Maximum Effectiveness of Electrostatic Energy Harvesters When Coupled to Interface Circuits

Accepted versio

Design, Fabrication and Characterization of a Piezoelectric Microgenerator Including a Power Management Circuit

We report in this paper the design, fabrication and experimental characterization of a piezoelectric MEMS microgenerator. This device scavenges the energy of ambient mechanical vibrations characterized by frequencies in the range of 1 kHz. This component is made with Aluminum Nitride thin film deposited with a CMOS compatible process. Moreover we analyze two possible solutions for the signal rectification: a discrete doubler-rectifier and a full custom power management circuit. The ASIC developed for this application takes advantage of diodes with very low threshold voltage and therefore allows the conversion of extremely low input voltages corresponding to very weak input accelerations. The volume of the proposed generator is inferior to 1mm3 and the generated powers are in the range of 1$\mu$W. This system is intended to supply power to autonomous wireless sensor nodes.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

A 2 degree-of-freedom SOI-MEMS translation stage with closed loop positioning

This research contains the design, analysis, fabrication, and characterization of a closed loop XY micro positioning stage. The XY micro positioning stage is developed by adapting parallel-kinematic mechanisms, which have been widely used for macro and meso scale positioning systems, to silicon-based micropositioner. Two orthogonal electrostatic comb drives are connected to moving table through 4-bar mechanism and independent hinges which restrict unwanted rotation in 2-degree-of-freedom translational stage. The XY micro positioning stage is fabricated on SOI wafer with three photolithography patterning processes followed by series of DRIE etching and HF etching to remove buried oxide layer to release the end-effector of the device. The fabricated XY micro positioning stage is shown in Fig1 with SEM images. The device provides a motion range of 20 microns in each direction at the driving voltage of 100V. The resonant frequency of the XY stage under ambient conditions is 811 Hz with a high quality factor of 40 achieved from parallel kinematics. The positioning loop is closed using a COTS capacitance-to-voltage conversion IC and a PID controller built in D-space is used to control position with an uncertainty characterized by a standard distribution of 5.24nm and a approximate closed-loop bandwidth of 27Hz. With the positioning loop, the rise time and settling time for closed-loop system are 50ms and 100ms. With sinusoidal input of ω=1Hz, the maximum phase difference of 108nm from reference input is obtained with total motion range of 8μm

Maximum performance of piezoelectric energy harvesters when coupled to interface circuits

This paper presents a complete optimization of a piezoelectric vibration energy harvesting system, including a piezoelectric transducer, a power conditioning circuit with full semiconductor device models, a battery and passive components. To the authors awareness, this is the first time and all of these elements have been integrated into one optimization. The optimization is done within a framework, which models the combined mechanical and electrical elements of a complete piezoelectric vibration energy harvesting system. To realize the optimization, an optimal electrical damping is achieved using a single-supply pre-biasing circuit with a buck converter to charge the battery. The model is implemented in MATLAB and verified in SPICE. The results of the full system model are used to find the mechanical and electrical system parameters required to maximize the power output. The model, therefore, yields the upper bound of the output power and the system effectiveness of complete piezoelectric energy harvesting systems and, hence, provides both a benchmark for assessing the effectiveness of existing harvesters and a framework to design the optimized harvesters. It is also shown that the increased acceleration does not always result in increased power generation as a larger damping force is required, forcing a geometry change of the harvester to avoid exceeding the piezoelectric breakdown voltage. Similarly, increasing available volume may not result in the increased power generation because of the difficulty of resonating the beam at certain frequencies whilst utilizing the entire volume. A maximum system effectiveness of 48% is shown to be achievable at 100 Hz for a 3.38-cm3 generator

Microsystems technology: objectives

This contribution focuses on the objectives of microsystems technology (MST). The reason for this is two fold. First of all, it should explain what MST actually is. This question is often posed and a simple answer is lacking, as a consequence of the diversity of subjects that are perceived as MST. The second reason is that a map of the somewhat chaotic field of MST is needed to identify sub-territories, for which standardization in terms of system modules an interconnections is feasible. To define the objectives a pragmatic approach has been followed. From the literature a selection of topics has been chosen and collected that are perceived as belonging to the field of MST by a large community of workers in the field (more than 250 references). In this way an overview has been created with `applications¿ and `generic issues¿ as the main characteristics

Top-Down Behavioral Modeling Methodology of a Piezoelectric Microgenerator For Integrated Power Harvesting Systems

In this study, we developed a top/down methodology for behavioral and structural modeling of multi-domain microsystems. Then, we validated this methodology through a study case : a piezoelectric microgenerator. We also proved the effectiveness of VHDL-AMS language not only for modeling in behavioral and structural levels but also in writing physical models that can predict the experimental results. Finally, we validated these models by presenting and discussing simulations results.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838