Power Potent Piezoelectric Packs
Backpack Strap Friction Produces Electrical Energy
Scientific advances lead to effortless production of electrical energy which can be used to power small devices in the wilderness.
Mechanical engineers from Michigan Technological University and Arizona State University, teaming with Blacksburg, Virginia company NanoSonic, have designed backpack straps that will convert the action of the straps rubbing on shoulders and backs into electrical energy that can power or recharge portable electronic devices in the wilderness, where power may be in short supply or even non-existent.
The straps, made of a piezoelectric material with specially constructed electrodes embedded within, take the otherwise wasted ambient energy that is produced by the friction of the straps rubbing on shoulders and essentially performs an "energy harvest" effect.
Mechanical engineers Jonathan Granstrom and Joel Feenstra from Michigan Technological University, Henry Sodano from Arizona State University, and Kevin Farinholt from NanoSonic, Inc., recently published their results in an issue of Smart Materials and Structures.
For hikers, backpackers and campers, this means being able to generate power for short-term usage or accumulating it for later use in an environment where power is not available, simply by performing an action that they would anyway in the normal course of an outdoor activity; walking with a backpack on their shoulders.
"The advantage of this system is that it seamlessly replaces a currently-used material with one that generates electrical energy," Sodano told PhysOrg.com. "The strap would operate no differently than the strap on a traditional backpack."
The backpack uses straps made of a strong, flexible material that feels very similar to nylon. But unlike nylon, this material is piezoelectric, meaning that an applied stress (friction on the shoulders and back) generates an electrical charge. This charge creates electrical energy that can be transferred or stored to power GPS devices, L.E.D. headlamps, a cell phone, or an iPod Nano while on the trail.
You could store the energy all day and use it to power headlamps at night, or walk for 30 minutes and have enough energy to make a 2 minute cellphone call or consult your GPS for location and directions. All without the need to carry along heavy batteries in your pack. The energy generated in this manner is totally weightless, yet available for use as needed.
While other attempts have been made to capture or harvest physical energy or natural ambient energy and convert it to electrical power, there have been issues with ease of usability, as mentioned in the abstract accompanying the white paper produced by the engineers:
"Recent developments in the field have led to the design of a number of mechanisms that can be used to generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc. Many of these energy sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could disrupt the user's gait or endurance are avoided. These issues have arisen from previous attempts to integrate power harvesting mechanisms into a shoe such that the energy released during a heal (sic) strike could be harvested. This study develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack. The goal of this system is to make the energy harvesting device transparent to the wearer such that his or her endurance and dexterity is not compromised."
For hikers, backpackers and campers, this is a development to keep an eye on in the future.
