Mark Megahan
Researchers at the University of Alabama were amazed to discover what can happen with a simple piece of scotch tape. Specifically, the two sided kind. It dramatically increased the power output of a funky sort of mini-generator they’re working on. The best part of their discovery is that this is definitely one you CAN try at home. It may not be the off-grid power source you’ve been searching for but you can whip up a snazzy pair of LED loafers.
The miracle of scotch tape
A group of forward thinking researchers at the Huntsville campus of the University of Alabama “have determined that double-sided Scotch tape can improve triboelectric power generators.” You probably never heard of them but they’ve been around for ages.
The basic principle is to take mechanical and thermal energy and harvest tiny amounts at a time. Thanks to their breakthrough, anyone can make “an inexpensive generator that works well.”
Another key to the practical use of these gizmos is the fact that standard principles of electricity prove that current sources can be combined to produce more current and higher voltages. In this case, you harvest milliwatts at a time.
The main parts you need are some common PET plastic, aluminum, and double-sided tape. On a good day, you can expect to generate 21.2 mW with “the device stimulated at 20 Hz.” Before the discovery, the best they could hope for was “7.6 mW in the same configuration.”
Aluminized PET film is easy to come by in large rolls for under $11 making this an ideal hobby project for the experimental minded. Scotch tape is everywhere but you need the two sided kind with glue on both faces.
There are all sorts of project kits which can be adapted with some creativity because “it is something of a standard test to show how many LEDs you can power with devices like this.” They whipped up power sources for “a flashlight, 476 LEDs, and a laser diode using the new generators.”
An array of applications
In their paper, they note how “a small-scale energy harvesting device is needed to power low-power profile electronic systems in many different applications.” Things like “structural health monitoring, wearable sensors, and environmental monitoring systems.”
Ideally, they should “be built as stand-alone systems with the capability of harvesting ambient mechanical energy and converting it into electrical power.” Like a pair of shoes that powers your cell phone. That’s in the future but you can have lights on your shoes powered by your shoes. Thanks to scotch tape.
The process works through “a friction of two surfaces with different materials.” Most of the ones tried so far use expensive ones that are hard to work with.
“In this paper, a novel triboelectric generator concept is proposed, in which a simple design was adopted by using a conventional double-sided tape (with acrylic adhesive layer) and a metalized polyester film (i.e., an aluminum layer coating on one side) (PET/Al) to serve as triboelectric layers. It is worth noting that no special fabrication scheme is required in the current design.” In other words, go ahead and try this at home!
“Power generation is achieved via a contact–separation motion.” Charges “are developed on the interface between a double-sided tape and a PET/Al layer. However, the strong bonding nature of acrylic adhesive on the tape induces a significant charge compared to that of a non-tacky triboelectric layer.”
“During the separation phase, the air breakdown via an electric spark occurs at the interface. Such rapid charge removal in triboelectric layers allows existing electrons from the ground flow back to the aluminum layer to realize a different mechanism compared to the capacitance behavior, as observed in a typical TENG device.” In English, the stickiness of the tape layers grabbing each other and letting go does the trick as an amplifier.
