Will your shirt charge your phone?
The world of energy harvesting is a strange one, with researchers trying to find ways to use movement, temperature changes, biochemical reactions, wheel motion, and a myriad of other everyday functions to generate small amounts of electricity that can be stored and used to power devices. Of course the amounts of energy generated from regular motion are minute, so the repetitive nature of the collection mode must be high as does the efficiency of the energy harvesting device. That said, one of the biggest problems with such concepts is that every day human motion does not fit that model, with general repetition rates far too slow to be useful. The example often given is Usain Bolt, the fastest man on earth, is considered by scientists as a machine working at 5Hz, while most of the materials that can convert motion to energy need 100Hz to become effective.
But researchers at Vanderbilt University have developed a material that can harvest energy even at our sloth like human levels, giving rise to the hope that by just moving around, you could be generating power to charge a device. The device, which was developed as an outgrowth of research on the response of battery materials to bending and stretching, is essentially a battery with the same material for the anode and the cathode, which means it cannot store energy as a normal battery would. However, the voltage changes that occur in the device when it is bent or twisted can translate human motion into electrical current. The material itself is only a few atoms thick and is made of black phosphorous, a room-temperature stable form of highly volatile white phosphorous, which acts like graphite and can be easily manipulated. This gives it a significant advantage over the typical piezoelectric materials that are common in energy harvesting, but need much more motion to generate power, and generate at 5% to 10% efficiency, even at those higher motion levels. The Vanderbilt material can generate 25% efficiency when the user is just sitting or standing, giving rise to the hope that one day Mom and Dad can lower their electricity bill if they attach Jr. and his basement buddies to their energy harvesting grid.
This is research, and while the material is thin enough to be impregnated into fabrics without changing their texture or look, lots of work still needs to be done to bring the concept to commercialization levels, but wouldn’t it be wonderful to be able to charge your smartwatch while playing tennis, or charge your Bluetooth headset just by walking down the street? Of course, we see those who are at 5% charge on their smartphones wildly waving their arms around while walking down the street, but what about building it into shoes or flags that wave in the breeze or even those weird giant tube people that car dealerships use? The applications are enormous, with the ultimate look being the attachment of such material to the lips to generate oodles of energy from the never-ending chattering of high school girls on the subway…
But researchers at Vanderbilt University have developed a material that can harvest energy even at our sloth like human levels, giving rise to the hope that by just moving around, you could be generating power to charge a device. The device, which was developed as an outgrowth of research on the response of battery materials to bending and stretching, is essentially a battery with the same material for the anode and the cathode, which means it cannot store energy as a normal battery would. However, the voltage changes that occur in the device when it is bent or twisted can translate human motion into electrical current. The material itself is only a few atoms thick and is made of black phosphorous, a room-temperature stable form of highly volatile white phosphorous, which acts like graphite and can be easily manipulated. This gives it a significant advantage over the typical piezoelectric materials that are common in energy harvesting, but need much more motion to generate power, and generate at 5% to 10% efficiency, even at those higher motion levels. The Vanderbilt material can generate 25% efficiency when the user is just sitting or standing, giving rise to the hope that one day Mom and Dad can lower their electricity bill if they attach Jr. and his basement buddies to their energy harvesting grid.
This is research, and while the material is thin enough to be impregnated into fabrics without changing their texture or look, lots of work still needs to be done to bring the concept to commercialization levels, but wouldn’t it be wonderful to be able to charge your smartwatch while playing tennis, or charge your Bluetooth headset just by walking down the street? Of course, we see those who are at 5% charge on their smartphones wildly waving their arms around while walking down the street, but what about building it into shoes or flags that wave in the breeze or even those weird giant tube people that car dealerships use? The applications are enormous, with the ultimate look being the attachment of such material to the lips to generate oodles of energy from the never-ending chattering of high school girls on the subway…
Figure 4 - Black Phosphorous Nanosheet Energy Harvester - Source: ACS.org
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