Scientists in Finland have made a breakthrough in wireless electricity by successfully transmitting power through open air using ultrasonic sound waves and laser-based systems. The research is being led by teams from the University of Helsinki and the University of Oulu, working alongside scientists from Spain and Canada.
Together, they have demonstrated for the first time that electric sparks can be guided safely and precisely through air using ultrasonic fields. Electric sparks are already widely used in daily life. They are essential for welding, powering certain electronic systems, killing germs, and igniting fuel in some car engines.
However, controlling sparks in open air has always been a serious challenge. Sparks tend to split into chaotic branches and naturally move toward nearby metal objects, making them unpredictable and difficult to manage.
In the new study, researchers found a way to control this behavior. By using high-intensity ultrasonic sound waves, they were able to create invisible paths in the air that guide electrical sparks along a chosen route. This method allows electricity to bend around obstacles and hit specific targets, even when those targets are not made of conductive material.
“We observed this phenomenon more than one year ago, then it took us months to control it, and even longer to find an explanation,” said Dr. Asier Marzo from the Public University of Navarre, who led the research work.
Scientists explained that the process works because electric sparks heat the air as they travel. When air heats up, it expands and becomes less dense. Ultrasonic waves then shape this hot, lighter air into regions where sound intensity is strongest. Because electricity prefers paths with lower resistance, the next sparks follow these lighter air channels. This creates a stable and repeatable pathway for electricity to move through open space.
In one experiment, researchers successfully guided an electric spark measuring four centimeters around an obstacle using ultrasonic fields. This level of precision had never been achieved before without using powerful lasers.
“Precise control of sparks allows their utilization in a wide variety of applications, such as atmospheric sciences, biological procedures, and selective powering of circuits,” said Professor Ari Salmi from the University of Helsinki.
Before this discovery, sparks could only be guided using laser-induced discharges, often referred to as electrolasers. These systems require dangerous, high-powered lasers and very precise timing between the laser pulse and the electric discharge. They are complex, expensive, and can pose risks to human eyes and skin.
The new ultrasonic method removes many of these risks. Researchers confirmed that ultrasound-based control is safe for the eyes and skin, does not require extreme laser power, and can operate continuously. The equipment is also compact and affordable, making it more practical for real-world applications.
Published in the Science Advances journal, the study shows how ultrasonic fields can guide plasma sparks dynamically within milliseconds. Researchers noted that this enables fast, accurate, and non-dangerous control of high-voltage electricity.
“Here, we show that ultrasonic fields can guide plasma sparks, even around obstacles,” the researchers stated in the study. “The ultrasonic beams can be directed dynamically and within milliseconds, enabling precise, nondangerous, and fast control of high-voltage sparks.”
Alongside ultrasonic spark control, Finnish researchers are also advancing other forms of wireless power transmission. The major area is power-by-light, where high-powered lasers transmit electricity to distant receivers. This approach could be especially useful in hazardous locations such as nuclear plants, chemical factories, and disaster zones where physical cables are unsafe.
Researchers are also developing radio-frequency energy harvesting systems that convert ambient signals into usable electricity. These systems could power low-energy Internet of Things devices and may eventually replace millions of small batteries used worldwide.
“I am excited about the possibility of using very faint sparks for creating controlled tactile stimuli in the hand, perhaps creating the first contactless Braille system,” said Josu Irisarri, the first author of the publication.
- by fatima khan
