ABLIC’s "Battery-less Water Leak Sensor" Verification Results on an Actual Bridge – Presented at the JSCE Conference

Seven Months of Monitoring Under Weather Conditions Including the Rainy Season, Typhoons, and Freezing Temperatures, Contribute to Verifying Sensor Effectiveness

ABLIC Inc. (President: Seiji Tanaka, Head Office: Minato-ku, Tokyo; hereinafter "ABLIC"), a company of the MinebeaMitsumi Group, together with West Nippon Expressway Engineering Chugoku Company Limited (hereinafter "NEXCO Engineering Chugoku") and BBM Corporation (hereinafter "BBM"), conducted a verification experiment for water leakage countermeasures and a simplified monitoring system on an actual bridge. In this experiment, a water-stopping method using BBM's self-amalgamating silicone tape (hereinafter "Simplified Water-stopping Method") was combined with a "Water Leakage Monitoring System" utilizing ABLIC’s "Battery-less Water Leak Sensor" equipped with "CLEAN-Boost_®" energy harvesting technology, and its effectiveness was verified. As a result, in addition to maintaining the water-stopping performance through the Simplified Water-stopping Method, verification results were obtained indicating that the system utilizing the "Battery-less Water Leak Sensor" is "effective for the early detection of water leaks from drainage pipes." Including these achievements, an academic paper was presented at the FY2026 Japan Society of Civil Engineers (JSCE) Annual Meeting on September 3^rd.

Background of Experiment and Social Issues
Social infrastructure in Japan, including road bridges, is aging rapidly, making it a critical national priority to improve the efficiency of maintenance and inspection and reduce the labor they require. Among these, the interior of "PC box girder bridges" (Prestressed Concrete box girder bridges) is a confined space that is dark and narrow, making inspection work difficult. If water leaks from drainage pipe joints passing through this interior, it risks causing severe damage, such as concrete spalling and corrosion of internal reinforcing steel. Because temporary repairs using conventional waterproof tape frequently suffered from re-deterioration, there was an urgent need to identify leaks early before they progressed to major damage requiring significant cost and time to repair. Furthermore, inside bridge structures where no power supply is available, installing wired or battery-powered sensors and performing battery replacement work pose a significant burden. As a result, there was a strong need for a monitoring method that is easy to install, low-cost, and capable of remote early detection without power supply concerns.

Role and Results of the "Battery-less Water Leak Sensor" in the Verification Experiment
To address these on-site challenges, a verification experiment was launched by three companies: NEXCO Engineering Chugoku, BBM (responsible for the "Simplified Water-stopping Method" using silicone tape), and ABLIC (providing the "Battery-less Water Leak Sensor" that self-generates electricity upon contact with water). The experiment targeted repaired sections on an actual bridge that had been in service for approximately 38 years, conducting verification testing over a period of about seven months from May 2025 to January 2026, ultimately confirming that practical and realistic operation is achievable.

ABLIC's Sensor Implementation Expertise That Led the Verification Experiment to Success
While the "Battery-less Water Leak Sensor" unit itself requires no power supply or batteries, securing power for the receiver that receives signals posed the biggest obstacle for field installation. Therefore, to overcome operational challenges—namely, (1) ensuring the system is easy and low cost to install, and provides stable remote detection without power supply concerns, and (2) enabling status tracking once or twice a day alongside long-term maintenance-free operation—ABLIC applied energy-saving technologies cultivated through water leak sensor installations in commercial buildings and factories. We adopted and tested an "intermittent drive method" that activates the receiver only at specified times and intervals. After evaluating multiple operation patterns taking into account the characteristics of the "Battery-less Water Leak Sensor," we demonstrated that activating the receiver for "5 minutes, twice a day" fully satisfies field needs while keeping power consumption to an absolute minimum. Furthermore, stable communication quality was maintained even inside box girders with harsh radio wave environments, yielding data indicating that "continuous operation for approximately three years is possible" using only a general-purpose battery. Moving forward, we aim to expand the scope of application by deploying the system onmultiple bridges and conducting long-term performance evaluations.

Overview of Presentation at JSCE Conference

• Paper Presented at the "JSCE Annual Meeting"
  Through approximately seven months of monitoring encompassing various seasonal and weather conditions — such as the rainy 　　season, typhoons, and freezing temperatures — it was verified that the system maintained its water-stopping performance and 　　achieved remote early detection on an actual bridge using the 'Battery-less Water Leak Sensor.
  Based on these achievements, a joint paper was presented by NEXCO Engineering Chugoku, BBM, and ABLIC at the FY2026　　Japan Society of Civil Engineers (JSCE) Annual Meeting.

• Conference Name:
  FY2026 JSCE Annual Meeting
  (https://pub.confit.atlas.jp/ja/event/jsce2026/session/Q6cxO3ic)　*only Japanese is available

• Presentation Title:
  Water Leakage Countermeasures for Drainage Pipe Joints Inside Box Girders and Field Verification of a Simplified Monitoring System

• Presenters (in order of paper listing):
  West Nippon Expressway Engineering Chugoku Company Limited
  ABLIC Inc.
  BBM Corporation

Future Outlook
ABLIC aims to extend the continuous operation period verified in this experiment from three years to five years—matching standard periodic inspection intervals—while continuing verification in various environments. Moving forward, ABLIC will broadly expand the deployment of this solution across road infrastructure, as well as various building and facility maintenance sectors including commercial buildings, factories, and industrial plants. Furthermore, in addition to Bluetooth, ABLIC will continue developing and integrating next-generation communication technologies that cover broader areas, aiming to evolve the system to accommodate diverse on-site requirements.

About the "Battery-less Water Leak Sensor"
https://www.ablic.com/en/semicon/products/cb/wls/