Benoit Charlot

Bio: Benoit Charlot is an academic researcher from University of Montpellier. The author has contributed to research in topics: Bulk micromachining & Scanning thermal microscopy. The author has an hindex of 22, co-authored 120 publications receiving 1836 citations. Previous affiliations of Benoit Charlot include Civilian Marksmanship Program & University of Tokyo.

Scanning thermal imaging of microelectronic circuits with a fluorescent nanoprobe

Abstract: We have developed a scanning thermal imaging method that uses a fluorescent particle as a temperature sensor. The particle, which contains rare-earth ions, is glued at the end of an atomic force microscope tip and allows the determination of the temperature of its surrounding medium. The measurement is performed by comparing the relative integrated intensity of two fluorescence lines that have a well-defined temperature dependence. As an example of application, we show the temperature map on an operating complementary metal-oxide-semiconductor integrated circuit.

Bistable nanowire for micromechanical memory

Abstract: We present a micromechanical device designed to be used as a non-volatile mechanical memory. The structure is composed of a suspended slender nanowire (width: 100 nm, thickness: 430 nm, length: 8 to 30 ?m) clamped at both ends. Electrodes are placed on each side of the nanowire to (1) actuate the structure during the data writing and erasing mode and (2) determine its position by measuring the capacitive bridge in the reading mode. The structure is patterned by electron beam lithography on a pre-stressed thermally grown silicon dioxide layer. When later released by plasma etching, the stressed material relaxes and the beam buckles by itself to a position of lower energy. These symmetric bistable Euler beams exhibit two stable deformed. This paper presents the microfabrication process and analysis of the static buckling of nanowires. Snapping of these nanowires from one stable position to another by mechanical or electrical means will also be discussed.

Fabrication and characterization of high damping electrostatic micro devices for vibration energy scavenging

Abstract: Advances in low power electronics and microsystems design open up the possibility to power small wireless sensor nodes thanks to energy scavenging techniques. Among the potential energy sources, we have focused on mechanical surrounding vibrations. To convert vibrations into electrical power we have chosen mechanical structures based on electrostatic transduction. Thanks to measurements and in agreement with recent studies [1], we have observed that most of surrounding mechanical vibrations occurs at frequencies below 100 Hz. We report here global simulations and designs of mechanical structures able to recover power over a large spectrum below 100 Hz. Contrary to existing structures tuned on a particular frequency [2], we have investigated conversion structures with a high electrical damping. Mathematica analytical models have been performed to determine the mechanical and electrical parameters that maximize the scavenged power for a wide number of applications (Figure 3). Two prototypes of mechanical structures have been designed.

Wireless sensor network node with asynchronous architecture and vibration harvesting micro power generator

Abstract: This paper presents recent advances in the development of a microsystem designed to be part of a wireless sensor network. This microsystem is developed with two particular technologies: asynchronous circuits and ambient energy harvesting power generator. Asynchronous technologies offer several advantages allowing a global decrease in the power consumption of the node. In addition, the presence of an ambient energy scavenger allows the system to power itself, thus reducing maintenance and increasing the lifetime of the node.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Energy harvesting vibration sources for microsystems applications

Abstract: This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric, electromagnetic and electrostatic. Piezoelectric generators employ active materials that generate a charge when mechanically stressed. A comprehensive review of existing piezoelectric generators is presented, including impact coupled, resonant and human-based devices. Electromagnetic generators employ electromagnetic induction arising from the relative motion between a magnetic flux gradient and a conductor. Electromagnetic generators presented in the literature are reviewed including large scale discrete devices and wafer-scale integrated versions. Electrostatic generators utilize the relative movement between electrically isolated charged capacitor plates to generate energy. The work done against the electrostatic force between the plates provides the harvested energy. Electrostatic-based generators are reviewed under the classifications of in-plane overlap varying, in-plane gap closing and out-of-plane gap closing; the Coulomb force parametric generator and electret-based generators are also covered. The coupling factor of each transduction mechanism is discussed and all the devices presented in the literature are summarized in tables classified by transduction type; conclusions are drawn as to the suitability of the various techniques.

A review of power harvesting using piezoelectric materials (2003–2006)

Abstract: The field of power harvesting has experienced significant growth over the past few years due to the ever-increasing desire to produce portable and wireless electronics with extended lifespans. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their limited lifespan, thus necessitating their periodic replacement. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of a disposable nature to allow the device to function over extended periods of time. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. A number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy. While each of these sources of energy can be effectively used to power remote sensors, the structural and biological communities have placed an emphasis on scavenging vibrational energy with piezoelectric materials. This article will review recent literature in the field of power harvesting and present the current state of power harvesting in its drive to create completely self-powered devices.

Energy Harvesting From Human and Machine Motion for Wireless Electronic Devices

Abstract: Energy harvesting generators are attractive as inexhaustible replacements for batteries in low-power wireless electronic devices and have received increasing research interest in recent years. Ambient motion is one of the main sources of energy for harvesting, and a wide range of motion-powered energy harvesters have been proposed or demonstrated, particularly at the microscale. This paper reviews the principles and state-of-art in motion-driven miniature energy harvesters and discusses trends, suitable applications, and possible future developments.

A micro electromagnetic generator for vibration energy harvesting

Abstract: Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes This paper presents a small (component volume 01 cm3, practical volume 015 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data The generator uses four magnets arranged on an etched cantilever with a wound coil located within the moving magnetic field Magnet size and coil properties were optimized, with the final device producing 46 µW in a resistive load of 4 k? from just 059 m s-2 acceleration levels at its resonant frequency of 52 Hz A voltage of 428 mVrms was obtained from the generator with a 2300 turn coil which has proved sufficient for subsequent rectification and voltage step-up circuitry The generator delivers 30% of the power supplied from the environment to useful electrical power in the load This generator compares very favourably with other demonstrated examples in the literature, both in terms of normalized power density and efficiency