Drones are increasingly being used for disaster response, infrastructure inspection, and environmental monitoring. However, most drone systems rely primarily on cameras and other visual sensors, which can become ineffective in smoke, dust, darkness, or collapsed structures. Odor sensing could provide a valuable complementary capability by enabling drones to detect gas leaks and chemical emissions that cannot be identified through visual sensing alone. Yet a major challenge has limited their practical use of such biohybrid sensors: excised insect antennae gradually lose signal quality as they dry out and the electrical interface becomes unstable.
To address this challenge, researchers from Shinshu University and Chiba University have developed a water-retaining hydrogel electrode that stabilizes the interface between insect antennae and recording electrodes, extending the usable recording time of biohybrid odor sensors. These sensors record electroantennogram (EAG) signals—the electrical responses produced by insect antennae when exposed to odors. The study was made available online on July 2, 2026, and will be published in Volume 467, Part 1 of Sensors and Actuators B: Chemical on November 15, 2026. The research was led by Associate Professor Daigo Terutsuki from the Faculty of Textile Science and Technology at Shinshu University, together with graduate student Reina Omori, undergraduate student Kie Kondo, Associate Professor Yosuke Kageshima of Shinshu University, and Associate Professor Toshiyuki Nakata of Chiba University.
“ Improving how far an odor-tracking drone can search is only part of the challenge. Its biological sensor must also remain stable long enough to work on a moving platform. We therefore focused on the antenna–electrode interface and developed a hydrogel structure that helps maintain a hydrated contact environment for several hours ,” says Dr. Terutsuki.
To overcome these limitations, the electrode combines a hydrogel, a conductive gel layer, a gold-plated core, and a 3D-printed frame. The moisture-retaining hydrogel creates a stable environment around the antenna while maintaining reliable electrical coupling during EAG recording.
The team evaluated the hydrogel electrode using excised antennae from male silkworm moths ( Bombyx mori ). Under tested indoor, room-temperature conditions, the electrode maintained more than 92% of the initial EAG response amplitude after seven hours. By contrast, the conventional grooved gold-plated metal electrode fell below the study’s predefined 50% practical-usability threshold by four hours. Electrochemical impedance measurements supported more stable electrical coupling in the hydrogel electrode assembly during the first hour.
To examine whether the stabilized sensor could operate on a mobile platform, the researchers mounted it on a lightweight drone. During proof-of-concept experiments, the sensor successfully detected odor-evoked EAG signals, while in separate proof-of-concept free-flight tests, EAG threshold crossings triggered a programmed stop-and-advance sequence. Rather than demonstrating optimized odor-source localization, these experiments showed that the stabilized biohybrid interface can support drone-mounted odor sensing under the tested flight conditions.
By improving the stability of the antenna–electrode interface, the hydrogel addresses one of the key barriers to deploying insect-based odor sensors outside the laboratory. The hydrogel helps maintain a hydrated electrical contact, extending the usable EAG recording window for several hours. This longer recording window could facilitate future development of biohybrid sensing systems for mobile robotics and environmental monitoring.
The researchers highlight the potential impact of stable biohybrid odor sensing in real-world environments. “ In disaster-prone regions such as Japan, longer-lasting biological odor sensors could become a key component in future search-and-rescue systems after earthquakes,” shares Dr. Terutsuki. He adds, “ In industrial settings, they could enable mobile detection of gas leaks or chemical emissions in areas that are difficult or dangerous for humans to access .”
The study demonstrates how engineering a simple biohybrid interface can significantly improve the practicality of insect-derived odor sensors. By extending stable EAG recording and enabling proof-of-concept drone-mounted odor sensing, the work provides a foundation for future biohybrid sensing platforms that could support disaster response, hazardous chemical monitoring, infrastructure inspection, and environmental monitoring.
About Shinshu University
Shinshu University is a national university founded in 1949 and located nestling under the Japanese Alps in Nagano known for its stunning natural landscapes. Shinshu University was selected for the Forming Japan’s Peak Research Universities (J-PEAKS) Program by the Japanese government. This initiative seeks to promote the formation of university consortia that will enhance research capabilities across Japan.
Our motto, "Powered by Nature - strengthening our network with society and applying nature to create innovative solutions for a better tomorrow," reflects the mission of fostering promising creative professionals and deepening the collaborative relationship with local communities, which leads to our contribution to regional development by innovation in various fields. We’re working on providing solutions for building a sustainable society through interdisciplinary research fields: material science (carbon, fiber, and composites), biomedical science (for intractable diseases and preventive medicine), and mountain science, and aiming to boost research and innovation capability through collaborative projects with distinguished researchers from the world. For more information visit https://www.shinshu-u.ac.jp/english/ or follow us on X (Twitter) @ShinshuUni for our latest news.
About Associate Professor Daigo Terutsuki from Shinshu University
Dr. Daigo Terutsuki, an Associate Professor in the Faculty of Textile Science and Technology at Shinshu University and a Shinshu University Rising Star Researcher, works at the intersection of biohybrid robotics, chemical sensing, and biological interface engineering. He develops odor-sensing flying robots that integrate insect antennae with compact electronics and drones, aiming to give robots a biological sense of smell for environments where visual sensing is limited. In this study, his team addressed a critical bottleneck for real-world deployment: stabilizing the fragile antenna–electrode interface so that excised insect-antenna sensors can remain electrically reliable for several hours on mobile platforms.
Sensors and Actuators B Chemical
Experimental study
Animals
Engineering electroantennogram interfaces through agar-based hydrogels for multi-hour recording and drone-mounted biohybrid odor sensing
2-Jul-2026
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.