MEMS piezoelectric vibrational energy harvesters and circuits for IoT applications

In the Internet of Things (IoT) world, more and more sensor nodes are being deployed and more mobile power sources are required. Alternative solutions to batteries are the subjects of worldwide extended research. Among the possibilities is the harvesting of energy from the ambient. A novel energy harvesting system to power wireless sensor nodes is a necessity and inevitable path, with more and more market interest. Microelectromechnaical systems (MEMS) based piezoelectric vibrational energy harvesters (PVEH) are considered in this thesis due to their good energy densities, conversion efficiency, suitability for miniaturization and CMOS integration. Cantilever beams are favored for their relatively high average strains, low frequencies and simplicity of fabrication. Proof masses are essential in micro scale devices in order to decrease the resonance frequency and increase the strain along the beam to increase the output power. In this thesis, the effects of proof mass geometry on piezoelectric vibration energy harvesters are studied. Different geometrical dimension ratios have significant impact on the resonance frequency, e.g., beam to mass lengths, and beam to mass widths. The responses of various prototypes are studied. Furthermore, the impact of geometry on the performance of cantilever-based PVEH is investigated. Namely, rectangular and trapezoidal T-shaped designs are fabricated and tested. Optimized cross-shaped geometries are fabricated using a commercial technology PiezoMUMPs process from MEMSCAP. They are characterized for their resonant frequency, strain distribution and output power. The output of an energy harvester is not directly suited as a power supply for circuits because of variations in its power and voltage over time, therefore a power management circuit is required. The circuit meets the requirements of responding to an input voltage that varies with the ambient conditions to generate a regulated output voltage, and the ability to power multiple outputs from a fixed input voltage. In this thesis, new design architectures for a reconfigurable circuit are considered. A charge pump which modifies dynamically the number of stages to generate a plurality of voltage levels has been designed and fabricated using a CMOS 0.13 μm technology. This provides biasing voltages for electrostatic MEMS devices. Electrostatic MEMS require relatively high and variable actuation voltages and the fabricated circuit serves this goal and attains a measured maximum output voltage of 10.1 V from a 1.2 V supply. In this thesis, design recommendations are given and MEMS piezoelectric harvesters are implemented and validated through fabrications. T-shaped harvesters bring improvements over cantilever designs, namely the trapezoidal T-shaped structures. A cross-shaped design has the advantage of utilizing four beams and the proposed proof mass improves the performance significantly. A cross-coupled circuit rectifies the output efficiently towards an optimal energy harvesting solution

A Memory-Targeted Dynamic Reconfigurable Charge Pump to Achieve a Power Consumption Reduction in IoT Nodes

Targeting the more recently adopted low-power memories for data-logging operation in IoT nodes, this paper presents a simple reconfigurable dual-branch cross-coupled charge pump (CP) topology in which clock amplitude scaling and modulation of the number of stages are exploited to improve power efficiency and/or change the output voltage without degrading speed performance. The proposed solution allows a reduction of the power conversion losses, maintaining speed, maximum output voltage and silicon area unaltered as compared to the conventional charge pump. Post-layout simulation results confirm the effectiveness of the proposed topology which can be adapted to any other kind of linear charge pump

Design of programmable matter

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (leaves 115-119).Programmable matter is a proposed digital material having computation, sensing, actuation, and display as continuous properties active over its whole extent. Programmable matter would have many exciting applications, like paintable displays, shape-changing robots and tools, rapid prototyping, and sculpture-based haptic interfaces. Programmable matter would be composed of millimeter-scale autonomous microsystem particles, without internal moving parts, bound by electromagnetic forces or an adhesive binder. Particles can dissipate 10 mW heat, and store 6 J energy in an internal zinc-air battery. Photovoltaic cells provide 300 [mu]W outdoors and 3.0 [mu]W indoors. Painted systems can store battery reactants in the paint binder; 6 J / mm3 can be stored, and diffusion is fast enough to transport reactants to the particles. Capacitive power transfer is an efficient method to transfer power to sparse, randomly placed particles. Power from capacitive transfer is proportional to VDD 2: 100[mu]W at 3.3V and 12 mW at 35V. Inter-particle communication is possible via optical, near-field, and far-field electromagnetic systems. Optical systems allow communication with low area (sub-mm) particles, and 24 pJ/bit. Near-field electromagnetic gives precisely controlled neighborhoods, localization capability, and 37 pJ/bit. Far-field radio communication between widely spaced particles may be possible at 60 GHz; antennas that fit inside 1 mm3 exist; complete transceivers do not. A 32-bit CPU uses less than 0.26 mm2 die area, 256K x 8 SRAM uses 1.1 mm2, and 256K x 8 FLASH uses 0.32 mm2. Direct-drive electric and magnetic field systems allow actuation without moving parts inside the particles. Magnetic surface-drive motors designed for operation without bearings are not power-efficient, and parasitic interactions between permanent magnets may limit their usefulness at millimeter particle dimensions. Electrostatic surface-drive motors are power-efficient, but practical only at particle dimensions below a few millimeters. We constructed a prototype paintable display; a distributed PostScript rendering system with 1000 randomly-placed 3.4 cm nodes, each with a CPU, IR communications, and LED. The system is used to render the letter "A." We present a design, not yet constructed, for a literal paintable display, with 1.0 mm rendering particles, each with a microprocessor and memory, and 110 [mu]m display particles, with tri-color LED's and simpler circuitry. Storage of zinc-air battery reactants in the paint binder would provide an 8 hour battery life, and capacitive power distribution would allow continuous operation. We constructed a prototype sliding-cube modular robot, with 3.4 cm nodes. The system uses magnetic surface-drive actuation. We demonstrate horizontal lattice-unit translation. We describe a design, not yet constructed, for a sliding-cube modular robot with 2 mm nodes. The cubes use standard-process CMOS IC's, inserted into a cubic space frame and wire-bonded together. Arrays of passivated electrodes, 1 [mu]m from the surface of the cubes, are used for electrostatic surface-drive actuation, zero-power latching, power transfer, localization, and communication. The design allows actuation from any contacting position. Energy is stored in a standard SMT capacitor inside each node, which is recharged by power transfer through chains of contacting nodes.by Ara N. Knaian.S.M

Energy autonomous systems : future trends in devices, technology, and systems

The rapid evolution of electronic devices since the beginning of the nanoelectronics era has brought about exceptional computational power in an ever shrinking system footprint. This has enabled among others the wealth of nomadic battery powered wireless systems (smart phones, mp3 players, GPS, …) that society currently enjoys. Emerging integration technologies enabling even smaller volumes and the associated increased functional density may bring about a new revolution in systems targeting wearable healthcare, wellness, lifestyle and industrial monitoring applications

Microelectromechanical Systems and Devices

The advances of microelectromechanical systems (MEMS) and devices have been instrumental in the demonstration of new devices and applications, and even in the creation of new fields of research and development: bioMEMS, actuators, microfluidic devices, RF and optical MEMS. Experience indicates a need for MEMS book covering these materials as well as the most important process steps in bulk micro-machining and modeling. We are very pleased to present this book that contains 18 chapters, written by the experts in the field of MEMS. These chapters are groups into four broad sections of BioMEMS Devices, MEMS characterization and micromachining, RF and Optical MEMS, and MEMS based Actuators. The book starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices and acoustic biosensors. MEMS characterization, micromachining, macromodels, RF and Optical MEMS switches are discussed in next sections. The book concludes with the emphasis on MEMS based actuators

Advances in Solid State Circuit Technologies

This book brings together contributions from experts in the fields to describe the current status of important topics in solid-state circuit technologies. It consists of 20 chapters which are grouped under the following categories: general information, circuits and devices, materials, and characterization techniques. These chapters have been written by renowned experts in the respective fields making this book valuable to the integrated circuits and materials science communities. It is intended for a diverse readership including electrical engineers and material scientists in the industry and academic institutions. Readers will be able to familiarize themselves with the latest technologies in the various fields

Development of electronics for microultrasound capsule endoscopy

Development of intracorporeal devices has surged in the last decade due to advancements in the semiconductor industry, energy storage and low-power sensing systems. This work aims to present a thorough systematic overview and exploration of the microultrasound (µUS) capsule endoscopy (CE) field as the development of electronic components will be key to a successful applicable µUSCE device. The research focused on investigating and designing high-voltage (HV, < 36 V) generating and driving circuits as well as a low-noise amplifier (LNA) for battery-powered and volume-limited systems. In implantable applications, HV generation with maximum efficiency is required to improve the operational lifetime whilst reducing the cost of the device. A fully integrated hybrid (H) charge pump (CP) comprising a serial-parallel (SP) stage was designed and manufactured for > 20 V and 0 - 100 µA output capabilities. The results were compared to a Dickson (DKCP) occupying the same chip area; further improvements in the SPCP topology were explored and a new switching scheme for SPCPs was introduced. A second regulated CP version was excogitated and manufactured to use with an integrated µUS pulse generator. The CP was manufactured and tested at different output currents and capacitive loads; its operation with an US pulser was evaluated and a novel self-oscillating CP mechanism to eliminate the need of an auxiliary clock generator with a minimum area overhead was devised. A single-output universal US pulser was designed, manufactured and tested with 1.5 MHz, 3 MHz, and 28 MHz arrays to achieve a means of fully-integrated, low-power transducer driving. The circuit was evaluated for power consumption and pulse generation capabilities with different loads. Pulse-echo measurements were carried out and compared with those from a commercial US research system to characterise and understand the quality of the generated pulse. A second pulser version for a 28 MHz array was derived to allow control of individual elements. The work involved its optimisation methodology and design of a novel HV feedback-based level-shifter. A low-noise amplifier (LNA) was designed for a wide bandwidth µUS array with a centre frequency of 28 MHz. The LNA was based on an energy-efficient inverter architecture. The circuit encompassed a full power-down functionality and was investigated for a self-biased operation to achieve lower chip area. The explored concepts enable realisation of low power and high performance LNAs for µUS frequencies

EUROSENSORS XVII : book of abstracts

Fundação Calouste Gulbenkien (FCG).Fundação para a Ciência e a Tecnologia (FCT)