Publications de Robert Andrew Lockhart

Nonlinear piezoelectric vibration energy harvester with frequency-tuned impacting resonators for improving broadband performance at low frequencies

Nico de Rooij, Robert Andrew Lockhart, Danick Briand, Andres Felipe Vasquez Quintero

The paper reports on a nonlinear frequency up-converting vibration energy harvester with enhanced broadband performance below 50 Hz, which is attained by leveraging vibro-impact interaction between two high-frequency piezoelectric generators and two low-fr ...

IOP PUBLISHING LTD2019

A low-cost UWB sensor node powered by a piezoelectric harvester or solar cells

Nico de Rooij, Anja Skrivervik, Pierre-André Farine, Robert Andrew Lockhart, Danick Briand, Cyril Botteron, Christian Robert, Franz-Josef Haug, Pattanaphong Janphuang, Gabriele Tasselli

We propose an autonomous battery-less wireless sensor node that combines on a single printed circuit board an ultra-wideband (UWB) transmitter and its printed antenna, together with a piezoelectric cantilever and a solar cell array to harvest vibrations an ...

Elsevier2016

A Wearable System Of Micromachined Piezoelectric Cantilevers Coupled To A Rotational Oscillating Mass For On-Body Energy Harvesting

Nico de Rooij, Robert Andrew Lockhart, Danick Briand, Pattanaphong Janphuang

In this paper, we present a compact, wearable piezoelectric on-body harvesting system that uses a small eccentric mass from a common watch movement to mechanically deflect a set of micromachined piezoelectric cantilevers when excited by the low frequency m ...

IEEE2014

On The Optimization And Performances Of A Compact Piezoelectric Impact Mems Energy Harvester

Nico de Rooij, Robert Andrew Lockhart, Danick Briand, Pattanaphong Janphuang

This paper presents the development of a compact energy harvesting configuration to convert low frequency, mechanical oscillations into usable electrical energy using AFM-like MEMS piezoelectric cantilevers coupled to a rotating gear. In this approach, one ...

IEEE2014

Flexible and Robust Multilayer Micro-Vibrational Harvesters for High Acceleration Environments

Nico de Rooij, Robert Andrew Lockhart, Danick Briand, Pattanaphong Janphuang, Andres Felipe Vasquez Quintero

This paper presents the fabrication and characterization of multilayer PVDF resonant micro-vibrational energy harvesters designed to withstand environments in which high levels of acceleration are present. The multilayer cantilevers are fabricated by combi ...

Iop Publishing Ltd2013

Multiphysics finite element model of a frequency-amplifying piezoelectric energy harvester with impact coupling for low-frequency vibrations

Nico de Rooij, Robert Andrew Lockhart, Danick Briand, Pattanaphong Janphuang, Andres Felipe Vasquez Quintero

This paper presents experimentally-verified multiphysics finite element model of a wideband vibration energy harvester with impact coupling, which operates on the principle of frequency up-conversion: under low-frequency harmonic base excitation a cantilev ...

Iop Publishing Ltd2013

On the experimental determination of the efficiency of piezoelectric impact-type energy harvesters using a rotational flywheel

Simon Nessim Henein, Nico de Rooij, Robert Andrew Lockhart, Danick Briand, Pattanaphong Janphuang

This paper demonstrates a novel methodology using a rotational flywheel to determine the energy conversion efficiency of the impact based piezoelectric energy harvesters. The influence of the impact speed and additional proof mass on the efficiency is pres ...

Iop Publishing Ltd2013

Optical characterization of fully programmable MEMS diffraction gratings

Michael David Canonica, Wilfried Noell, Robert Andrew Lockhart

We have fabricated and characterized fully programmable diffraction gratings consisting of 64 silicon micro-mirrors. The mirrors are 700 mu m long and 50 mu m wide with a fill factor of 90%. They are actuated electrostatically and move down by 1.25 mu m wh ...

Optical Society of America2012

Development of MEMS Programmable Diffraction Gratings for Spectroscopic Applications in the Visible, Near- and Mid-Infrared

Robert Andrew Lockhart

This work presents the development of two MEMS programmable diffraction gratings designed for spectroscopic applications in the visible, near- and mid-infrared. These devices have been developed to limit distortion of their optical surfaces at rest and thr ...

EPFL2011

Vibration and shock reliability of MEMS: modeling and experimental validation

Herbert Shea, Maurizio Tormen, Robert Andrew Lockhart, Subramanian Sundaram

A methodology to predict shock and vibration levels that could lead to the failure of MEMS devices is reported as a function of vibration frequency and shock pulse duration. A combined experimental–analytical approach is developed, maintaining the simplici ...

Institute of Physics2011