The development of three energy conversion devices that are able to transform vibrations in their surroundings to electrical energy is discussed in this thesis. These energy harvesters are based upon a newly invented architecture called the Parametric Frequency Increased Generator (PFIG). The PFIG structure is designed to efficiently convert low frequency and non-periodic vibrations into electrical power. The three PFIG devices have a combined operating range covering two orders of magnitude in acceleration (0.54–19.6m/s ²) and a frequency range spanning up to 60Hz; making them some of the most versatile generators in existence.

The PFIG utilizes a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromechanical scavenger. By up-converting the ambient vibration frequency to a higher internal operation frequency, the PFIG achieves better electromechanical coupling. The fixed internal displacement and dynamics of the PFIG allow it to operate more efficiently than resonant generators when the ambient vibration amplitude is higher than the internal displacement limit of the device. The PFIG structure is capable of efficiently converting mechanical vibrations with variable characteristics including amplitude and frequency, into electrical power.

The first electromagnetic harvester can generate a peak power of 163µW and an average power of 13.6µW from an input acceleration of 9.8m/s ² at 10Hz, and it can operate up to 60Hz. The internal volume of the generator is 2.12cm³ (3.75 including casing). It sets the state-of-the-art in efficiency in the <20Hz range. The volume figure of merit is 0.068%, which is a 10x improvement over other published works. It has a record high bandwidth figure of merit (0.375%). A second piezoelectric implementation generates 3.25µW of average power under the same excitation conditions, while the volume of the generator is halved (1.2cm³).

A third PFIG was developed for critical infrastructure monitoring applications. It is used to harvest the very low-amplitude, low-frequency, and non-periodic vibrations present on bridges. The device generates 2.3µW of average power from an input acceleration of 0.54m/s² at only 2Hz. The internal volume of the generator is 43cm³. It can operate over an unprecedentedly large acceleration (0.54–9.8m/s²) and frequency range (up to 30Hz) without any modifications or tuning.