A Parameterization Scheme for Lossy Transmission Line Macromodels with Application to High Speed Interconnects in Mobile Devices

We introduce a novel parameterization scheme based on the generalized method of characteristics (MoC) formacromodels of transmission-line structures having a cross section depending on several free geometrical and material parameters. This situation is common in early design stages, when the physical structures still have to be finalized and optimized under signal integrity and electromagnetic compatibility constraints. The topology of the adopted line macromodels has been demonstrated to guarantee excellent accuracy and efficiency. The key factors are propagation delay extraction and rational approximations, which intrinsically lead to a SPICE-compatible macromodel stamp. We introduce a scheme that parameterizes this stamp as a function of geometrical and material parameters such as conductor-width and separation, dielectric thickness, and permettivity. The parameterization is performed via multidimensional interpolation of the residue matrices in the rational approximation of characteristic admittance and propagation operators. A significant advantage of this approach consists of the possibility of efficiently utilizing the MoC methodology in an optimization scheme and eventually helping the design of interconnects.We apply the proposed scheme to flexible printed interconnects that are typically found in portable devices having moving parts. Several validations demonstrate the effectiveness of the approac

Energy and power

Renewable energy - portable energy sources The increasing need for portable energy storage density due to the growing number of miniaturized and thin devices is driving the current development of energy storage in phones and other portable devices [1]. Figure 3.1 shows the development from the mobile phones of the 1990s to the multimedia centers of two decades later, and the evident development of the devices to thinner and more flexible forms. The total power consumption will become even more important when more electronic devices are embedded in the environment. Also with standalone devices designed to operate without mains power supply for long periods, like years, there are new requirements. Energy storage and power management are among the top three issues for customers and developers in current and future mobile multimedia portable devices. Improvements in conventional battery at the current yearly level are not expected to provide enough energy density to meet all the requirements of future multimedia portables. Even though the use of cellular radio frequency (RF) engine power is expected to reduce with integrated circuit (IC) process and intelligent circuit development, the increasing number of radios and integration of new digital radio, video, and multimedia broadcasting (DAB, DVB-H, DMB) and channel decoders represents a significant challenge both in terms of energy consumption and component costs. Adding wireless local area network (WLAN) and local radio capabilities increases the overall power consumption of smartphones that are already suffering from high energy drain due to the high power consumption of 2.5G/3G wireless modules

Enhanced supercapacitors from hierarchical carbon nanotube and nanohorn architectures

Supercapacitors fill the power and energy gap between electrolytic capacitors and batteries. The energy density for commercial supercapacitors is currently limited to similar to 5 Wh kg similar to 1. Enhancing the energy and power density of supercapacitors is of great interest as it would open up a much wider range of applications. In this work, thin film supercapacitors made of random networks of single-walled carbon nanotubes (SWNTs) were enhanced by the use of carbon nanoparticles of a size ideal to fill the pores in the SWNT network. These nanoparticles, termed carbon nanohorns (CNHs), provide a much enhanced surface area, whilst maintaining high permeability and porosity. We demonstrate the hierarchical use of carbon nanostructures in a controlled fashion, allowing an enhancement provided by both types of materials, high power density by the SWNTs and high energy density from the CNHs. SWNT films serve as an ideal template onto which CNHs are deposited, with a good size match, adhesion and charge transfer between particles of a single chemical species. This combination results in an enhanced specific capacitance and a reduced equivalent series resistance (ESR) compared to a capacitor made of either individual component. Additionally, the good binding properties of the hybrid material and the high electrical conductivity of the SWNTs permit the removal of both the binder and the charge collector, paving the way for thinner and lighter supercapacitors. These electrodes allow the fabrication of supercapacitors with novel properties. As an example, we demonstrate a semitransparent supercapacitor. These results demonstrate the possibilities that may be available for the enhancement of electrodes by tailoring and combining relevant materials hierarchically in multiple scales. Much potential remains in further enhancement through tailored hierarchical nanostructuring

Nanomaterial-Enhanced All-Solid Flexible Zinc-Carbon Batteries

Solid-state and flexible zinc carbon (or Leclanche) batteries are fabricated using a combination of functional nanostructured materials for optimum performance. Flexible carbon nanofiber mats obtained by electrospinning are used as a current collector and cathode support for the batteries. The cathode layer consists of manganese oxide particles combined with single-walled carbon nanotubes for improved conductivity. A polyethylene oxide layer containing titanium oxide nanoparticles forms the electrolyte layer, and a thin zinc foil is used as the anode. The battery is shown to retain its performance under mechanically stressed conditions. The results show that the above configuration can achieve solid-state mechanical flexibility and increased shelf life with little sacrifice in performance

Optimization of an Impact-Based Frequency Up-Converted Piezoelectric Vibration Energy Harvester for Wearable Devices

This work presents a novel development of the impact-based mechanism for piezoelectric vibration energy harvesters. More precisely, the effect of an impacting mass on a cantilever piezoelectric transducer is studied both in terms of the tip mass value attached to the cantilever and impact position to find an optimal condition for power extraction. At first, the study is carried out by means of parametric analyses at varying tip mass and impact position on a unimorph MEMS cantilever, and a suitable physical interpretation of the associated electromechanical response is given. The effect of multiple impacts is also considered. From the analysis, it emerges that the most effective configuration, in terms of power output, is an impact at the cantilever tip without a tip mass. By changing the value of the tip mass, a sub-optimal impact position along the beam axis can also be identified. Moreover, the effect of a tip mass is deleterious on the power performance, contrary to the well-known case of a resonant energy harvester. A mesoscale prototype with a bimorph transducer is fabricated and tested to validate the computational models. The comparison shows a good agreement between numerical models and the experiments. The proposed approach is promising in the field of consumer electronics, such as wearable devices, in which the impact-based device moves at the frequencies of human movement and is much lower than those of microsystems

Wearable Ball-Impact Piezoelectric Multi-Converters for Low-Frequency Energy Harvesting from Human Motion

9siMulti-converter piezoelectric harvesters based on mono-axial and bi-axial configurations are proposed. The harvesters exploit two and four piezoelectric converters (PCs) and adopt an impinging spherical steel ball to harvest electrical energy from human motion. When the harvester undergoes a shake, a tilt, or a combination of the two, the ball hits one PC, inducing an impact-based frequency-up conversion. Prototypes of the harvesters have been designed, fabricated, fastened to the wrist of a person by means of a wristband and watchband, and experimentally tested for different motion levels. The PCs of the harvesters have been fed to passive diode-based voltage-doubler rectifiers connected in parallel to a storage capacitor, Cs = 220 nF. By employing the mono-axial harvester, after 8.5 s of consecutive impacts induced by rotations of the wrist, a voltage vcs (t) of 40.2 V across the capacitor was obtained, which corresponded to a stored energy of 178 µJ. By employing the bi-axial harvester, the peak instantaneous power provided by the PCs to an optimal resistive load was 1.58 mW, with an average power of 9.65 µW over 0.7 s. The proposed harvesters are suitable to scavenge electrical energy from low-frequency nonperiodical mechanical movements, such as human motion.nonenoneNastro A.; Pienazza N.; Bau M.; Aceti P.; Rouvala M.; Ardito R.; Ferrari M.; Corigliano A.; Ferrari V.Nastro, A.; Pienazza, N.; Bau, M.; Aceti, P.; Rouvala, M.; Ardito, R.; Ferrari, M.; Corigliano, A.; Ferrari, V