Ultralow-power Standoff Acoustic Leak Detection

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Views: 124
Electronics

The AquaPing is an ultra-low power smart sensor that provides stand-off acoustic water leak detection, even for leaks behind walls. No contact with plumbing is needed. All signal processing and analysis occurs on the device, so no audio is streamed to the cloud and eavesdropping is impossible.

When pressurized water escapes from a seam, crack, or loose fitting on plumbing, broadband high frequency acoustics are emitted. These signals can travel 30 ft or more in free-space and be detected by a remote sensor. This suggests a stand-off method for water leak detection that is substantially different compared to conventional contact moisture sensors and various types of smart flow meters installed on or inside of plumbing lines.

Acoustic leak detection combines the principles of glass breakage and smoke detectors. Glass breakage occurs on a timescale of a few seconds or less, requiring continuous data acquisition at rates approaching 1 kHz or more. Almost all plumbing leaks are persistent, which allows for sub-Hz sampling rates and exceptional battery life.

Glass breakage has the advantage of being generally louder than the ambient environment so that detector sensitivity is not an issue. Small water leaks, especially when separated from the sensor by acoustic barriers such as walls, are likely to be at or below the environmental background. Much higher sensitivity and noise mitigation are essential. This is addressed by mechanical, electronic, and digital filtering along with judicious use of statistical analysis.

The sensor is designed to be deployed as a remote, wireless network node. There are many dozens of wireless protocols, however, so it was decided to make the AquaPing agnostic to the host hardware and thus have the widest possible use cases. It will communicate with any controller using the popular I2C serial interface on a standard 3.3 V DC power bus.

The device is adept at identifying the onset of very small leaks via acoustic sensing and could be useful in situations where installing existing products may not be easy or convenient. An automated, inexpensive, battery-powered, smart acoustic detector can complement and augment the capabilities of a building monitoring system. Anticipated use cases are in smart homes and buildings, security systems, irrigation, dental and medical offices, critical plumbing installations, insurance loss mitigation, and water conservation. Although development has targeted water leaks, there can be other applications involving pressurized gases such as air, refrigerants, or steam.

The design is completely open-source. Schematics, firmware, and thorough documentation are all freely available on Github. Performance claims have been independently verified by UL in Chicago. Market validation was determined in a successful crowd funding campaign in 2022. Limited funds were raised on the Crowd Supply website, which allowed for a low-volume production run. Fully functioning circuit boards are available for purchase at Mouser and Digi-Key.

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  • ABOUT THE ENTRANT

  • Name:
    Michael Hasselbeck
  • Type of entry:
    individual
  • Patent status:
    none