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.

/pdf/energy-harvesting-vibration-sources-for-microsystems-46t885pwdp.pdf

Energy harvesting vibration sources for microsystems applications

Enabling technologies for wireless sensor networks have gained considerable attention in research communities over the past few years. It is highly desirable, even necessary in certain situations, for wireless sensor nodes to be self-powered. With this goal in mind, a vibration based piezoelectric generator has been developed as an enabling technology for wireless sensor networks. The focus of this paper is to discuss the modeling, design, and optimization of a piezoelectric generator based on a two-layer bending element. An analytical model of the generator has been developed and validated. In addition to providing intuitive design insight, the model has been used as the basis for design optimization. Designs of 1 cm3 in size generated using the model have demonstrated a power output of 375 µW from a vibration source of 2.5 m s−2 at 120 Hz. Furthermore, a 1 cm3 generator has been used to power a custom designed 1.9 GHz radio transmitter from the same vibration source.

https://iopscience.iop.org/article/10.1088/0964-1726/13/5/018/pdf

A piezoelectric vibration based generator for wireless electronics

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.

/pdf/energy-harvesting-from-human-and-machine-motion-for-wireless-3lsf4oudvo.pdf

Energy Harvesting From Human and Machine Motion for Wireless Electronic Devices

Starting from human ?sense of touch,? this paper reviews the state of tactile sensing in robotics. The physiology, coding, and transferring tactile data and perceptual importance of the ?sense of touch? in humans are discussed. Following this, a number of design hints derived for robotic tactile sensing are presented. Various technologies and transduction methods used to improve the touch sense capability of robots are presented. Tactile sensing, focused to fingertips and hands until past decade or so, has now been extended to whole body, even though many issues remain open. Trend and methods to develop tactile sensing arrays for various body sites are presented. Finally, various system issues that keep tactile sensing away from widespread utility are discussed.

Tactile Sensing—From Humans to Humanoids

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

/pdf/a-micro-electromagnetic-generator-for-vibration-energy-acpebp9i50.pdf

A micro electromagnetic generator for vibration energy harvesting

This paper presents the development of a vibration-induced power generator with total volume of ∼1 cm 3 which uses laser-micromachined springs to convert mechanical energy into useful electrical power by Faraday’s law of induction. The goal of this project is to create a minimally sized electric power generator capable of producing enough voltage to drive low-power ICs and/or microsensors for applications where ambient mechanical vibrations are present. Thus far, we have fabricated generators with total volume of 1 cm 3 that are capable of producing up to 4.4 V peak-to-peak, which have a maximum RMS power of ∼830 μW with loading resistance of 1000 Ω. The mechanical vibration required to generate this electrical energy has frequencies ranging from 60 to 110 Hz with ∼200 μm amplitude. The generator was shown to generate sufficient power at different resonating modes. We have demonstrated that this generator can drive an infrared (IR) transmitter to send 140 ms pulse trains every minute, and also a 914.8 MHz FM wireless temperature sensing system.

A laser-micromachined multi-modal resonating power transducer for wireless sensing systems

This paper presents the design, analysis, and experimental results of a vibration-induced power generator with total volume of -1 cm3 that uses laser-micromachined springs as resonating structures. The goal of our research is to create a minimally sized electric power generator capable of producing enough voltage to drive low-power IC circuit systems or micro sensors for robotic and automation applications where mechanical vibrations are present. Potential applications for the generator may also include mobile phone and heart-pacers where human motions can be used as a source of mechanical energy. Thus far, we have produced a generator capable of producing 2V DC with 64Hz input frequency with <200pm input vibration amplitude.

A Micromachined Vibration-Induced Power Generator For Low Power Sensors Of Robotic Systems

This paper presents the development of a vibration-induced power generator with total volume of ∼cm3 which uses laser-micromachined springs to convert mechanical energy into useful electrical power by Faraday’s Law of Induction. The goal of this project is to create a minimally sized electric power generator capable of producing enough voltage to drive low-power ICs and/or micro sensors for applications where ambient mechanical vibrations are present. Thus far, we have fabricated generators with total volume of 1cm3 that are capable of producing up to 4.4V peak-to-peak, which have a maximum rms power of ∼680µW with loading resistance of 1500Ω. The mechanical vibration required to generate this electrical energy has frequencies ranging from 60 to 110Hz with ∼200µm amplitude. We have demonstrated that this generator can drive an IR transmitter to send 140ms pulse trains every minute, or a 914.8MHz FM wireless temperature sensing system.

A Laser-micromachined Vibrational to Electrical Power Transducer for Wireless Sensing Systems

A novel solid propellant microthruster has been developed and used as the actuation assembly of a patented remote controlled capsule (RCC). It produces sufficient gas pressure to empty the drug reservoir within the RCC. A MEMS-based microigniter works as the critical component of the miniaturized thruster that houses the detonating agent – diazodintrophenol (DDNP) and the propellant – black powder. Ignition and combustion tests were performed to justify its feasibility and reliability. Results demonstrated that 166 mW power consumption led to one successful combustion and that complete and rapid drug release was achieved when the propellant ranged from 16 mg to 20 mg. The RCC integrated with the microthruster could provide a promising alternative for site-specific drug delivery in human GI tract.

A novel micro-fabricated thruster for drug release in remote controlled capsule

We report the development of a silicon integrated vacuum microelectronic tactile sensor array with on-chip signal readout circuits. Each sensing element in the 8×8 array consists of a field emission silicon cathode tip array located on the bottom of a micro-vacuum-cavity sealed with a thin elastic anode film on top. The sensor response is derived from constant bias emission current changes caused by tactile force induced variation of the anode-to-cathode separation. Each sensing element is connected to an on-chip integrated low power PMOS scanning read out driver. The integrated sensor array was fabricated using a combination of micro electromechanical systems (MEMS), microelectronics, and vacuum microelectronics techniques. The field emission tip array inside the sensing elements has an average tip diameter of 200 nm and density of up to 24,000 mm−2. The measured emission threshold voltage is 0.5–1.5 V and the reverse breakdown voltage of the device is >50 V. The prototype device was characterized in the pressure range of 0–150 kPa, in which the sensors exhibit a linear response with a mean sensitivity of ∼30.1 mV/kPa and a non-uniformity

Zhiyu Wen

Papers

A laser-micromachined multi-modal resonating power transducer for wireless sensing systems

A Micromachined Vibration-Induced Power Generator For Low Power Sensors Of Robotic Systems

A Laser-micromachined Vibrational to Electrical Power Transducer for Wireless Sensing Systems

A novel micro-fabricated thruster for drug release in remote controlled capsule

Development of an integrated vacuum microelectronic tactile sensor array