Aldo Romani

A Nanocurrent Power Management IC for Multiple Heterogeneous Energy Harvesting Sources

This paper presents a fully autonomous power converter IC for energy harvesting from multiple and multitype sources, such as piezoelectric, photovoltaic, thermoelectric, and RF transducers. The converter performs an independent self-adapting input power tracking process for each source. The peak power conversion efficiency measured during single-source operation is 89.6%. With all sources enabled, the intrinsic current consumption is as low as 47.9 nA/source. A self-starting battery-less architecture has been implemented in a 0.32-μm STMicroelectronics BCD technology with a 2142 μm × 2142 μm die area. The IC only requires a single-shared inductor and an external storage capacitor for the basic working configuration. With respect to other multisource energy harvesters, this design specifically introduces a series of nanopower design techniques for extreme minimization of the intrinsic consumption during operation. The small chip size combined with the limited number of required external component, the high conversion efficiency, and the state-of-the-art intrinsic nanocurrent consumption make the IC suitable for many critical applications with very limited available power, such as wearable devices or unobtrusive wireless sensor networks.

A Nanopower Synchronous Charge Extractor IC for Low-Voltage Piezoelectric Energy Harvesting With Residual Charge Inversion

The paper presents a power converter for piezoelectric energy harvesting implementing a modified version of a synchronous electrical charge extraction with quiescent current as low as 160 nA. The input energy is increased of more than 200% for weak vibrations, by inverting the residual charge left on the capacitance of the transducer after each energy extraction. Moreover, a power management policy, named two-way energy storage, is introduced in order to improve significantly the efficiency of the energy harvesting system in battery-less systems during the startup phase, when the energy storage is fully depleted. The converter behaves as a buck-boost converter, and the measured peak efficiency is 85.3%. The IC has been designed in a 0.32-μm microelectronic technology from STMicroelectronics in an active area of 0.95 mm2.

Programmable interactions of functionalized single bioparticles in a dielectrophoresis-based microarray chip

Manipulating single biological objects is a major unmet challenge of biomedicine. Herein, we describe a lab-on-a-chip platform based on dielectrophoresis (DEP). The DEParray is a prototypal version consisting of 320 × 320 arrayed electrodes generating >10,000 spherical DEP cages. It allows the capture and software-guided movement to predetermined spatial coordinates of single biological objects. With the DEParray we demonstrate (a) forced interaction between a single, preselected target cell and a programmable number of either microspheres or natural killer (NK) cells, (b) on-chip immunophenotypic discrimination of individual cells based on differential rosetting with microspheres functionalized with monoclonal antibodies to an inhibitory NK cell ligand (HLA-G), (c) on-chip, real-time (few minutes) assessment of immune lysis by either visual inspection or semiautomated, time-lapse reading of a fluorescent dye released from NK cell-sensitive targets, and (d) manipulation and immunophenotyping with limiting amounts (about 500) cells. To our knowledge, this is the first report describing a DEP-based lab-on-a-chip platform for the quick, arrayed, software-guided binding of individually moved biological objects, the targeting of single cells with microspheres, and the real-time characterization of immunophenotypes. The DEParray candidates as a discovery tool for novel cell:cell interactions with no prior (immuno)phenotypic knowledge.

Modeling, Design, and Fabrication of High-Inductance Bond Wire Microtransformers With Toroidal Ferrite Core

This paper presents the design of miniaturized bond wire transformers assembled with standard IC bonding wires and NiZn and MnZn ferrite toroidal cores. Several prototypes are fabricated on a printed circuit board substrate with various layouts in a 4.95 mm × 4.95 mm area. The devices are modeled by analytical means and characterized with impedance measurements over a wide frequency range. Experimental results on 1:38 device show that the secondary self-inductance increases from 0.3 μH with aircore to 315 μH with ferrite core; the coupling coefficient improves from 0.1 with air-core to 0.9 with ferrite core; the effective turns ratio enhances from 0.5 with air-core to 34 with ferrite core. This approach is cost effective and enables a flexible design of efficient micromagnetics on top of ICs with dc inductance to resistance ratio of 70 μH/Ω and an inductance per unit area of 12.8 μH/mm2 up to 0.3 MHz. The design targets the development of bootstrap circuits for ultralow voltage energy harvesting. In this context, a low-voltage step-up oscillator suitable for thermoelectric generator sources is realized with a commercial IC and the proposed microtransformers. Experimental measurements on a discrete prototype report that the circuit bootstraps from voltages down to 260 mV and outputs a dc voltage of 2 V.

Design and fabrication of a 315 μΗ bondwire micro-transformer for ultra-low voltage energy harvesting

This paper presents a design study of a new topology for miniaturized bondwire transformers fabricated and assembled with standard IC bonding wires and toroidal ferrite (Fair-Rite 5975000801) as a magnetic core. The microtransformer realized on a PCB substrate, enables the build of magnetics on-top-of-chip, thus leading to the design of high power density components. Impedance measurements in a frequency range between 100 kHz to 5 MHz, show that the secondary self-inductance is enhanced from 0.3 μH with an epoxy core to 315 μH with the ferrite core. Moreover, the micro-machined ferrite improves the coupling coefficient from 0.1 to 0.9 and increases the effective turns ratio from 0.5 to 35. Finally, a low-voltage IC DC-DC converter solution, with the transformer mounted on-top, is proposed for energy harvesting applications.

A Long-Distance RF-Powered Sensor Node with Adaptive Power Management for IoT Applications

We present a self-sustained battery-less multi-sensor platform with RF harvesting capability down to −17 dBm and implementing a standard DASH7 wireless communication interface. The node operates at distances up to 17 m from a 2 W UHF carrier. RF power transfer allows operation when common energy scavenging sources (e.g., sun, heat, etc.) are not available, while the DASH7 communication protocol makes it fully compatible with a standard IoT infrastructure. An optimized energy-harvesting module has been designed, including a rectifying antenna (rectenna) and an integrated nano-power DC/DC converter performing maximum-power-point-tracking (MPPT). A nonlinear/electromagnetic co-design procedure is adopted to design the rectenna, which is optimized to operate at ultra-low power levels. An ultra-low power microcontroller controls on-board sensors and wireless protocol, to adapt the power consumption to the available detected power by changing wake-up policies. As a result, adaptive behavior can be observed in the designed platform, to the extent that the transmission data rate is dynamically determined by RF power. Among the novel features of the system, we highlight the use of nano-power energy harvesting, the implementation of specific hardware/software wake-up policies, optimized algorithms for best sampling rate implementation, and adaptive behavior by the node based on the power received.

Doing a Lot with a Little: Micropower Conversion and Management for Ambient-Powered Electronics

The microelectronic components integral to connecting objects in the Internet of Things require efficient power supplies. One solution is to harvest energy from the objects environment, and researchers are actively tackling problems in integrated power conversion and management to realize the vision of nanopower devices.

Optimum Design Rules for CMOS Hall Sensors

This manuscript analyzes the effects of design parameters, such as aspect ratio, doping concentration and bias, on the performance of a general CMOS Hall sensor, with insight on current-related sensitivity, power consumption, and bandwidth. The article focuses on rectangular-shaped Hall probes since this is the most general geometry leading to shape-independent results. The devices are analyzed by means of 3D-TCAD simulations embedding galvanomagnetic transport model, which takes into account the Lorentz force acting on carriers due to a magnetic field. Simulation results define a set of trade-offs and design rules that can be used by electronic designers to conceive their own Hall probes.

A Sub-μ A Stand-By Current Synchronous Electric Charge Extractor for Piezoelectric Energy Harvesting

In the field of energy harvesting there is a growing interest in power management circuits with intrinsic sub-μ A current consumptions, in order to operate efficiently with very low levels of available power. In this context, integrated circuits proved to be a viable solution with high associated nonrecurring costs and design risks. As an alternative, this article presents a fully autonomous and battery-less circuit solution for piezoelectric energy harvesting based on discrete components in a low-cost PCB technology, which achieves a comparable performance in a 32 × 43 mm2 footprint. The power management circuit implements synchronous electric charge extraction (SECE) with a passive bootstrap circuit from fully discharged states. Circuit characterization showed that the circuit consumes less than 1μ A with a 3V output and may achieve energy conversion efficiencies of up to 85%. In addition, the circuit is specifically designed for operating with input and output voltages up to 20V, which grants a significant flexibility in the choice of transducers and energy storage capacitors.

A −8 mV/+15 mV Double Polarity Piezoelectric Transformer-Based Step-Up Oscillator for Energy Harvesting Applications

This paper presents two circuit topologies of battery-less integrated boost oscillators suitable for kick-starting electronic systems in fully discharged states with ultra-low input voltages, in the context of energy harvesting applications based on thermoelectric generators, by coupling a piezoelectric transformer in a feedback loop. With respect to the prior work, the first presented solution is a double polarity circuit designed in a <inline-formula> <tex-math notation=LaTeX>