Composite-based piezoelectric devices are extensively studied to develop sustainable power supply and selfpowered devices owing to their excellent mechanical durability and output performance. In this study, we design a leadfree piezoelectric nanocomposite utilizing (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCTZ) nanomaterials for realizing highly flexible energy harvesters. To improve the output performance of the devices, we incorporate porous BCTZ nanowires (NWs) into the nanoparticle (NP)-based piezoelectric nanocomposite. BCTZ NPs and NWs are synthesized through the solidstate reaction and sol-gel-based electrospinning, respectively; subsequently, they are dispersed inside a polyimide matrix. The output performance of the energy harvesters is measured using an optimized measurement system during repetitive mechanical deformation by varying the composition of the NPs and NWs. A nanocomposite-based energy harvester with 4:1 weight ratio generates the maximum open-circuit voltage and short-circuit current of 0.83 V and 0.28 A, respectively. In this study, self-powered devices are constructed with enhanced output performance by using piezoelectric energy harvesting for application in flexible and wearable devices.

Piezoelectric technology, which converts mechanical energy into electrical energy, has recently attracted drawn considerable attention in the industry. Among the many kinds of piezoelectric materials, BaTiO3 nanotube arrays, which have outstanding uniformity and anisotropic orientation compared to nanowire-based arrays, can be fabricated using a simple synthesis process. In this study, we developed a flexible piezoelectric energy harvester (f-PEH) based on a composite film with PVDF-coated BaTiO3 nanotube arrays through sequential anodization and hydrothermal synthesis processes. The f-PEH fabricated using the piezoelectric composite film exhibited excellent piezoelectric performance and high flexibility compared to the previously reported BaTiO3 nanotube array-based energy harvester. These results demonstrate the possibility for widely application with high performance by our advanced f-PEH technique based on BaTiO3 nanotube arrays.

A flexible piezoelectric energy harvester(f-PEH) that converts tiny mechanical and vibrational energy resources into electric signals without any restraints is drawing attention as a self-powered source to operate flexible electronic systems. In particular, the nanocomposites-based f-PEHs fabricated by a simple and low-cost spin-coating method show a mechanically stable and high output performance compared to only piezoelectric polymers or perovskite thin films. Here, the non-piezoelectric polymer matrix of the nanocomposite-based f-PEH is replaced by a P(VDF-TrFE) piezoelectric polymer to improve the output performance generated from the f-PEH. The piezoelectric hybrid nanocomposite is produced by distributing the perovskite PZT nanoparticles inside the piezoelectric elastomer; subsequently, the piezoelectric hybrid material is spin-coated onto a thin metal substrate to achieve a nanocomposite-based f-PEH. A fabricated energy device after a two-step poling process shows a maximum output voltage of 9.4 V and a current of 160 nA under repeated mechanical bending. Finite element analysis(FEA) simulation results support the experimental results.

Piezoelectric harvester for road power generation was installed on test roads owned by Korea Highway Corporation. 24 harvesters were installed on the concrete pavement and the remaining 12 harvesters were installed on the asphalt pavement. After installation, power generation performance and environmental tests were carried out with three types of vehicles: compact / passenger cars / trucks. The running speed of the vehicle was 30 km/h, 60km/h, 90 km/h. The test results show that the larger the weight of the vehicle, the higher the power generation, the concrete road than the asphalt road, and the exposed type rather than the buried type. The generation amount according to the depth of buried was at least 2.2 times at the depth of 1cm than 5cm depth. When the delegator lighting test was performed using 12 harvesters, it was possible to light up more than 20 seconds in one vehicle due to the improvement of the charging circuit. In addition, the wireless communication module driving test enabled temperature sensing and data transmission for 25 seconds. In addition, there was no breakage of the pavement when driving more than 180 times, and the generation amount was maintained more than 90%. However, Test for the durability of the pavement and the self-durability of the harvester is required more than 180 times of vehicle driving conditions and required more than minimum of 6-12 months of long-term monitoring.

As the demand of fossil fuel has been increased, meeting future will be faced with exhausted non-renewable energy generation. In addition, there is a lot of expectation that fossil fuel resources are expected to get depleted in the end of century. Piezoelectric energy harvesting technology has significant advantages over other renewable energy sources such as solar panel, wind and geothermal energy. By using the pressure of vehicles, the piezoelectric energy transforms to electric energy by deformation of paving materials. There are many studies about this theme, only a few researches have been conducted on-site. It means that piezoelectric harvester is not available for roadway. Therefore, it is necessary to make it better a research framework that is available technology of piezoelectric materials and paving materials. The piezoelectric generator is tested before piezoelectric harvester manufacture for roadway. Each piezoelectric generator produces 9.38[mW/cm²] and piezoelectric harvester is manufactured by the number of 85 the piezoelectric generator. This harvester size has 50*20*9cm3 which is considered for wheel path of vehicle. When the chosen vehicle (about 2 ton) pass this harvester, the amount of electric energy is 255[W/m²] under 2[mm] of deformation and 30[km/h] of velocity. In this situation, the gathered energy is multiplied the maximum of voltage and electric current then divide it for the area of harvester. The test result is the temperature difference between the inside and outside after the thermal insulation coating process. When the external surface temperature is increased to 180 degrees, the internal temperature is kept 80 degrees even after about 30 minutes, indicating that the internal materials are protected from heat. In spite of many advantages with piezoelectric harvesting system, it is very hard to fit between roadway and harvester because of pavement damage. Most of paving material has a strong thickness. In this study, instead of asphalt and concrete pavement, the paving material is compound of poly-urethane to protect rutting and damage. To analysis for behavior, test is conducted by 90,000 times of wheel load on the pavement. The red line on the graph is commonly used asphalt pavement and the green one is polyurethane pavement. As it seemed that polyurethane pavement shows that the depth from wheel load is over 5 times better performance compared with asphalt pavement. Construction design is first of all, cutting off asphalt which is established before, then set up the tenth of piezoelectric harvesters, twenty fourth of road markers is installed into the roadway. Before filling up to space with polyurethane materials, wire arrangement and connect to controller. Each harvester is connected with controller that makes a signal for voltage, temperature sensor, water leak sensor. In order to use electric energy by harvester, road markers are selected, which each harvester has three of road markers. A circuit for lighting the light emitting device using the output of the harvester installed in the rest area was designed and manufactured. Basically, a circuit is configured to light up the harvester output, and a commercial power supply can be used in case the output of the harvester is reduced due to the durability thereof, and a controller is manufactured for each harvester to connect the road markers. Key Words: Piezoelectric Harvester

As most infrastructure have low natural frequency for vibration, an energy harvester to operate wireless sensors for them should be aimed to low frequency and have high output efficiency. This study proposes the energy harvester with parallel-connected single crystal ceramic for low frequency in order to gain enhanced efficiency. The performance is confirmed by the experiment using the acceleration data of hangers in Yeongjong Bridge.

Despite the fact that wireless sensor is needed to be activated in order to do efficient and continuous management, batteries are limited on their lives in case of wireless sensor. This paper suggests that the energy harvester model can be used within low frequency and examined using single crystal PMN-PT material which is definitely good at the efficiency of piezoelectric in order to maximize the output power. And the possibility of wireless sensor node power supply is verified by using an acceleration data of cable hangers of YoungJong Grand Bridge.