Session 8

SESSION 8

Unfortunately, i couldn't make it for TWC class this week. I wasn't feeling very well. In lieu of my usual post about the week's session, i've decided to review an article which ties in with this week's topic - Energy and World Change (Past, Present,and Future)

The article that i've chosen is Tiny Generators Produce Electricity from Ambient Vibrations

Brief Overview/Summary

In a study funded by the National Science Foundation, Sandia National Laboratories, and the National Institute of Standards and Technology, scientists at the University of Michigan have developed mini-generators that have the ability to produce enough electricity to power small electrical devices such as wristwatches, pacemakers or wireless sensors. According to the article, these mini-generators are "highly efficient at providing renewable electrical power from arbitrary, non-periodic vibrations." What exactly are "arbitrary, non-periodic vibrations"? These vibrations include vibrations caused by human movement, vibrations from cars travelling along a road, vibrations from machinery like washing machines, industrial machines, etc....

The researchers at the University of Michigan have managed to build 3 protoypes and are currently working on a fourth generator. 2 of these generators perform energy conversion through Electromagnetic Induction, which is how large scale electricity generation is performed in many power plants today.

The team's 4th prototype, currently still under development, measures only 1 cubic centimeter. It's construction is based on Piezoelectric Material that generates electricity when stress is applied. Possible applications for this prototype are infrastructure health monitoring. The researchers hope that one day, these PFIGs will be able to power bridge monitoring sensors that detect cracks and other structural problems long before it becomes a major problem.

The 3 existing generators have been been able to produce up to 500 microwatts of electricity from typical vibrations found on the human body. To provide perspective, a wristwatch only requires between 1-10 microwatts, or a pacemaker, which requires 10-50 microwatts. Clearly, the energy produced by the PFIG is more than enough to power many low-energy devices available today.
(Can you imagine a wristwatch with a battery that never needs to be replaced?)

Key Takeaways

According to Professor Najafi, these PFIGs are different from existing generators that rely on vibrations from the surrounding environment because these existing devices rely on regular and predictable energy sources. "The vast majority of environmental kinetic energy surrounding us everyday does not occur in periodic, repeatable patterns. Energy from traffic on a busy street or bridge.....for example, cause vibrations that are non-periodic and occur at low frequencies," says Najafi. He continues on to elaborate that "our parametric generators are more efficient in these environments."

Galchev, one of the other researchers, explains that the ultimate goal of this research project is to "enable various applications like remote wireless sensors and surgically implanted medical devices. These are long lifetime applications where it is very costly to replace depleted batteries or, worse, to have to wire the sensors to a power source." In other words, the researchers hope to be able to use these PFIGs in devices such as pacemakers and various monitoring sensors like temperature sensors, and stress sensors. Applying PFIG technology in pacemaker technology has the potential to create a pacemaker that will outlast the life of the user! The thought that immediately comes to mind is that of Tony Stark, from the recent Ironman Movie, who requires a device implanted in his chest to keep him alive. In the beginning of the movie, his device is powered by a cumbersome car battery. However, Tony Stark, being a genius, manages to create a self powered device with the ability to generate energy far greater than what is really needed.

Current batteries are still cumbersome and often a tradeoff between battery size and capacity is required. According to Professor Najafi, "There is a fundamental question that needs to be answered about how to power wireless electronic devices, which are becoming ubiquitous and at the same time very efficient. There is plenty of energy surrounding these systems in the form of vibrations, heat, solar and wind." Utilizing the power of energy-scavenging, batteries to power these small devices would not need to have large capacities, allowing for cheaper, and better production of wireless sensors.

Issues for Further Discussion

Although the PFIGs are still in their infancy, i really do hope to see this new emerging technology being applied in the near future. My issues for discussion are:

1. Other than what has already been listed, what other currently existing technology may be synergized with this emerging technology to create even more exciting possibilities?
2. If this technology becomes so efficient that significant amounts of electricity can be generated, might PFIGs be used as large scale alternative electricity generation, similar to wind farms and solar plants today?

Personal Ratings

(8/10) I found this article to be very interesting. The idea of having batteries that recharge on their own is really exciting! I can't wait to see this emerging technology get past it's infancy and make its way down to consumers.