low-power step-up circuits for energy harvesting

Abstract

Due to the significant growth of the Internet of Things (IoT), wearable devices and low-power sensors are experiencing exponential demand across various applications, ranging from environmental monitoring to the healthcare and wellness sectors. The demand for self-powered devices and sensors, along with the need for cheaper, faster, and more sustainable fabrication methods, is rising. To tackle these challenges, the current research on printed electronics paves the way for the design of low-cost and flexible devices for harvesting applications, becoming a key enabling technology to develop new applications. The primary way to obtain self-powered devices is to focus on energy harvesting through sustainable power sources, like thermoelectric, solar, vibrations, RF, triboelectric, etc. In sufficiently low-power applications, these energy sources may even eliminate the need for batteries, reducing even more fabrication costs and pollution. In this thesis work, the process of designing an energy harvester that can power a real-life application is explored, as well as the challenges and benefits of using flexible hybrid electronics for this task. The process is addressed holistically, from the introduction of thermoelectric generators, to the DC-DC converters and startup circuits that conform the core of the harvester circuit. Consequently, this thesis work presents the design and optimization of a flexible environmental sensing circuit using flexible hybrid electronics. Furthermore, it presents a novel self-powered oscillator topology, with a startup voltage lower than 10mV and a conversion ratio on-par with the state of the art, which can be used as a startup stage for more efficient circuits. Additionally, this work introduces a novel DC-DC converter topology, designed to integrate the oscillator circuit as its startup stage, with a startup voltage around 100mV and the implementation of a Maximum Power Point Tracking (MPPT) method for greater efficiency, improving over the startup voltage of commercial alternatives. In conclusion, in this thesis work, novel topological designs for low-power energy harvesting based in Thermoelectric Generators (TEGs) were accomplished. The results evidence the importance of a holistic approach from electronic design to manufacturing and validation setups, to build reliable and efficient TEG based systems, which is crucial for their adoption in real applications.

Date of Award	14 Nov 2024
Original language	English
Supervisor	Ana Moya Lara (Director) & Claudia Custodia Delgado Simao (Director)