c 551 to nitrite reductase from the same organism.[ ) is located at one end of the b-barrel-structure protein and at a distance of » 2.6 nm from the copper site. [8] It allows the chemisorption of azurin in oriented monolayers onto crystalline gold or other suitably functionalized surfaces. [9,10] Our prototype structure (Fig. 1a) is a planar metal±insula-tor±metal nanojunction, consisting of two Cr/Au (6 nm thick Cr layer under a 35 nm thick Au layer) arrow-shaped metallic electrodes facing each other at the oxide side of a Si/SiO 2 substrate (drain and source electrodes) and connected by the self-assembled protein monolayer.[11] The nanojunction was fabricated by electron-beam lithography, [12] and a silver gate electrode was deposited on the back of the p-doped Si substrate to form an ohmic bond acting as the back gate in a field-effect transistor (FET) configuration. Both the source± drain separation and the oxide thickness were 100 nm. Typically, aft...

Quantum-dot Cellular Automata (QCA) exploit quantum confinement, tunneling and electrostatic interaction for transistorless digital computing. Implementation at the molecular scale requires carefully tailored units which must obey several structural and functional constraints, ranging from the capability to confine charge efficiently on different 'quantum-dot centers'-in order to sharply encode the Boolean states-up to the possibility of having their state blanked out upon application of an external signal. In addition, the molecular units must preserve their geometry in the solid state, to interact electrostatically in a controlled way. Here, we present a novel class of organometallic molecules, 6-3,6-bis(1-ethylferrocen)-9H-carbazol-9-yl-6-hexan-1-thiols, which are engineered to satisfy all such crucial requirements at once, as confirmed by electrochemistry and scanning tunneling microscopy measurements, and first principles density functional calculations.

A major trend in biomedical engineering is the development of reliable, self-contained point-of-care (POC) devices for diagnostics and in-field assays. The new generation of such platforms increasingly addresses the clinical and environmental needs. Moreover, they are becoming more and more integrated with everyday objects, such as smartphones, and their spread among unskilled common people, has the power to improve the quality of life, both in the developed world and in low-resource settings. The future success of these tools will depend on the integration of the relevant key enabling technologies on an industrial scale (microfluidics with microelectronics, highly sensitive detection methods and low-cost materials for easy-to-use tools). Here, recent advances and perspectives will be reviewed across the large spectrum of their applications.

An accurate and easy-to-use Q3 system for on-chip quantitative real-time Polymerase Chain Reaction (qPCR) is hereby demonstrated, and described in detail. The qPCR reactions take place inside a single-use Lab-on-a-Chip with multiple wells, each with 5 to 15 µL capacity. The same chip hosts a printed metal heater coupled with a calibrated sensor, for rapid and accurate temperature control inside the reaction mixture. The rest of the system is non-disposable and encased in a 7 × 14 × 8.5 (height) cm plastic shell weighing 300 g. Included in the non-disposable part is a fluorescence read-out system featuring up to four channels and a self-contained control and data storage system, interfacing with an external user-friendly software suite. Hereby, we illustrate the engineering details of the Q3 system and benchmark it with seamlessly ported testing protocols, showing that Q3 equals the performance of standard commercial systems. Overall, to the best of our knowledge, this is one of the most mature general-purpose systems for on-chip qPCR currently available.

The metalloprotein azurin, used in biomolecular electronics, is investigated with respect to its resilience to high electric fields and ambient conditions, which are crucial reliability issues. Concerning the effect of electric fields, two models of different complexity agree indicating an unexpectedly high robustness. Experiments in device-like conditions confirm that no structural modifications occur, according to fluorescence spectra, even after a 40-min exposure to tens of MV/m. Ageing is then investigated experimentally, at ambient conditions and without field, over several days. Only a small conformational rearrangement is observed in the first tens of hours, followed by an equilibrium state.