## 2 Design of the Energy Harvester
### Power-Generation Bicycle Lane Using Piezolectric Material Conceptual  
Bicycle-pedestrian surfaces can be composed of a diverse selection of materials. Regarding piezoelectric materials, PZT-type materials, which feature a high energy conversion capability but are still ceramic, are used. Such materials are brittle and can be damaged easily [52; 53]. Therefore, selecting the appropriate materials for energy transfer is essential. Ethylene propylene diene monomer (EPDM) [64], which has a smooth surface, resists high impacts and temperatures and is also flexible, durable, and non-polluting. Hence, it was selected as the synthetic rubber flooring material. The designed dimensions per sheet were 50 cm \(\times\) 50 cm \(\times\) 25 mm. The piezoelectric device was sandwiched between two rubber sheets with a gap drilled to install the vibration enhancement spring, as shown in Figure 8. \begin{table}
\begin{tabular}{c c} \hline \hline
**Number of Mechanically Applied** & **Charging Time(s)** \\
**Preliminary Test Kit (Sets)** & **Charging Time(s)** \\ \hline
1 & 3.50 \\ \hline
2 & 1.75 \\ \hline
3 & 0.88 \\ \hline
4 & 0.44 \\ \hline
5 & 0.22 \\ \hline
6 & 0.11 \\ \hline
7 & 0.05 \\ \hline
8 & 0.03 \\ \hline
9 & 0.02 \\ \hline
10 & 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Charging time needed for a preliminary test kit to generate energy when subjected to mechanical force. Figure 7: Trial installation area for preliminary test kit. The significant parameters that affect the conversion of mechanical energy into electricity are listed in Table 3.  
Owing to their electrical characteristics, piezoelectric devices harvest electricity at high voltages and low currents. The voltage and current obtained from one piezoelectric sheet were approximately 10-15 V and 70-110 \(\upmu\)A, respectively. However, using an efficient energy harvesting circuit can yield additional power. In the experiment, eight piezoelectric modules were connected in parallel along the intended bike path to maximize the energy produced within an area of 0.25 m\({}^{2}\); the system generated a power of approximately 1 W. When force was exerted on one piezoelectric sheet through the synthetic rubber sheet, over ten iterations, the average voltage received per load was 15.8 V, and the average current was 7.2 \(\upmu\)A. Subsequently, a direct force was employed in the experiment, with springs placed under the piezoelectric modules such that the maximum displacement of the piezoelectric tip did not exceed the yield strength of the material; this helped prevent any damage and extend the period of continuous vibrations. The dimensions and mechanical characteristics of the spring influenced its natural frequency. When the spring was subjected to an excited frequency close to its natural frequency, the spring resonated; this resulted in vigorous and continuous oscillations of the piezoelectric tip, thereby producing the highest energy output. The piezoelectric sheet was overlaid with an EPDM synthetic rubber sheet to protect the piezoelectric modules from damage resulting from direct contact with the external forces. The actual piezoelectric energy harvesting circuit and the voltage signal captured from the oscilloscope are presented in Figures 9 and 10, respectively. Figure 8: The material used and the piezoelectric installation area: (**a**) piezoelectric module installation; (**b**) surface material for bike lane.