Listening to the body’s quietest, yet most dynamic movements

Pohang University of Science & Technology (POSTECH)

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The sensor employs a piezoelectric material as the vibration diaphragm, enabling operation without an external power supply. The circular diaphragm is supported by four interlocking, star-shaped support layers that allow free airflow, facilitating hyperpacked sensor integration for accurate detection of even the faintest vibrations.

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Credit: POSTECH

The human body continuously generates a rich spectrum of vibrations—often without us ever noticing. Everyday unconscious activities such as breathing, speaking, and swallowing all produce subtle yet distinct mechanical signals. Although these faint vibrations carry valuable information about physiological state, they have long been difficult to capture accurately using conventional wearable devices.

 

Recently, a research team led by Professor Kilwon Cho of the Department of Chemical Engineering at Pohang University of Science and Technology (POSTECH), along with Ph.D. candidate Kang Hyuk Cho and postdoctoral researcher Dr. Jeng-Hun Lee, has developed a wearable vibration sensor capable of precisely detecting these subtle yet highly dynamic signals, without requiring any external power source. This breakthrough opens new possibilities for wearable medical and healthcare technologies and demonstrates strong potential as a core sensing platform for next-generation smart devices. The work was published in the inaugural issue of Nature Sensors, a newly launched Nature-family journal, in January 2026.

 

Sounds produced by the human body span a wide range of frequencies. Physiological signals such as breathing, swallowing, and speech typically occur at lower frequencies, while sounds such as coughing or groaning emerge at relatively higher frequencies. Accurately capturing these signals requires precise detection of the minute vibrations transmitted to the skin surface across a broad frequency spectrum. However, existing wearable vibration sensors often lack sufficiently high and uniform sensitivity across this range or depend on external power sources. Moreover, their performance frequently degrades when in contact with skin or sweat, limiting their practicality in real-world wearable applications.

 

To address these challenges, the researchers combined two fundamentally different sensing mechanisms. They integrated a piezoelectric material—which generates electrical charges when subjected to mechanical stress-with a capacitive sensor that detects signals through changes in the distance between electrodes. By using the electricity generated by the piezoelectric component to power the capacitive sensor, the team created a device that is both self-powered and capable of maintaining high, uniform sensitivity across a broad frequency range.

 

The team also introduced an elegant sensor architecture designed to improve air ventilation while maximizing sensor density. Beneath the vibration diaphragm, star-shaped micro-supports are arranged, with a circular diaphragm positioned at the center where the four supports interlock. This structure allows air to flow freely between the supports, preventing trapped air from interfering with the diaphragm’s movement. As a result, sensors can be packed at ultra-high densities without compromising performance.

 

The sensor demonstrated high sensitivity across frequencies ranging from 80 to 5,000 Hz and was able to detect vibrations as small as 0.01 g (gravitational acceleration). When attached to a person’s neck, it successfully captured minute vocal-cord vibrations, enabling accurate recognition of physiological signals such as speech, breathing, and coughing. When mounted on sound-emitting objects, the device precisely measured surface vibrations, functioning much like a high-fidelity contact microphone. These results show that the sensor can reliably detect even extremely faint vibrations that are often missed by conventional technologies.

 

“The vibration sensor we developed can sensitively detect extremely small vibrations across a broad frequency range,” said Professor Kilwon Cho, who led the study. “When attached to the skin, it can accurately capture subtle signals generated by the human body, making it highly promising for wearable healthcare applications. At the same time, by recording vibrations from sound-emitting objects, it can enable high-fidelity sound recording, suggesting strong potential as a thin, flexible, attachable contact microphone,” he added.

 

This research was supported by the Bridge Convergence Research and Development Program and the National Agenda Basic Research Program funded by the Ministry of Science and ICT of Korea.

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Article Title

Hyperpacked piezoelectric-powered capacitive sensor array for high-fidelity vibration detection