The process of acquiring the energy surround- ing a system and converting it into usable electrical energy is termed power harvesting. In the last few years, there has been a surge of research in the area of power harvesting. This increase in research has been brought on by the mod- ern advances in wireless technology and low-power electron- ics such as microelectromechanical systems. The advances have allowed numerous doors to open for power harvesting systems in practical real-world applications. The use of pie- zoelectric materials to capitalize on the ambient vibrations surrounding a system is one method that has seen a dramat- ic rise in use for power harvesting. Piezoelectric materials have a crystalline structure that provides them with the ability to transform mechanical strain energy into electrical charge and, vice versa, to convert an applied electrical potential into mechanical strain. This property provides these materials with the ability to absorb mechanical energy from their surround- ings, usually ambient vibration, and transform it into electrical energy that can be used to power other devices. While piezo- electric materials are the major method of harvesting energy, other methods do exist; for example, one of the conventional methods is the use of electromagnetic devices. In this paper we discuss the research that has been performed in the area of power harvesting and the future goals that must be achieved for power harvesting systems to find their way into everyday use. and replacement of the battery can become a tedious task. In the case of wireless sensors, these devices can be placed in very remote locations such as structural sensors on a bridge or global positioning system (GPS) tracking devices on ani- mals in the wild. When the battery is extinguished of all its power, the sensor must be retrieved and the battery re- placed. Because of the remote placement of these devices, obtaining the sensor simply to replace the battery can be- come a very expensive task or even impossible. For in- stance, in civil infrastructure applications it is often desirable to embed the sensor, making battery replacement unfeasible. If ambient energy in the surrounding medium could be ob- tained, then it could be used to replace or charge the battery. One method is to use piezoelectric materials to obtain ener- gy lost due to vibrations of the host structure. This captured energy could then be used to prolong the life of the power supply or in the ideal case provide endless energy for the electronic devices lifespan. For these reasons, the amount of research devoted to power harvesting has been rapidly in- creasing. In this paper we review and detail some of the top- ics in power harvesting that have been receiving the most research, including energy harvesting from mechanical vi- bration, biological systems, and the effects of power har- vesting on the vibration of a structure.

A Review of Power Harvesting from Vibration using

The process of acquiring the energy surrounding a system and converting it into usable electrical energy is termed power harvesting. In the last few years, there has been a surge of research in the area of power harvesting. This increase in research has been brought on by the modern advances in wireless technology and low-power electronics such as microelectromechanical systems. The advances have allowed numerous doors to open for power harvesting systems in practical real-world applications. The use of piezoelectric materials to capitalize on the ambient vibrations surrounding a system is one method that has seen a dramatic rise in use for power harvesting. Piezoelectric materials have a crystalline structure that provides them with the ability to transform mechanical strain energy into electrical charge and, vice versa, to convert an applied electrical potential into mechanical strain. This property provides these materials with the ability to absorb mechanical energy from their surroundings, usually ambient vibration, and transform it into electrical energy that can be used to power other devices. While piezoelectric materials are the major method of harvesting energy, other methods do exist; for example, one of the conventional methods is the use of electromagnetic devices. In this paper we discuss the research that has been performed in the area of power harvesting, and the future goals that must be achieved for power harvesting systems to find their way into everyday use.

A Review of Power Harvesting from Vibration using Piezoelectric Materials

A control circuit of a surgical device is disclosed. The control circuit includes a first circuit portion coupled to at least one switch operable between an open state and a closed state. The first circuit portion communicates with a surgical generator over a conductor pair to receive a control signal to determine a state of the at least one switch.

Surgical generator for ultrasonic and electrosurgical devices

A surgical instrument. The surgical instrument may comprise a transducer and an end effector. The transducer may be configured to provide vibrations along a longitudinal axis at a predetermined frequency and may comprise a piezoelectric stack positioned along the longitudinal axis. The transducer also may comprise a first metallic end mass positioned along the longitudinal axis adjacent a first end of the piezoelectric stack and a second metallic end mass positioned along the longitudinal axis adjacent a second end of the piezoelectric stack. The length of the transducer may be greater than or equal to of one wavelength and less than ½ of one wavelength. The end effector may be coupled to the transducer and may extend along the longitudinal axis. The length of the transducer and the end effector may be a multiple of ½ of one wavelength.

Ultrasonic surgical instruments

A surgical instrument for supplying energy to tissue may comprise a handle, a trigger, an electrical input, and a shaft extending from the handle. The surgical instrument may comprise and end effector first and second tissue engaging surfaces that are slanted with respect to a transection plane. The end effector may, for example, have an electrode defining a V-shaped cross sectional profile. The end effector may comprise a plurality of raised surfaces that are received by a plurality of indentions when the end effector is in the closed position. The end effector may comprise a cutting member having a plurality of bands. A surgical instrument for supplying energy to tissue may comprise a handle, a trigger, an electrical input, and a shaft extending from the handle. The surgical instrument may comprise an end effector. The end effector may comprise a cammed compression surface. The end effector may comprise an electrode comprising a tapered tissue contacting surface. Some surgical instruments may comprise an overload member.

Surgical instrument with jaw member

A piezoelectric ceramic transformer comprises a low impedance portion 11 including a plurality of piezoelectric ceramic layers 111 to 115 having different thicknesses, a high impedance portion 12 and internal electrodes 16. The low and high impedance portions 11 and 12 are subjected to a uniform polarization treatment in a thickness direction and with the same vector of polarization. The low impedance portion 11 includes one or more piezoelectric ceramic layers having a thickness different from those of the other layers therein. No delamination of electrodes or breaking of ceramics occur upon polarization treatment. Therefore, a compact piezoelectric ceramic transformer for power source which has a high mechanical quality coefficient Qm and a high electric power transmission efficiency is provided.

Piezoelectric ceramic transformer being driven with thickness extensional vibration

Piezoelectric actuator (60) is equipped with a piezoelectric element (10) that expands and contracts according to the state of an electric field, a pedestal (20), a vibration film (30), and a support member (40). A reinforcement member (50) is arranged in a region which acts as a node for divided vibration by piezoelectric element (10), in the divided vibration mode that occurs in high-frequency bands. One or more reinforcement members (50) are selectively arranged on the front or back of the piezoelectric element (10). Since the vibration mode of piezoelectric element (10) can be changed with this configuration, divided vibration, which is a source of hills and valleys (peaks and dips) in frequency acoustic pressure level characteristics, can be efficiently suppressed. Therefore, it is possible to realize flat frequency acoustic pressure level characteristics and reproduce high-quality sound.

Piezoelectric actuator and electronic device

A new kind of multilayer piezoelectric ceramic transformer for switching regulated power supplies is described. This transformer operates in the second thickness extensional vibration mode. Its resonant frequency is higher than 1 MHz. Theoretical calculations are implemented using a distributed constant electromechanical equivalent circuit method. It is calculated that this transformer can operate with higher than 90% efficiency. A fabricated transformer is examined. PbTiO/sub 3/ family ceramics are used because of the large anisotropy between electromechanical coupling factors. Results indicate that the piezoelectric transformer has good resonant characteristics, with little spurious vibration, and exhibits 16 W/cm/sup 3/ power density with high efficiency at 2 MHz. A switching regulated power supply, applying the piezoelectric transformer, is built and examined. >

Piezoelectric ceramic transformer operating in thickness extensional vibration mode for power supply

A power converter with a new piezoelectric transformer is presented. The piezoelectric transformer, made of lead titanate solid solution ceramic, is operated with a thickness extensional vibration mode. This transformer can operate at high frequency, over several megahertz, with about 90% efficiency. The resonant frequency for the transformer is 2 MHz. The power converter with the transformer applies the theory for a class-E switching converter using an electromagnetic transformer. Maximum output power is obtained when the switching frequency is slightly higher than the resonant frequency. A 4.4 W output power is successfully obtained with 52% efficiency at 2.1 MHz switching frequency.<<ETX>>

2 MHz Power Converter with Piezoelectric Ceramic Transformer

Vibration-level characteristics of electromechanical properties in the pseudo-ternary solid solution system PbZrO3-PbTiO3-Pb(Mn1/3Sb2/3)O3 ceramics were studied using a constant current control method. Stability under a vibration-level change was determined from the measurements of Young's modulus Y0 E and mechanical dissipation factor Q m-1. Durability degree for a high vibration-level excitation was estimated by a heat generation phenomenon. The durability was found to be dependent on the stability. As the stability increased, the durability also increased. The durability degree for a high vibration-level excitation was improved in the pseudo-ternary solid solution system PbZrO3-PbTiO3-Pb(Mn1/3Sb2/3)O3 ceramics over the binary solid solution system PbZrO3-PbTiO3 ceramics.

https://iopscience.iop.org/article/10.1143/JJAP.34.5328/pdf

Yasuhiro Sasaki

Papers

Piezoelectric ceramic transformer being driven with thickness extensional vibration

Piezoelectric actuator and electronic device

Piezoelectric ceramic transformer operating in thickness extensional vibration mode for power supply

2 MHz Power Converter with Piezoelectric Ceramic Transformer

Stability of PbZrO 3-PbTiO 3-Pb(Mn 1/3Sb 2/3)O 3 Piezoelectric Ceramics under Vibration-Level Change