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The power generated by the designed piezoelectric energy harvester replaces the standby power that is constantly used in sensors and driving circuits in commercial LED shoes; the harvester thus reduces battery consumption. LED shoes incorporating a piezoelectric energy harvester are designed for night workers who work near roads. The piezoelectric energy harvester, composed of a piezoelectric device (PZT ceramic), which is inserted under the insoles of shoes, converts mechanical energy generated by motion of user into electrical energy. The designed harvester has an area of 6 × 4 mm and height of 3 mm (pressed state); it weighs 14 g. Because of its small size and light weight, device is suitable for real workers’ shoes. This piezoelectric energy harvester produces 800 μW at a resistive matching point of 400 kΩ; it is used as a sensor to control an LED switching circuit, allowing the LEDs to blink based on user movements. By applying the piezoelectric energy harvester to LED shoes, battery usage time can be doubled compared to LED shoes that are turned on continuously.

A self-powered energy harvester for real roads to predict and detect black ice formation and pinpoint dangerous road sections was developed. An open-type piezoelectric device was developed for a high-efficiency module to achieve uniform stress distribution for enhanced energy harvesting performance by free-fixed-end type central strike mechanism. The output performance of the open-type device was 80% higher than that of the closed-type device. A uniform stress distribution road piezoelectric generator (URPG) with 120 open-type devices was installed on real roads. The URPG showed output power performance of up to 2.38 mW/cm3 when a vehicle passed once under the condition of being buried 2.5 cm below the road surface. The URPG can operate a wireless temperature sensor monitoring system for 83 s and charge a cellphone battery for 53 s. The developed self-powered energy harvesters can be used to reduce accidents caused by black ice on real roads.

To meet the increasing demand for electric vehicles, this paper presents a novel concept to enhance the energy generation performance of piezoelectric energy harvesters used as charging stations on roads. A lever-type piezoelectric energy harvester with a deformation-guiding mechanism was designed and fabricated to overcome the existing limitations of low electrical output and low durability of piezoelectricity under extremely low road displacement conditions of 1 mm. The proposed harvester achieved a maximum output power of 60.3 mW at a load resistance of 50 kΩ under an input displacement of 1 mm. Thus, the module’s electrical performance was significantly higher than that obtained in previous similar studies. The proposed harvester had 467% higher output power than the previously proposed vibration type road energy harvester. For the energy storage test, a 0.08 F supercapacitor was charged up to 5.09 V (1 J) in 170 min. The results prove that the energy generated by the proposed harvester can be potentially used as a power source for electric vehicles on smart roads beyond the power supply of various sensor systems on the road.