Francesco Orfei

A real vibration database for kinetic energy harvesting application

In this article, we discuss the project of a vibration signal database for energy harvesting purpose. After a brief description where we present the technologies used to create the database and the procedures to acquire the signals, we show some results obtained using selected environmental noises from the database to characterize nonlinear energy harvesters.

A Low-Cost Driving Circuitry for Permittivity and Moisture Measurement Systems

The implementation of a low cost driving electronic for a permittivity measurement system employing resonant microwave sensors is presented in this paper. The complete driving electronics needed to perform scalar measurements is described and its components are illustrated and characterized. The measurement results and accuracy have been compared with commercial devices showing similar performances

Nonlinear Kinetic Energy Harvesting

Abstract Harvesting of kinetic energy present in the form of random vibrations is an interesting option due to the almost universal presence of this kind of motion. Traditional generators based on piezoelectric effect are built with linear oscillators made by a piezoelectric beam and a mass used to tune the resonance frequency on the predominant frequency of the vibrations spectrum. However, in most cases the ambient random vibrations have their energy distributed over a wide spectrum of frequencies, being rich especially at low frequency. Furthermore frequency tuning is not always possible due to geometrical/dynamical constraints. In this work we present a different method based on the exploitation of the nonlinear dynamical features of bistable oscillator. The experimental results and the digital simulations show that nonlinear harvester (e.g. bistable oscillators) can overcome some of the most severe limitations of generators based on linear dynamics.

Vibration Energy Harvesting: Linear and Nonlinear Oscillator Approaches

An important question that must be addressed by any energy harvesting technology is related to the type of energy available (Paradiso et al., 2005; Roundy et al., 2003). Among the renewable energy sources, kinetic energy is undoubtedly the most widely studied for applications to the micro-energy generation1. Kinetic energy harvesting requires a transduction mechanism to generate electrical energy from motion. This can happen via a mechanical coupling between the moving body and a physical device that is capable of generating electricity in the form of an electric current or of a voltage difference. In other words a kinetic energy harvester consists of a mechanical moving device that converts displacement into electric charge separation.

Hybrid autonomous transceivers

A small photocell and a non-linear vibration energy harvester have been used to power a low power wireless transceiver device. The device, a technology demonstrator, is self-powered and works without any battery on board. It is able to transmit at few meters distance data such as the temperature and the power supply voltage values in the 2,4 GHz ISM band every 10 seconds.

Energy harvesting from structural vibrations of magnetic shape memory alloys

This letter presents the idea of scavenging energy from vibrating structures through magnetic shape memory alloy (MSMA). To this end, a MSMA specimen made of Ni50Mn28Ga22 is coupled to a cantilever beam through a step. Two permanent magnets installed at the top and bottom of the beam create a bias field perpendicular to the magnetization axis of the specimen. When vibrating the device, a longitudinal axial load applies on the MSMA, which in turn changes the magnetization, due to the martensitic variant reorientation mechanism. A pick-up coil wounded around the MSMA converts this variation into voltage according to the Faradays law. Experimental test confirms the possibility of generating voltage in a vibrating MSMA. In particular, 15 μW power is harvested for acceleration of 0.3 g RMS at a frequency of 19.1 Hz, which is comparable with piezoelectric energy harvesters. It is also found that the optimum bias magnetic field for maximum voltage is lower than the starting field of pseudo elastic behavior.

Vibrations powered LoRa sensor: An electromechanical energy harvester working on a real bridge

In this paper we present a battery less LoRa wireless sensor to monitor the road condition measuring the temperature of the asphalt and the presence of water or rain. This system is powered by the energy provided by an electromagnetic vibration energy harvester based on Halbach configuration. A LoRa transceiver require much more energy than a short range one [1] but it enables the monitoring of a large structures like a bridge from distance. Electromagnetic generator represents a cost effective and easily scalable solution with respect the use of a piezoelectric material. We propose the design of the energy harvester, of the power conditioning circuitry and of the electronics of the wireless node. We also discuss the energy budget of the system to send data about the condition of the asphalt on the bridge.

Circuitry for nonlinear vibration energy harvesting

Nonlinear vibration energy harvesting is becoming a technology more and more important. Generally vibrations are spread over hundreds or thousands of hertz, making impractical the use of tuned systems. Real world vibrations are even not constant in amplitude, and this makes hard to design a high efficiency electrical energy rectifier and regulator due to the non constant RMS value of the input energy. In this paper is described the solution adopted for a wireless sensor for the automotive market, powered by a nonlinear bi-stable vibration energy harvester.

A microwave sensor for glue on paper detection

A microwave sensor for glue on paper detection for industrial application has been developed. It uses a resonant cavity to detect and measure the amount of glue placed on a dielectric layer, for example a sheet of paper. It works in the ISM band, at 2.45 GHz. It can be used for the control of the industrial gluing for the mailing and packaging sector.

Nonlinear Bi-Stable Vibration Energy Harvester at Work

An extreme low power energy rectification, storage and management circuitry has been developed and used to power a small digital wireless sensor with a piezoelectric non-linear bi-stable vibration energy harvester for automotive application. All the system has been designed with off-the-shelf components and sends data in the 2.4 GHz band.