The hottest piezoelectric power generation technol

Piezoelectric power generation technology is gradually approaching

humans who are used to consuming energy every day can also become generators that can provide energy sustainably

Li Yongxiang: researcher of Shanghai Institute of silicate, Chinese Academy of Sciences, majoring in inorganic functional materials and devices

accustomed to consuming energy every day, have you ever thought of turning into an automatic generator that can provide sustainable energy

this is no joke. Using piezoelectric power generation technology, researchers are trying to make it a reality

transform the ubiquitous mechanical vibration energy into electrical energy

in fact, energy is everywhere. We run, jump, walk and move every day, constantly generating mechanical vibration energy. Piezoelectric power generation technology aims at these inconspicuous energy and collects it for effective use

of course, human power generation is far from covering all the technologies of piezoelectric power generation

when it comes to piezoelectric power generation technology, we first go back to 1880. Curie brothers found in quartz crystal that when the crystal is subjected to mechanical stress, its surface will generate electric charge; On the contrary, when an electric field is applied to the crystal, the crystal will deform. The former is named as positive piezoelectric effect, and the one with increasing effect in order is called inverse piezoelectric effect

over the past 100 years, piezoelectricity and piezoelectric materials have gone through the development of quartz crystals, barium titanate ceramics, lead zirconate titanate ceramics, relaxor ferroelectric single crystals and other milestones. Various piezoelectric sensors, transducers and drivers have become irreplaceable important devices in the technical fields of underwater sound, ultrasound, laser, infrared, electro-optic and so on

in recent years, the contradiction between the soaring demand for energy in industrialized society and the limited supply of fossil energy has become increasingly prominent. Countries have made great efforts to develop all kinds of renewable energy, and energy recovery technology has become a research and development hotspot. Piezoelectric power generation is such a technology, which uses the positive piezoelectric effect of piezoelectric materials to convert mechanical vibration energy into electrical energy, so as to collect vibration energy in the form of human walking, mechanical vibration, and even noise, and apply it to life through energy conversion, rectification, storage, power supply and many other links

this energy collection system helps us use the energy that has been wasted. In the near future, stations, highways, tracks and daily mats, carpets, floors, schoolbags, shoes, clothes, etc. may become power generation devices as a supplement to many other energy sources

piezoelectric power generation has the advantages of simple structure, no heating, no electromagnetic interference, no pollution and easy to realize miniaturization and integration. It has become one of the current research hotspots because it can meet the power demand of low energy consumption products

power generation floors, power generation roads, power generation bags and other developed countries such as Japan, the United States and Europe have studied the self-service power supply system of piezoelectric power generation for many years and made good progress, especially Japan is in the forefront of the world in terms of application

from 2006 to 2009, East Japan Passenger Railway Co., Ltd. conducted three tests of power generation floor at Tokyo railway station, with the goal of generating power that can make 100 watt bulbs glow for 0.1 seconds when passengers pass through automatic ticket gates

at the 2010 Shanghai WorldExpo, the Japan Pavilion displayed a piezoelectric floor, and visitors could light up the lights with a few steps, which surprised many people

it is also reported that NEC and other companies in Japan have jointly developed a new type of light-emitting road signs. Piezoelectric power generation devices are buried under the road to drive LED light-emitting signs, basically reaching the practical level of self power supply

similarly, the Israel Institute of technology has also implanted a large number of piezoelectric crystals in the asphalt of ordinary roads to generate electricity through piezoelectric conversion when cars drive by. It is estimated that one kilometer of road surface can generate about 100 ~ 400 kW of electricity. Theoretically, these piezoelectric materials implanted with asphalt can be used for at least 30 years and can be used in any large flow road, including railway and highway. At present, Israel has only carried out small-scale experiments on this technology, and will carry out large-scale experiments in the future

in terms of key preparation of carbon fiber precursor, auxiliary materials such as sizing agent and spinning technology, it is still subject to imported products

in addition, in order to improve the efficiency of energy acquisition, R & D personnel generally collect and utilize piezoelectric, thermoelectric, photovoltaic and other energy at the same time in design. For example, the US military is developing a device for soldiers to generate electricity while marching. Soldiers can provide self-service power to their electronic devices, so that they do not have to carry energy storage batteries weighing up to 10 kg, which greatly reduces the marching load

recently, it was also reported that a California congressman proposed a new bill to use piezoelectric power generation technology on the road, saying that the annual power generation is enough to supply more than 30000 households. Whether his proposal is feasible and effective remains to be seen. To infer the maximum temperature that the material can withstand in 100000 hours

relevant research institutions in China are also actively carrying out research on energy recovery. At the upcoming National Science and technology week in Shanghai, the Shanghai Silicate Institute of the Chinese Academy of Sciences plans to demonstrate its own piezoelectric power generation device to the public on Nanjing Road

there is no essential difference in the basic principles of the above different research and development work. The main difference lies in the different working modes of piezoelectric materials and the different structures of systems and applications

at present, PZT-5H piezoelectric ceramics are mostly used as piezoelectric transducers, and the structural shapes include ceramic sheets, ceramic cantilever beams, piezoelectric drums, piezoelectric cymbals and multilayer ceramic structures. A single piezoelectric power generation unit can generally output a voltage of 5 ~ 20 volts, a current of milliampere level, and a power of tens of milliwatts level, which can meet the energy supply needs of low-energy electronic products such as network sensors. In order to increase the generating power, multiple components must be connected in parallel to increase the output current of the device

nano generator that can generate electricity as long as it moves

in recent years, piezoelectric materials are also developing to a more microscopic scale. Nano piezoelectronics combines semiconductors and piezoelectricity, which is expected to develop new piezoelectric field effect transistors, self powered nano generators, wireless nano medicine and biological devices

scientists in the United States and China have jointly studied and reported a piezoelectric nano generator, which is based on zinc oxide nanowires and realizes the conversion of mechanical energy into electrical energy at the nano scale

the diameter of nanowires is generally less than 100 nm, but its length can reach several microns. Such a large aspect ratio enables a very small force to bend the nanowires and produce a potential difference. This means that as long as you move, you can generate electricity without walking. Weak muscle movement can also drive nano generators

it is reported that the theoretical power generation efficiency of the nano generator can reach 17% - 30%, which has high energy density and conversion efficiency, and is easy to realize real miniaturization, which opens up a technical route for power generation in vivo by using human motion

in addition, in 2009, scientists from Samsung Integrated Technology Research Institute in South Korea reported on advanced materials that they had prepared zinc oxide arrays on flexible substrates, and a large number of zinc oxide nanorods were connected in parallel to obtain a current density of 1 mA/cm2, which can be used for force sensors, touch screens and artificial skin sensors

however, although people have been able to synthesize a large number of ZnO nanorod arrays with controllable purity, size, morphology and crystal structure, there are still many challenges in how to convert natural mechanical energy such as motion, vibration and fluid into electrical energy, so as to realize nano devices without external power supply

solving the problem of cost and benefit is the key

at present, the current generated by the external vibration mechanical energy through the energy collection device is AC, and its disadvantage is discontinuous and irregular. In engineering applications, corresponding matching circuits must be designed, and bridge rectifier circuits must be used to convert alternating current into direct current, store the generated electric energy, and supply external loads after a certain amount of charging for a certain time

the key technologies of the energy recovery system mainly include the selection of piezoelectric materials, the design of piezoelectric vibrators with similar external vibration frequencies and their support methods, and the design of efficient electric energy collection and storage circuit systems

current confirmatory demonstrations mainly drive some lighting or displays. There should be no technical obstacles to a large amount of power generation, mainly the cost and benefit. How to further improve the efficiency of power generation, significantly reduce costs, and improve the reliability and durability of the system are very important problems

the author predicts that if scientific research institutions, enterprises and the government work together, piezoelectric power generation technology is expected to be gradually promoted and applied within 10 years