New NOx Sensor Wins the 72nd Okouchi Memorial Prize for Production

NGK INSULATORS, LTD. (hereinafter, “NGK”) announced that the development and early mass production of a porous protective layer for its thick-film laminated zirconia NOx sensor, developed and commercialized by NGK, has won the 72nd Okouchi Memorial Prize for Production (FY2025), presented by the Okouchi Memorial Foundation.

The Okouchi Prize was established in honor of Dr. Masatoshi Okouchi, the third Director of RIKEN, and is awarded by the Okouchi Memorial Foundation in recognition of outstanding achievements in research and development of production engineering, production technologies, and the implementation of advanced production methods in Japan. It is regarded as one of the most prestigious awards in Japan’s industrial sector.

NGK’s thick-film laminated zirconia NOx sensor is the world’s first high-precision automotive NOx sensor that NGK developed and successfully commercialized. This award recognizes NGK’s development of the porous protective layer*¹ for the NOx sensor and the establishment of its mass production technology.

NGK’s NOx sensors are installed directly in automotive exhaust systems and are capable of measuring NOx (nitrogen oxides) concentration in exhaust gas with high precision at the parts-per-million (ppm) level in real time. The sensors detect NOx concentrations in exhaust gas and are used for controlling exhaust gas purification systems and for onboard diagnostics.

In recent years, automotive exhaust emission regulations have been strengthened worldwide, and Real Driving Emissions (RDE) regulations—particularly in Europe—have been introduced to evaluate emissions under actual driving conditions. As a result, NOx sensors are required to maintain stable measurement performance even under conditions such as immediately after engine start, when moisture levels in the exhaust system are high and rapid temperature changes occur. However, because NOx sensors are mounted directly in exhaust pipes, these conditions place significant thermal shock stress on ceramic sensor elements.

To address this challenge, NGK has steadily advanced its technology development in line with increasingly stringent emission regulations. In 2017, NGK established a forming technology for a porous protective layer using a plasma spray method. Furthermore, in 2022, NGK enhanced water resistance*² by adopting a dual-layer protective structure, thereby mitigating thermal shock to the sensor under actual operating conditions. By timely introducing these technologies to the market in line with regulatory trends, NGK has successfully achieved early mass production of its NOx sensors.

Under its medium- to long-term vision, “NGK Group Vision: Road to 2050,” the NGK Group is aiming to transform its business portfolio toward the Carbon Neutral (CN) and Digital Society (DS) fields. By continuing to address social challenges through automotive exhaust gas purification technologies, NGK will contribute to realizing a carbon-neutral society in the mobility domain.

• *1A protective structure in which a layer containing numerous fine pores is applied to the outer surface of the sensor element to mitigate the effects of rapid temperature changes and moisture.
• *2Water resistance: The ability to withstand exposure to water without damage while operating at high temperatures.

Award Overview

Award	The 72nd Okouchi Memorial Prize for Production
Organizer	Okouchi Memorial Foundation
Awarded Achievement	Development and Early Mass Production of a Porous Protective Layer for a Thick-Film Laminated Zirconia NOx Sensor
Awarded Company	NGK INSULATORS, LTD.
Award Ceremony	March 24, 2026, Japan Industrial Club Hall (Chiyoda-ku, Tokyo)

Related information
NOx Sensors for Engine Exhaust Gas

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