Bubble wrap bursting allows acoustic testing without power supply

Nondestructive testing allows engineers to assess the integrity of structures such as pipelines, tanks, bridges, and machinery without dismantling them. Traditional approaches rely on speakers, lasers, or electrical sparks. Although effective, these systems can be difficult or dangerous to use in flammable or confined areas and require significant power to function effectively.

Now, new research from Japan, available online in the journal Measurement, shows how common packaging materials can replace power-hungry devices in non-destructive testing. A team led by Professor Naoki Hosoya, along with Shuichi Yahagi of Tokyo City University, Toshiki Shimizu and Seiya Inadera of Shibaura Institute of Technology, and Ituro Kajiwara of Hokkaido University, have discovered a simple method to use bubble wrap to inspect pipes for hidden defects.

Researchers have discovered that the sharp cracks caused by bubble bursts could be a promising alternative to the expensive, energy-dependent tools typically used in non-destructive testing. The researchers claim their method can detect objects inside pipes with an accuracy of less than 2%, without the need for electricity or heavy equipment.

“My team and I sought a simpler solution: a sound source that is small, cheap, and works safely in almost any environment,” Professor Hosoya said. “Bubble wrap is small, inexpensive, can be mass-produced, and does not require a power source, so it is useful at construction sites.”

The researchers tested several types of bubble wrap and measured their acoustic properties, including peak sound pressure, pulse width, and frequency range. Surprisingly, the burst produced frequencies of up to 40 kilohertz. This is sufficient for accurate acoustic testing. The team then built a system that used bubble wrap as the sound source, a microphone to collect the signal, and a computer to perform wavelet-based acoustic analysis to track how the sound waves reflected within the pipe.

Compared to traditional impulse sources such as speakers, firecrackers, and laser-induced plasma, bubble wrap systems eliminate complex wiring and potential hazards. Safe for use in flammable environments where electrical equipment poses a hazard. By analyzing how the echo changes when a foreign object is present, we were able to pinpoint the location of the foreign object with high accuracy.

Bubble wrap, long considered a disposable packaging material, has acquired a new scientific role in this study. By adjusting the size of the bubbles and the thickness of the membrane, the team was able to change the intensity and direction of the sound produced, turning a common material into a controllable tool for acoustic testing. The system was proven to be accurate and portable.

Using only a sheet of bubble wrap and a microphone, the team was able to identify small changes in reflected sound that revealed the location of internal obstacles. The accuracy of these measurements was comparable to results obtained using much more complex devices.

The flexibility of this technology also allows it to be adapted to different situations. Changing the bubble size and internal pressure changes the sound frequency, so it can be applied to various pipe diameters and materials. Easy setup allows a single operator to perform the inspection with minimal training.

“Compared to traditional acoustic excitation devices, this system has sufficient acoustic performance, including a near-impact, non-directional radiation pattern, repeatability, cost-effectiveness, portability, and no need for a power source for practical application, so it has the potential to be used in NDT to detect foreign objects in pipes in construction sites, such as building construction,” Professor Hosoya explained.

What started as a fleeting curiosity, a casual observation while popping bubble wrap, has turned into a practical acoustic measurement tool. This work demonstrates how familiar materials can yield precise scientific applications when examined systematically.

Rather than relying on bulky or specialized equipment, the researchers used a jet of compressed air from the plastic to perform the same function. The group plans to further test the system under various temperature and pressure conditions and explore ways to develop a compact handheld version suitable for field testing. Continued improvements may increase sensitivity and allow detection of deeper and more complex structures.

This research shows that meaningful innovation doesn’t necessarily rely on complex materials or big budgets. Sometimes it emerges from everyday experiences. In this case, simple, inexpensive and widely available sheets of bubble wrap have become a new tool for inspecting structures without causing damage.