A Statically Balanced Compliant Ortho-Planar Mechanism for Low-Frequency Energy Harvesting

The usually high eigenfrequencies of miniaturized oscillators can be significantly lowered by reducing the stiffness through stiffness compensation. In this work, a mechanical design for a compliant ortho-planar mechanism is proposed in which the stiffness is compensated to such a degree that it can be identified as statically balanced. The...

Stiffness Compensation Through Matching Buckling Loads in a Compliant Four-Bar Mechanism

In this paper, a novel alternative method of stiffness compensation in buckled mechanisms is investigated. This method involves the use of critical load matching, i.e., matching the first two buckling loads of a mechanism. An analytical simply supported five-bar linkage model consisting of three rigid links, a prismatic slider joint, and four...

Tuning the Dynamics of Bistable Mechanisms by Introducing Travel Limits

Vibrations are a promising source for powering wireless sensors, for example in low-frequency environments like human motion. These environments suffer from unpredictable vibration spectra and their low-frequency and large amplitude characteristics offer great possibilities for mechanisms with double well potential energy characteristics. The...

Micro Energy Harvesting from Low-Frequency Vibrations: Towards Powering Pacemakers with Heartbeats

Miniaturized vibration energy harvesters can provide an alternative to batteries in powering the billions of low power devices we use today by extracting power from ambient motion. Especially for implanted medical devices, these alternative power sources may be an attractive option to overcome the limitations on longevity and the replacement...

Positive, negative or close to zero: Tuning the stiffness of compliant ortho-planar mechanisms.

Compliant ortho-planar mechanisms can be fabricated from a single sheet of material and they can move out of the plane in which they are fabricated. In this work, a design of such a mechanism is proposed in which stiffness compensation is applied. With a finite-element model, the force-deflection relation of the buckled mechanism was modelled...

A stiffness compensated piezoelectric energy harvester for low-frequency excitation

In this work, a stiffness compensated piezoelectric vibration energy harvester is modelled and tested for low-frequency excitations and large input amplitudes. Attracting magnets are used to introduce a negative stiffness that counteracts the stiffness of the piezoelectric beam. This results into a nearly statically balanced condition and...

Flexible piezoelectric AlN transducers buckled through package-induced preloading for mechanical energy harvesting

There is a high demand for novel flexible micro-devices for energy harvesting from low-frequency and random mechanical sources. The research of new functional designs is required to strategically enhance the performances and to increase the control on mechanical flexibility. In this work we report the fabrication and characterization of bi...

A method for tuning the stiffness of building blocks for statically balanced compliant ortho-planar mechanisms

In this paper a method is demonstrated for tuning the stiffness of building blocks for statically balanced compliant ortho-planar mechanisms. Three post-buckled mechanisms are proposed where the flexural rigidity can be manipulated over a part of their length in order to tune the ratio between the first two critical loads. A sensitivity...

A Rapidly Deployable Test Suite for Respiratory Protective Devices in the COVID-19 Pandemic

Introduction: The current COVID-19 pandemic has caused large shortages in personal protective equipment, leading to hospitals buying their supplies from alternative suppliers or even reusing single-use items. Equipment from these alternative sources first needs to be tested to ensure that they properly protect the clinicians that depend on...

Classifying miniaturised generators: State-of-the-art and future of vibration energy harvesting

Although motion energy harvesting at the small scales has been a research topic for over 20 years, the implementation of such generators remains limited in practice. One of the most important contributing factors here is the poor performance of these devices under low-frequency excitation. In this research, a classification of miniaturised...

On the efficiency of energy harvesters: A classification of dynamics in miniaturized generators under low-frequency excitation

Although motion energy harvesting at the small scales has been a research topic for over 20 years, the implementation of such generators remains limited in practice. One of the most important contributing factors here is the poor performance of these devices under low-frequency excitation. In this research, a new metric is proposed to...

Vibration Energy Harvesting from Human Motion: by Frequency up-conversion through Impact

Vibration Energy Harvesting has the potential to become a convenient, sustainable and localized power source for the billions of small electronic devices of the future. One of the most challenging areas within this field is the design of miniaturized generators for power harvesting from human motion. In this thesis, a new strategy, design and...