This thesis presents the design and evaluation of a low-power wireless sensor system intended to operate in conjunction with a vibrational piezoelectric energy harvester and a power conditioning circuit inside a plane wing. The system was tested in a controlled laboratory environment under various configurations, including different transmission modes, power levels, and sampling frequencies, to assess its performance, energy efficiency, and stability. Key findings indicate that sampling frequency significantly influences measurement stability. Continuous transmission mode, where data is sent without delay, while offering high temporal resolution, introduced greater variability in temperature readings, likely due to environmental noise and power supply fluctuations. In contrast, burst mode, which only sends 3 measurements in quick succession, achieves a better balance between resolution and stability, suggesting that incorporating intentional delays can mitigate noise sensitivity. Thermal recovery tests revealed that sampling density affects response time, with delayed mode showing slower returns to baseline, possibly due to self-heating or insufficient data resolution. An attempt to implement a low-power sleep mode revealed that actual current consumption did not decrease as expected, indicating an incomplete power-down mode and highlighting the need for further investigation into power management. The power consumption study confirmed that oscillator frequency and transmission power significantly affect current draw, although an anomaly observed at 4 MHz in delayed mode suggests potential efficiency zones in the transceiver’s operation. Integration with the energy harvester demonstrated the system’s ability to function under energy-constrained conditions. Testing with different storage capacitors showed that a 680 𝜇F capacitor provided the best balance between data transmission quality and energy availability. These results highlight trade-offs between energy storage capacity and responsiveness, and emphasize the importance of hardware optimization in energy-autonomous sensor systems.

Piezoelectric Energy Harvesting (PEH) offers a viable and sustainable solution for powering low-power electronic systems in hard-to-reach or maintenance-intensive environments, such as those found in aviation. The focus of this thesis lies on the circuit design aspect of the system, encompassing harvesting efficiency, regulation, and adaptive switching logic. The results validate that the proposed design fulfills the energy demands of a low-power wireless sensor, even under irregular excitation patterns. A range of advanced rectifierless interface topologies are investigated, including Rectifierless Synchronous Electric Charge Extraction (ReL-SECE), Rectifierless Synchronized Switch Harvesting on Inductor (ReL-SSHI), and Parallel-SSHI (P-SSHI). These non-linear techniques are selected for their ability to maximize power output, eliminate diode thresholds, and dynamically adapt to varying load and vibration conditions, significantly improving power transfer compared to traditional full-bridge rectifiers. Energy storage is realized through the use capacitors due to their rapid charge/discharge characteristics and long operational life. To ensure circuit safety and longevity, an over-voltage protection mechanism is implemented using a shunt regulator in combination with a resistive voltage divider. Additionally, a dedicated voltage regulation stage is incorporated to maintain a stable 3.3 V DC output, necessary for reliable operation of downstream wireless transmitters and onboard sensor systems. The proposed system is designed to be energy-autonomous, capable of cold-start operation, and optimized for long-term deployment without the need for external maintenance or battery replacement. The approach aligns with current trends in micro-energy harvesting (MEH) for IoT applications, emphasizing compactness, adaptability, and robustness under real-world conditions. Overall, the system demonstrates the practical potential of intelligent, self-powered harvesting circuits in enabling sustainable sensor networks and instrumentation in modern aircraft environments.

With the development of the Internet of Things (IoT) and biomedical technologies, the utilization of wearable devices has become an emerging trend, attracting attention to the powering solutions for these devices. Thermoelectric energy harvesting (TEH) is suitable for converting the temperature difference in the ambient environment to power wearable devices and IoT sensors. However, the DC voltage converted by the thermoelectric generator (TEG) still requires an energy harvesting interface, normally a DC-DC interface to provide the regulated power to the load. Consequently, the features of the TEG impose challenges to the implementation of the DC-DC interface. Due to the temperature dependency of the TEG, the DC-DC interface applied to the TEH system should be able to cope with the dual-polarity input voltage and be capable of achieving a high power conversion efficiency for a wide range of voltage conversion ratios.