Alessandro Sanginario

Bis-Ferrocene Molecular QCA Wire: Ab Initio Simulations of Fabrication Driven Fault Tolerance

Molecular quantum dot cellular automata (MQCA) are among the most promising emerging technologies for the expected theoretical operating frequencies (THz), the high device densities, and the noncryogenic working temperature. Due to the small size of an MQCA cell, based on one or two molecules, the device prototyping and even a simple circuit fabrication are limited by the lack of control on the technological process. In this paper, we performed an analysis of the possible fabrication defects of a molecular QCA wire built with ad hoc synthesized bis-ferrocene molecules. We evaluated the fault tolerance of a real QCA device and assessed its performance in nonideal conditions due to the fabrication criticalities as we faced in our experiments. We achieved these results by defining a new methodology for the fault analysis in the MQCA technology, based both on ab initio simulations and theoretical computations. The obtained results give quantitative information on the safe operating area (SOA) of a bis-ferrocene molecular wire, and represented an important feedback to improve the technological process for the final experimental set-up.

One-Dimensional ZnO/Gold Junction for Simultaneous and Versatile Multisensing Measurements

The sensing capabilities of zinc oxide nano/micro-structures have been widely investigated and these structures are frequently used in the fabrication of cutting-edge sensors. However, to date, little attention has been paid to the multi-sensing abilities of this material. In this work, we present an efficient multisensor based on a single zinc oxide microwire/gold junction. The device is able to detect in real time three different stimuli, UV-VIS light, temperature and pH variations. This is thanks to three properties of zinc oxide its photoconductive response, pyroelectricity and surface functionalization with amino-propyl groups, respectively. The three stimuli can be detected either simultaneously or in a sequence/random order. A specific mathematical tool was also developed, together with a design of experiments (DoE), to predict the performances of the sensor. Our micro-device allows reliable and versatile real-time measurements of UV-VIS light, temperature and pH variations. Therefore, it shows great potential for use in the field of sensing for living cell cultures.

Carbon Nanotubes as an Effective Opportunity for Cancer Diagnosis and Treatment

Despite the current progresses of modern medicine, the resistance of malignant tumors to present medical treatments points to the necessity of developing new therapeutic approaches. In recent years, numerous studies have focused their attention on the promising use of nanomaterials, like iron oxide nanowires, zinc oxide or mesoporous silica nanoparticles, for cancer and metastasis treatment with the advantage of operating directly at the bio-molecular scale. Among them, carbon nanotubes emerged as valid candidates not only for drug delivery, but also as a valuable tool in cancer imaging and physical ablation. Nevertheless, deep investigations about carbon nanotubes’ potential bio-compatibility and cytotoxicity limits should be also critically addressed. In the present review, after introducing carbon nanotubes and their promising advantages and drawbacks for fighting cancer, we want to focus on the numerous and different ways in which they can assist to reach this goal. Specifically, we report on how they can be used not only for drug delivery purposes, but also as a powerful ally to develop effective contrast agents for tumors’ medical or photodynamic imaging, to perform direct physical ablation of metastasis, as well as gene therapy.

An electronic platform for real-time detection of bovine serum albumin by means of amine-functionalized zinc oxide microwires

We report the fabrication of a customized electronic platform for biosensing, integrating a single functionalized microwire between gold microelectrodes as a sensing element, including a custom microelectronic chip for signal readout. As a proof-of-concept, the platform was validated for the real-time detection of Bovine Serum Albumin (BSA) binding onto an NH2-functionalized zinc oxide (ZnO-NH2) microwire. The ZnO-NH2 microwires were deposited between two gold electrodes by means of a dielectrophoresis (DEP) technique. A Quasi-Digital Impedance Converter (QDIC) was conceived to constantly and instantaneously readout ZnO microwire impedance and transfer data to a laptop. Microelectrodes, a QDIC, a DEP generator, and data analysis were integrated in a stacked-card PCB configuration for a better noise reduction and usability. The system was able to distinguish between different BSA concentrations and to give real-time information about the binding process.

A Low-Power 0.13-

This paper presents a low-power system conceived for the integration and measurement of a nanowire (NW)-based sensor array onto a 130-nm CMOS technology process. Each array element includes a dielectrophoresis (DEP) signal generator for NWs alignment and a quasi-digital read-out circuit (ROC) for impedance conversion. The two subsystems can be digitally controlled by an external microcontroller which reads the ROC output and calculates the resistance and capacitance of the NW. Measurements show that the integrated two-quadrants quasi-digital ROC covers the range 1 MΩ-1Ω G and 100 fF-1 μF with a signal-to-noise ratio ≥44.89 dB. The CMOS system can be considered a building block for the implementation of a complete NW-based sensing array and each element, including both DEP and ROC subsystems, occupies an active area of 0.008 mm2 and only consumes 14.76 μW during read-out phase. The ROC has been also validated using an off-chip nanogapbased nanodevice integrating a single ZnO-NW which has been used as ultraviolet (UV) sensor during experiments. The device has been stimulated by an external UV source providing an irradiance ≥93 μW/cm2 to the nanodevice surface. We have proved that the ROC is able to measure the ZnO-NW electrical characteristics and their variations due to the photogenerated charge carriers.

\mu \text{m}

This paper extends Average Threshold Crossing (ATC) wireless transmission to a multi-channel case by using Address-Event Representation (AER) as the way to convey information. This is encoded in the timings of the transmitted packets which in turn carry the identifier of the event source. By integrating a Impulse RadioUltra Wide Band (IR-UWB) and choosing the proper protocol and modulation, we can aim to minimize the power consumption and provide error detection. The whole system, fully asynchronous, has been implemented in a full-custom chip; besides having multiple independent inputs, it can be configured both to deploy a multi-chip system (with a single receiver) and to optimize wireless transmission parameters. The paper concludes with additional theoretical simulations on the ATC scheme to justify further analyses for our specific application area which regards movement recognition.

CMOS IC for ZnO-Nanowire Assembly and Nanowire-Based UV Sensor Interface

In this paper, we demonstrate that mechanically modified cylinder-shaped carbon nanotube (CNT) working electrodes (WEs), combined with an averaging processing algorithm, can increase electrogenerated chemiluminescence (ECL) limit of detection by more than one order of magnitude, compared to gold electrodes. With CNT WEs, we obtained a stable light emission that lasts for hundreds of voltammetric cycles. This stability was further exploited to increase the detection limit with a simple algorithm, based on mean calculation. Ad hoc fabricated sensors are characterized with a full-custom potentiostat testbed and software platform, using tris(2,2-bipyridyl)ruthenium (II) as ECL labels. Our measurement results show that the signal-to-noise ratio (SNR) improves by a factor of larger than 20 compared to standard gold WEs to reach a detection limit up to 40 pg ?l?1.

A wireless address-event representation system for ATC-based multi-channel force wireless transmission

Low cost CO2 gas sensors for demand-controlled ventilation can lower the energy consumption and increase comfort and hence productivity in office buildings and schools. The photo aoustic principle offers very high sensitivity and selectivity when used for gas trace analysis. Current systems are too expensive and large for in-duct mounting. Here, the design, modeling, fabrication and characterization of two micromachined silicon microphones with piezoresistive readout designed for low cost photo acoustic gas sensors are presented. The microphones have been fabricated using a foundry MPW service. One of the microphones has been fabricated using an additional etching step that allows etching through membranes with large variations in thickness. To increase sensitivity and resolution, a design based on a released membrane suspended by four beams was chosen. The microphones have been characterized for frequencies up to 1 kHz and 100 Hz, respectively. Averaged sensitivities are measured to be 30 µV/(V × Pa) and 400 µV/(V × Pa). The presented microphones offer increased sensitivities compared to similar sensors.

Improving the signal-to-noise ratio of an ECL-based sensor using ad hoc carbon nanotube electrodes

Electronic systems are increasingly fusing multiple technology solutions exchanging information both at electrical and at non-electrical levels, and in general both analog and digital operation coexists in multiple physical domains. This paper introduces a homogeneous multi-domain design methodology which blurs analog and digital boundaries and enables the design of etherogeneous electrical and non-electrical building blocks. The methodology is based on the identification of four fundamental quantities (quadrivium), namely signal-to-noise ratio, signal-to-interference ratio, impedance and consumed energy, applicable to both electrical and multiphysics components. Based on their constraining and their propagation on an ensemble of transactions in time domain, these four elements can be used across different domains (digital or analog), and permit architects to extract internal features, so that these are intrinsically oriented to successive physical and technology-related implementation and modeling. With example application cases, we show that these four quantities in turn define design constraints of electrical and nonelectrical internal units. After presenting an electronic design example, to show applicability in multiple physical domains, the paper discusses and applies the quadrivium also in the context of a MEMS sensor and microfluidic components.

Two clover-shaped piezoresistive silicon microphones for photo acoustic gas sensors

This paper presents a customizable sensing system based on functionalized nanowires (NWs) assembled onto complementary metal oxide semiconductor (CMOS) technology. The Micro-for-Nano (M4N) chip integrates on top of the electronics an array of aluminum microelectrodes covered with gold by means of a customized electroless plating process. The NW assembly process is driven by an array of on-chip dielectrophoresis (DEP) generators, enabling a custom layout of different nanosensors on the same microelectrode array. The electrical properties of each assembled NW are singularly sensed through an in situ CMOS read-out circuit (ROC) that guarantees a low noise and reliable measurement. The M4N chip is directly connected to an external microcontroller for configuration and data processing. The processed data are then redirected to a workstation for real-time data visualization and storage during sensing experiments. As proof of concept, ZnO nanowires have been integrated onto the M4N chip to validate the approach that enables different kind of sensing experiments. The device has been then irradiated by an external UV source with adjustable power to measure the ZnO sensitivity to UV-light exposure. A maximum variation of about 80% of the ZnO-NW resistance has been detected by the M4N system when the assembled 5 μm × 500 nm single ZnO-NW is exposed to an estimated incident radiant UV-light flux in the range of 1 nW–229 nW. The performed experiments prove the efficiency of the platform conceived for exploiting any kind of material that can change its capacitance and/or resistance due to an external stimulus.