Collecting energy from impact and vibration
Researchers are working on systems that will allow energy harvesters to generate electricity from the mechanical vibrations of a wide range of sources.
Assistant Professor Sherry Towfighian from the Mechanical Engineering Department at Binghamton University has been working on a way to increase the conversion rate of a sustainable, low-cost and widely available form of mechanical energy using phenomena called piezoelectricity and triboelectricity.
Piezoelectric energy comes from converting tension to electricity, while triboelectric energy comes from converting friction to electricity – like the energy created when you rub a balloon on your hair or shuffle your feet on the carpet.
Triboelectricity, in particular, has received more attention in recent years as a fully sustainable, green form of energy. Things like triboelectric toys have been created to replace battery-powered ones and some researchers have been working on devices that can charge with the swipe of a finger.
However, converting tension and friction to energy can be difficult at low frequencies or with certain types of movements. In two separate studies, Towfighian has been improving the conversion efficiency of energy harvesters and has expanded to the ability to collect energy from a sudden impact.
Low-frequency vibrations
In a study with graduate student Wei Yang from Binghamton University, Towfighian found a way to collect low frequencies with a piezoelectric energy harvester.
The study titled “Low frequency energy harvesting with a variable potential function under random vibration” was published in Smart Materials and Structures on June 11, 2018.
Towfighian explained the importance of the study saying, “Typically, traditional energy harvests can only harvest energy from a certain range. For instance, a conventional energy harvester on a train can only cover 20 percent of the mechanical vibration energy. Our study increases the range of energy harvesters so that more energy can be collected and converted to electricity.”
Impact vibrations
A related study from Towfighian titled “Experimental and theoretical investigation of an impact vibration harvesters with triboelectric transduction” was published in the Journal of Sound and Vibration in November 2017.
“The study looked at how we could collect the energy from a sudden impact and use that to power a sensor,” she explained.
“For instance, if there’s a car crash, we could collect the energy from the impact of the two cars to power a sensor that calls the paramedics. The same could be true for elderly people who fall. Sensors powered by impact could allow them to get the help they need quickly.”
Towfighian worked with graduate students Alwathiqbellah Ibrahim from Binghamton University and Abdallah Ramini from Gannon University.
While the technology is still experimental, the study opens the door to more possibilities for impact-based energy harvesting.
Both studies will help researchers make vibration energy harvesting more effective and more accessible as a low-cost, sustainable energy source for self-powered wireless sensors used for health monitoring of transportation vehicles, structures and people.