Piezo electric energy harvesting system for biomedical applications

Abstract

Emerging technology in semiconductor devices and circuits has enabled ultra-low power systems in medical, smart structures, and hard to reach places which fueled the energy scavenging research. Energy harvesting is an important enabling technology necessary to unleash the next electronic revolution and Internet of Things. Human body-based vibration energy harvesting has been of recent interest in powering biomedical electronics for its almost universal availability. Our research focuses on harvesting vibration energy generated from human body movement using PE energy harvester. To harvest energy, special interface circuit is needed to extract maximum power available from the harvester. The first part of this thesis presents a survey about state-of-the-art solutions in energy harvesting methods using vibrational harvesters, commonly used PE harvester interface circuit, and wireless energy transfer methods. It presents a study of PE harvester and its suitability for low-power applications. Furthermore, trade-offs among common interface circuit topologies used in PE-based harvesting applications is presented. Moreover, this part presents measured data reported in the literature, and collected from off-the-shelf PE harvesters adjusted for industrial or laboratory-setting environment. The second part focuses on harvesting vibration energy from human body movement using the PE harvester. Contemporary research revealed that most of the published data, including harvesters’ datasheets, are adjusted for industrial or lab-setting environment. This part presents experimental data obtained from the human body using off-the-shelf harvesters, and discrete electrical components. Our experimental results showed that 0.5 cm3 PE harvester can generate up to 7.4 µW/cm3 . The final part of the thesis deals with optimizing, simulating, and testing AC-DC converters suitable for start-up and continuous mode operations of portable biomedical electronics. These circuits include Voltage Doubler and Bias-Flip rectifier which are designed in 65 nm CMOS process. Further, it compares between two Voltage Doubler circuits, one of them is constructed using discrete components and the other one fabricated on-chip. Experimental results showed that on-chip VD is more efficient than off-chip VD by 11%. Moreover, maximum extracted power from on-chip VD is 83 nW at 0.21 g.

Date of Award	2015
Original language	American English
Supervisor	Baker Mohammad (Supervisor)