As our need for electronic gadgets and sensors grows, researchers are finding new ways to keep devices powered for longer on less energy.
The latest sensor invented in the laboratory can run for an entire year with a single energy saving aided by a physics phenomenon known as the quantum tunnel.
The tunnel aspect means that this simple and inexpensive device (consisting of only four capacitors and two transistors) using a 50 million electron start can continue for a longer period of time.
The rules of quantum physics, which apply at the smallest atomic scales, mean that electrons can behave both as particles and as waves, and scientists were able to utilize that behavior to accurately control electron current from one side of an orbit to it. other.
“If you want to get to the other side, you have to physically climb the hill,” says electrical engineer Shantanu Chakrabartty of Washington University in St. Louis. Louis.
“Quantum tunnel is more like walking through the hill.”
To generate power, devices must be able to give electrons a hard enough push – something known as threshold energy, because that push must be above a certain threshold. When trying to make devices that run on as little power as possible, it can be difficult to hit this threshold.
This is where the quantum mechanics part comes in: by taking certain approaches to shape the ‘tray’ or barrier to be overcome, it is possible to control the flow of electrons in a number of different ways.
In this case, the ‘hill’ is what is called a Fowler-Nordheim tunnel barrier, less than 100 atoms thick. By building the barrier in this way, the scientists were able to slow down the flow of electrons straight down, while keeping the system (and the device) stable and on.
“Imagine an apple hanging from a tree,” says Chakrabartty. “You can shake the tree a little, but the apple does not fall. You have to give it enough of a tug to shake the apple loose.”
“It’s the minimum amount of energy needed to move an electron across a barrier.”
Within the unit there are two dynamic systems, one with a transducer (energy converter). The team had to work backwards to shape their hill or barrier, first measuring electron motion and then refining the Fowler-Nordheim setup accordingly.
What the researchers ended up with was a device that uses the interplay between the two internal systems to record and log data without additional power. Something like this could e.g. Used to monitor blood glucose or to measure temperature for vaccine transport – batteries are not required.
In this case, the transducer used was a piezoelectric accelerometer, who sensed and were driven by ambient movement, but the basic principles of the long-lasting, high-efficiency system can also be applied to other types of energy harvesting.
“Right now, the platform is generic,” says Chakrabartty. “It just depends on what you pair to the device. As long as you have a transducer that can generate an electrical signal, it can self-drive our sensor data logger.”
The research is published in Nature communication.