Optical methods are the preferred measurement techniques for bio-sensors and lab-on-chip applications. Their key properties are sensitivity, selectivity and robustness. To simplify the systems and their operation, it is desirable to employ label-free optical methods, requiring the functionalization of interfaces. Evanescent electromagnetic waves are probing the optical properties near the interfaces, a few 100 nm deep into the sample fluid. The sensitivity of these measurements can be improved with optical micro-resonators, in particular whispering gallery mode devices. Q factors as high as 2x10(8) have been achieved in practice. The resulting narrow-linewidth resonances and an unexpected thermo-optic effect make it possible to detect single biomolecules using a label-free biosensor principle. Future generations of biosensors and labs-on-chip for point-of-care and high-troughput screening applications will require large numbers of parallel measurement channels, necessitating optical micro-resonators in array format produced very cost-effectively.
This paper discusses the effects of MOSFET threshold voltage variations on the reliability of nanometer-scale CMOS logic gates. The reliability is quantified in terms of the probability-of-failure of individual CMOS gates, which is obtained from extensive Monte Carlo simulations of these gates. The study considers different nano-scale CMOS technology generations and compares the effect of threshold voltage variations on the reliability at the gate level. The results presented here show a clear dependency pattern of reliability on the gate’s input combinations (vectors). The results also show that both the NAND and Majority logic gates can tolerate up to 40% of threshold voltage variations in a 90nm technology, while only up to 20% at the 22nm technology node.
When analyzing reliability, wires have in most cases been ignored, with gates (and devices) taking the lion’s share. With scaling, this “only computing fails” approach is not going to be accurate enough as communication (wires) will also start to err. Trying to do justice to wires, this paper details a statistical failure analysis of wires following on the few papers which have made wires’ reliability their concern. We will use a classical particle-like probabilistic approach to enhance on the accuracy of wires’ length-dependent probabilities of failure due to the discreetness of charge. Covering some of the intrinsic noises, such an approach leads to “lower bound”-like wire reliability estimates, as ignoring other intrinsic noises, as well as extrinsic noises, variations, and defects. These results should have implications for multi-/many-cores and networks-on-chip, as well as forward-looking investigations on emerging nano-architectures.
In this paper we consider possibilities to mimic quantum-like computations with classical nano-scale devices. In particular, we study dynamics of coupled oscillators arrays and propose a method to imitate basic one-qubit and two-qubit operations using coupled oscillator networks.
In this paper we present a review of recent advances in the field of ultra-sensitive imagers with ultra fast detection capability. Photon counting capability in these sensors is generally available, along with time-of-arrival analysis, thus enabling an increasingly broad range of diagnostics applications. The current trend is to migrate the designs with nanometric feature sizes and to push integration to new highs, so as to enable placing more functionality and more processing on pixel and on chip. Examples of these new trends are given in the context of industrial and bio applications.
In this paper our aim is to identify layered hierarchical generic network topologies which could closely mimic brain's connectivity. Recent analyses have compared the brain's connectivity (based both on a cortical-equivalent Rent's rule and on neurological data) with well-known network topologies used in supercomputers and massively parallel computers (using two different interpretations of Rent's rule). These have revealed that none of the well-known computer network topologies by themselves are strong contenders for mimicking the brain's connectivity. That is why in this paper we perform a high-level analysis of two-layer hierarchical generic networks. The range of granularities (i.e., number of gates/cores/neurons) as well as the fan-ins and the particular combinations of the two generic networks which would make such a mimicking achievable are identified and discussed.
The interconnection problem associated with large scale hardware-based neural networks is well known. A time multiplexed neural network architecture using silicon based quantum devices with MOS/CMOS devices is described and shows significant increased functional density compared to conventional devices.
The Suspended Gate Field Effect Transistor (SG-FET) appears to have the potential to replace traditional FETs in sleep mode circuits, due to its abrupt switching enabled by electromechanical instability at a certain threshold voltage and its ultra low “off” current(I off ). This paper presents a preliminary assessment of the SG-FET potential if utilized as sleep transistor in real applications, e.g., microprocessors. We first evaluate various SG-FET instances in terms of switching delay, current capability, and leakage. Subsequently, we compare these figures with the ones offered by traditional switch transistors utilized in CMOS technologies. Our simulation results indicate that SG-FET based sleep mode circuits are potentially interesting as they clearly enable substantial leakage reductions due to their extremely low “off” currents (4 orders of magnitude lower than FET) at the expense of a 4x larger active area for the same capability to drive current.
Nanoelectrochemical immunosensors fabricated by templated electrodeposition of gold nanoelectrodes inside the pores of polycarbonate (PC) track-etched membranes, followed by the immobilization of the biorecognition elements on the surrounding PC, have proven high sensitivity and specificity for protein detection. The signal transduction scheme involves a suitable redox mediator added to the sample solution to shuttle electrons from the gold nanoelectrodes to the biorecognition layer, both elements being in strict spatial proximity. Highly improved signal-to-background current ratio, which are peculiar of NEEs with respect to other electrochemical transducers, can be exploited in this way. Two detection schemes were tested: one based on the direct immobilization of the target protein on the PC of the NEE (approach A) and the other based on the immobilisation on PC of an antibody to capture the target protein (approach B). The biorecognition process was completed by adding a primary antibody and a secondary antibody with horse radish peroxidase (HRP) as enzyme label; methylene blue was the redox mediator added to the electrolyte solution. Typical target analytes were single chain fragment variable proteins, for approach A, and trastuzumab (also known as Herceptin®), for approach B. NEE-based capture sensors were tested successfully to detect small amounts of the receptor protein HER2 in biological samples. Finally, motivated by the target of a better control of the geometrical characteristics of ensembles of nanoelectrodes (size, density, geometrical arrangement, and degree of recession), and by the positive results obtained with track-etch membranes of PC from the standpoint of protein immobilization, we demonstrated the fabrication of nanobiosensors by patterning ordered arrays of nanoelectrodes (NEAs) by electron beam lithography (EBL) on polycarbonate. EBL results perfectly suitable for the top-down fabrication of arrays of nanobiosensors on thin PC films deposited on gold coated silicon.
In this paper, we discuss information transfer through calcium signaling, one form of molecular communication that is ubiquitously used in natural biological systems and that is potentially useful to design synthetic biological systems. We use a mathematical model to describe a molecular communication system in which a transmitter communicates information with the receiver over a calcium signaling channel. Mutual information between transmitter and receiver is then used to calculate the amount of information transfer from the transmitter to the receiver. An example simulation result is provided to illustrate how we measure the amount of information transferred over a calcium signaling channel. Our approach may further develop an understanding of design principles of biological systems as well as help design synthetic biological systems.
In this paper we address the possibility to improve the reliability of small to middle-size circuits without employing redundancy. Circuits’ reliability is improved by reducing the logic depth of critical paths since the probability of failure of each output of the circuit depends no the logic depth of critical paths. Circuits of the same size were considered, as well as different synthesized versions of the same circuit and the estimation of the probability of failure is given with respect to the logic depth.
Nanomaterials have properties that are often very different from normal materials made of the same substance, which can be used to create novel products with exciting properties. However, the health and environmental impact of these nanomaterials is also changed and their potential risk needs to be studied. There is evidence that some nanomaterials can pass through tissue barriers (including the blood-brain barrier) and cell membranes. This is interesting for medical applications, but it raises concerns about the impact of non-medical nanomaterials. Current research aims at better coordinating research efforts and at better communication between researchers and involved stakeholders. Many research labs and production sites currently follow strategies that were established for dealing with very toxic chemicals and powders, until future research in this field helps identify the appropriate level of protection. All these efforts will ultimately ensure a safe, healthy and environmental friendly production, use and disposal of nanomaterials.
Novel medical applications involving embedded sensors, require ultra low energy dissipation with low-to-moderate performance (10kHz-100MHz) driving the conventional MOSFETs into sub-threshold operation regime. In this paper, we present an alternate ultra-low power computing architecture using Binary Decision Diagram based logic circuits implemented using Single Electron Transistors (SETs) operating in the Coulomb blockade regime with very low supply voltages. We evaluate the energy – performance tradeoff metrics of such BDD circuits using time domain Monte Carlo simulations and compare them with the energy-optimized CMOS logic circuits. Simulation results show that the proposed approach achieves better energy-delay characteristics than CMOS realizations.
Recently, the conjugated polymer – inorganic nanocomposites have been increasingly studied due to the potential applications of these advanced materials in developing optoelectronic devices. In this work nanocomposite materials thin films based on poly [2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and nanocrystalline TiO2 (nc-TiO2) have been fabricated. The photoluminescence (PL) spectra of pure MEH-PPV and nanohybrid films have shown that the excitation at a 470 nm wavelength leads to the strong quenching in photoluminescent intensity due to the compositions of TiO2 component. Current-voltage (I-V) characteristics of multi-layer device with structure of Al//MEH-PPV:nc-TiO2//PEDOT:PSS//ITO//glass were investigated. The obtained results suggest the application of the hybrid MEH-PPV:nc-TiO2 materials in polymeric solar cells.
In this contribution we describe the application of Ink-Jet printing and Stencil Lithography in bionanotechnology. Both techniques are alternative patterning methods that can be used for the fabrication of biocompatible micro- and nanostructures out of the costly and restricted clean room environment. The applications presented in this contribution are 1) the cell patterning using Au dot arrays deposited on PDMS,by stencil lithography, 2) the fabrication of biosensors based on localized surface plasmon resonance in Au nanodots deposited by stencil lithography and 3) the printing of cells and biomolecules by InkJet printing.
A new approach for inserting repeaters in 3-D interconnects is proposed. The allocation of repeaters along an interplane interconnect is iteratively determined. The proposed approach is compared with two other techniques based on conventional methods used for 2-D interconnects. Simulation results show that the proposed approach decreases the total wire delay up to 42% as compared to conventional approaches. The complexity of the proposed algorithm is linear to the number of planes that the wire spans.
To understand the temporal dynamics of brain networks, we applied a model based on complex-systems for brain networks, with a new measure of stability that corresponds to the network integrated with multiple oscillators. The simulation demonstrated that elementary coupled network shows high stability measure. This is the first step in our efforts to estimate the temporal dynamics of human brain networks.
3D stacked chips have become a promising integration technology for modern systems. The complexity reached in multi-processor systems has increased the communication delays between processing cores, and an effective way to diminish this impact on communication is the 3D integration technology and the use of through-silicon vias (TSVs) for inter-layer communication. However, 3D chips present important thermal issues due to the presence of processing units with a high power density, which are not homogeneously distributed in the stack. Also, the presence of hot-spots creates thermal gradients that impact negatively on the system reliability and relate with the leakage power consumption. Thus, new approaches for thermal control of 3D chips are in great need. This paper discusses the use of a grid and non-uniform placement of TSVs as an effective mechanism for thermal balancing and control in 3D chips. We have modelled the material layers and TSVs mathematically using a detailed calibration phase based on a real 5-tier 3D chip stack, where several heaters and sensors are manufactured to study the heat diffusion. The obtained results show interesting conclusions and new in- sights in the area of thermal modeling and optimization for 3D chips using TSVs.
A compact platform for producing sub-micrometer 3D interconnects and networks for bacterial carriers and electrical signal transmission is briefly presented. The platform is composed of a dispensing system using polyurethane doped with silver nanoparticles, curing system controlling the polymerization process by emitting UV light, and an annealing system which is used to remove the cured resin and sinter the silver nanoparticles to reach suitable resistivity. We also add a video microscope to help the optimization of the process.
We propose a method for the separation of long DNA molecules, based on elastomeric nanochannels with tunable cross section. These nanoconfinement structures can be used to stretch DNA molecules and lower their conformational entropy. The sieving mechanism of entropic recoil, proposed by Cabodi et al. [1], will be implemented using an array of elastomeric nanocheannels. Structures of various dimensions are fabricated taking advantage of replica molding techniques, starting from Focused Ion Beam (FIB) patterned silicon substrates. Poly(dimethylsiloxane) (PDMS) and hard-PDMS [2] are used to replicate the features on the silicon mold. After plasma oxidation the nanochannels are sealed using a glass cover slip. A piezoelectric system will be integrated on the device in order to exploit the elastomeric propertis of PDMS, reversibly deform the nanochannels and tune their cross section. This system will allow a dynamic variation of the confinement conditions affecting molecules mobility inside the nanochannels.
