In a groundbreaking advance poised to transform environmental and industrial safety monitoring, researchers at the Korea Research Institute of Standards and Science (KRISS) have developed an innovative gas sensor technology that leverages low-cost, safe visible-light LED illumination to detect a spectrum of hazardous gases with remarkable precision. This next-generation sensor technology addresses longstanding limitations of traditional gas detection methods by significantly reducing power consumption and enhancing multi-gas selectivity, heralding a new era in compact, energy-efficient, and highly accurate gas sensing solutions.
Conventional industrial gas sensors typically rely on high-temperature operation, often heating sensor elements to temperatures between 200 and 400 degrees Celsius. This thermal activation enhances chemical reactivity with target gas molecules, thereby improving sensor response and sensitivity. However, maintaining such elevated temperatures necessitates continuous power input and integrated micro-heaters, which substantially increase the sensor’s energy footprint and operational costs. Furthermore, the thermal cycling accelerates the physical degradation of sensor materials, ultimately shortening device lifespan and reliability — major obstacles for long-term deployment, particularly in environments requiring continuous monitoring.
Meanwhile, emerging alternatives employing ultraviolet (UV) or visible-light LEDs to replace heater elements have attracted considerable attention. UV-based LED sensors offer enhanced photochemical reactivity but introduce significant safety concerns due to the harmful effects of UV radiation on human skin and eyes, thereby limiting their applicability in populated or sensitive settings. Conversely, visible-light LED sensors safely circumvent these risks but historically suffer from insufficient gas reactivity, restricting their ability to detect gases other than nitrogen dioxide, and curtailing their practical use for comprehensive multi-gas monitoring.
To overcome these challenges, the KRISS research team ingeniously engineered a nanoscale heterojunction structure combining indium sulfide (In₂S₃) with indium oxide (In₂O₃). This Type-I heterojunction configuration functions as an energy well that curtails the dispersal of photo-generated charge carriers, effectively accumulating them at the reactive sensor surface. By maximizing the utilization efficiency of the photon energy from blue visible LED illumination, this nanostructure enables robust interaction with diverse gas molecules at room temperature, without the need for any external heating, and circumvents the power-intensive operation regimes of traditional sensors.
Capitalizing on this advanced heterojunction foundation, the researchers further enhanced sensing specificity by functionalizing sensor elements with nanoparticles of platinum (Pt), palladium (Pd), and gold (Au). Each noble metal catalyst selectively interacts with particular hazardous gases, thereby enabling the sensor array to mimic a rudimentary electronic nose (E-nose). This bioinspired system exhibits high discriminatory power, reliably identifying gases such as hydrogen, ammonia, and ethanol even within complex, mixed-gas environments, paralleling the nuanced gas sensing capabilities of the human olfactory system.
Performance assessments spotlight the sensor’s extraordinary sensitivity, achieving a limit of detection (LOD) as low as 201.03 parts per trillion (ppt). This sensitivity represents an approximate 56-fold enhancement compared to existing LED-based gas sensors, fundamentally shifting the boundaries of visible-light photoreactive sensing. Moreover, the device demonstrated exceptional resilience, maintaining stable operation under high humidity conditions (80% relative humidity) and preserving its detection accuracy through prolonged testing exceeding 300 days, thereby confirming its robustness for real-world deployment.
The implications of this technology are profound. The low power requirements combined with multi-gas discrimination capability enable monolithic sensor installations that can radically reduce hardware costs and simplify deployment logistics in factories, power plants, and other industrial settings. Additionally, the device’s long operational lifespan and low maintenance demands make it an economical solution for continuous air quality monitoring in residential buildings, schools, and public spaces, providing real-time alerts that enhance occupant safety and regulatory compliance.
Furthermore, the sensor’s ability to operate efficiently at room temperature without heating makes it ideally suited for integration into wearable devices, such as smartphones and smartwatches. This integration opens the door to personalized environmental monitoring, empowering individuals with live data on hazardous gas exposure as they navigate their daily environments. The potential for such user-centered safety services could revolutionize personal health and safety, enabling rapid responses to gas leaks or toxic exposure scenarios.
Looking ahead, the KRISS team envisions ongoing refinements to this innovative sensing platform, focusing on optimizing catalyst compositions to tailor gas sensitivity profiles for specific industrial or environmental conditions. This customizable approach will facilitate deployment across diverse sectors with unique gas detection requirements, from chemical manufacturing plants to urban air pollution surveillance, enhancing both specificity and accuracy.
By addressing critical limitations of sensitivity, selectivity, power consumption, and safety trustworthiness, this visible light-driven indium sulfide/indium oxide heterojunction gas sensor array represents a paradigm shift in photonic gas sensor technology. It embodies a breakthrough that promises to redefine environmental monitoring infrastructure, reduce operational costs, and equip individuals with actionable data to safeguard health and wellbeing worldwide.
This pioneering research, supported by the Ministry of Science and ICT’s Nano and Materials Technology Development Program, reflects a collaborative triumph between KRISS and Seoul National University’s Department of Materials Science and Engineering. The full details of this landmark study were published in the prestigious journal Small, underscoring its scientific significance and anticipated broad impact within the global nanotechnology and sensor research community.
Subject of Research: Development of a visible light-driven heterojunction gas sensor array using Type-I In₂S₃/In₂O₃ nanostructures for selective multi-gas discrimination.
Article Title: Visible Light-Driven Heterojunction Array Based on Type-I In₂S₃/In₂O₃ for Selective Multi-Gas Discrimination
News Publication Date: 18-Dec-2025
Web References: http://dx.doi.org/10.1002/smll.202506056
Image Credits: Korea Research Institute of Standards and Science (KRISS)
Keywords
gas sensor, visible light LED, heterojunction, indium sulfide, indium oxide, multi-gas discrimination, low power consumption, room temperature operation, electronic nose, nanostructure, noble metal catalyst, air quality monitoring
