Scientists in Finland have successfully guided electric sparks through open air using ultrasonic sound waves, marking the first time this has been done without the use of dangerous high-powered lasers. The research, published in the Science Advances journal, was led by teams from the University of Helsinki and the University of Oulu, in collaboration with scientists from Spain and Canada.
- What the Experiment Actually Proved
- Why This Beats the Old Method
- 5 Real Applications This Technology Could Enable
- Finland’s Broader Push on Wireless Power
- What Competitors Got Wrong
- The Science Behind Acoustic Plasma Channels
- Safety Profile Compared to Electrolasers
- What Comes Next
- Frequently Asked Questions
- Has Finland successfully transmitted wireless electricity to homes?
- How do ultrasonic waves guide electric sparks?
- Is this the same technology as wireless charging for phones?
- What is an electrolaser and how does this discovery improve on it?
- Could acoustic spark control power IoT devices?
- What journal published this research?
- Who led this research?
- What is the maximum distance the spark was guided?
This is not a wireless power grid for homes. What researchers achieved is precise, safe control of high-voltage electrical sparks through air, something that has never been possible with compact, affordable equipment before. That distinction matters, and most competitor coverage misses it.
What the Experiment Actually Proved
The core finding is specific: high-intensity ultrasonic (US) sound waves create invisible low-density channels in air that guide electrical plasma sparks along a chosen path. In one experiment, researchers steered a 4-centimeter spark around a physical obstacle with millisecond-level precision. No prior technique achieved this without bulky, eye-hazardous laser systems.
“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.
The physics behind it are direct. An electric spark heats the air it travels through. Hot air expands and becomes less dense. Ultrasonic waves then organize this lighter, heated air into regions of maximum sound intensity. Electricity naturally follows the path of least resistance, so subsequent sparks lock onto these low-density acoustic channels. The result is a stable, repeatable, steerable pathway for high-voltage electricity through open space.
Why This Beats the Old Method
Before this discovery, the only way to steer sparks through air was with laser-induced discharges, known as electrolasers. Electrolasers have 3 serious disadvantages: they require extremely high laser power, precise microsecond-level timing between the laser pulse and the electrical discharge, and direct risks to human eyes and skin.
The ultrasonic approach removes all 3 problems at once. The equipment is compact, the system operates continuously rather than in pulses, and it poses no known hazard to eyes or skin. Cost drops significantly too, making deployment practical outside of specialized laboratories.
“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.
5 Real Applications This Technology Could Enable
Researchers identified specific use cases where acoustic spark control delivers clear advantages over existing methods:
Atmospheric science. Guided sparks allow researchers to trigger and study electrical discharge phenomena in controlled conditions, including simulated lightning behaviour in lab environments.
Biological and medical procedures. Low-intensity sparks, precisely guided to skin or tissue surfaces, have potential for targeted sterilisation, wound treatment, and non-contact surgical tools. First author Josu Irisarri pointed to one particularly striking possibility: “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.”
Selective circuit powering. Sparks guided to specific non-conductive targets could activate circuits without physical contact, enabling new interface designs for electronics and robotics.
Plasma generation in hazardous environments. In settings where direct contact is impossible or dangerous, acoustic spark steering could replace cable-dependent systems.
Germicidal applications. Electric sparks already kill microorganisms in industrial sterilisation. Acoustic control makes targeted, localised disinfection feasible without contact.
Finland’s Broader Push on Wireless Power
The ultrasonic spark work is one part of a larger research push in Finland toward wireless electricity transmission. Finnish researchers are advancing 3 parallel tracks.
The first is power-by-light, where high-powered lasers carry electricity to distant receivers converted through photovoltaic cells. This approach is particularly relevant for hazardous environments such as nuclear plants, chemical factories, and disaster zones, where running physical cables creates unacceptable safety risks.
The second track is radio-frequency (RF) energy harvesting, where ambient electromagnetic signals from Wi-Fi, cellular networks, and broadcast frequencies are captured and converted into usable electricity. This technology targets the low-power Internet of Things (IoT) device market, where billions of small sensors currently rely on disposable batteries. RF harvesting systems could eliminate the need for battery replacement across massive sensor networks, dramatically cutting maintenance costs and electronic waste.
The third track, and the subject of the Science Advances paper, is acoustic plasma guidance, which is now proven effective under laboratory conditions.
None of these 3 systems is ready to replace conventional wired power grids. That fact is an important context that viral coverage frequently omits. Transmission efficiency, safety at scale, and regulatory approval all remain active challenges. The genuine significance of this research lies in the precision, safety, and affordability it introduces for specialised, non-grid applications.
What Competitors Got Wrong
Multiple articles covering this story either overstated the breakthrough, claiming Finland had achieved “cable-free city-scale electricity transmission,” or undersold it by focusing only on limitations. Neither framing is accurate.
The 4-centimetre guided spark is genuinely unprecedented without laser equipment. The acoustic control method is the first of its kind to be reproducible, safe, affordable, and continuously operable. Its value is not in replacing the power grid. Its value lies in enabling precise electrical control in medical devices, scientific instruments, robotics, and hazardous industrial environments, where current techniques are either too dangerous or too expensive.
Related research on wireless energy delivery: Japan’s Shimizu Corporation proposed the ‘Luna Ring’ to transmit solar power from the Moon to Earth, and Kawasaki has launched the world’s first commercial gas engine for a 30% hydrogen blend, both representing the same energy innovation trend this research belongs to.
The Science Behind Acoustic Plasma Channels
To understand why this works, consider what happens to air when a spark travels through it. A spark is a rapid electrical discharge, a plasma event that superheats the air along its path to temperatures of several thousand degrees Celsius (roughly 5,400 to 9,000 degrees Fahrenheit). This extreme local heating causes the air to expand instantly, dropping its density along the discharge path.
Ultrasonic waves operating at frequencies above 20 kHz interact with this density gradient. The waves trap and shape the low-density hot air into specific spatial configurations based on the acoustic field pattern. Because electrical resistance in air drops with decreasing density. The next spark discharge preferentially follows the acoustic channel rather than branching randomly.
This is the mechanism researchers from the University of Helsinki and the University of Oulu have studied. This is working with Dr Marzo’s team at the Public University of Navarre, spent over a year identifying and controlling. The study was further supported by collaborators from Canada. Those whose contributions to the experimental design helped validate results across independent laboratory settings.
Safety Profile Compared to Electrolasers
The comparison to electrolasers deserves specific data. Electrolaser systems typically operate with pulsed ultraviolet lasers delivering energies of 1 millijoule (mJ) to 100 mJ per pulse, at repetition rates of 10 Hz to 100 Hz. The peak intensities involved (often exceeding 10^10 watts per square meter, or W/m²) are well above the threshold for immediate retinal damage, classified as Class 4 laser hazards under IEC 60825-1 standards.
Ultrasonic transducers used in acoustic spark guidance operate at sound pressure levels typically between 150 dB and 170 dB (referenced to 20 micropascals, or µPa). It is well within the ranges already used in medical ultrasound equipment and industrial cleaning systems. No ionizing radiation, no thermal optical hazard, no coherent beam risk. The system can run continuously at these levels without special protective enclosures required around operators.
This safety difference is not minor. It is the primary practical reason why the acoustic method could reach clinical, consumer, and field deployment environments that electrolasers never could.
What Comes Next
The paper in Science Advances establishes acoustic plasma guidance as a scientifically validated phenomenon. The next phase of research will focus on scaling the guidance range beyond 4 centimeters (1.6 inches), increasing spark energy while maintaining directional control, and integrating acoustic guidance with the power-by-light and RF harvesting systems already in development at Finnish universities.
Commercialization timelines remain speculative. University of Helsinki researchers indicated that atmospheric science and biological procedure applications are the near-term targets, as both fields already work with controlled spark and plasma systems and have existing regulatory frameworks to build on.
For the IoT and sensor-powering application, the RF harvesting track remains the more mature pathway. Acoustic spark guidance will likely reach niche precision applications, such as the contactless Braille system Irisarri described, before broader adoption.
The energy technology space is moving fast. For more coverage of breakthroughs in wireless and next-generation power systems, see Nobel Laureate Develops Machine That Harvests 1,000 Liters of Water from Thin Air Daily and China’s compact microwave weapon capable of disabling satellites, both of which reflect the same convergence of physics and engineering redefining what energy can do.
Frequently Asked Questions
Has Finland successfully transmitted wireless electricity to homes?
No. Finland has demonstrated controlled guidance of electric sparks through air in laboratory conditions. No system currently transmits electricity wirelessly to homes or replaces conventional wired grids at any scale.
How do ultrasonic waves guide electric sparks?
Sparks heat the air they travel through, reducing its density. Ultrasonic waves then organize this low-density air into shaped channels based on acoustic field intensity. Electricity follows the path of least resistance, so subsequent sparks reliably track these acoustic channels.
Is this the same technology as wireless charging for phones?
No. Phone wireless charging uses near-field electromagnetic induction, which works over distances of a few millimeters to centimeters. Acoustic plasma guidance steers high-voltage spark discharges through open air, targeting different applications entirely.
What is an electrolaser and how does this discovery improve on it?
An electrolaser uses a high-powered laser pulse to ionise an air channel, which is then followed by a high-voltage discharge. Electrolasers require precise microsecond-level timing, hazardous Class 4 laser power, and expensive equipment. The ultrasonic method requires none of these, operates continuously, and poses no optical hazard.
Could acoustic spark control power IoT devices?
Not directly. The acoustic spark guidance technique is used in applications requiring precise spark placement, such as medical procedures and selective circuit activation. IoT battery replacement is being addressed separately through radio-frequency energy harvesting research at Finnish universities.
What journal published this research?
The study was published in Science Advances, an open-access journal from the American Association for the Advancement of Science (AAAS).
Who led this research?
Dr. Asier Marzo from the Public University of Navarre (Spain) led the experimental work, with Professor Ari Salmi from the University of Helsinki and teams from the University of Oulu and collaborating institutions in Canada contributing to the study.
What is the maximum distance the spark was guided?
Researchers guided a spark measuring 4 centimetres (approximately 1.6 inches) around a physical obstacle. This represents the first time this level of precision was achieved without powerful laser systems.
