Bio-hybrid drone uses silkworm moth antennae to navigate using smell

Technological advances have led to the development of drones with diverse applications, including navigation, gas sensing, infrastructure and transportation, imaging, and disaster response. Conventional navigation systems in drones rely on visual sensors like thermal imaging and light detection and ranging (LiDAR). However, environmental conditions such as low light, dust, and moisture can compromise their function, highlighting the need for more versatile alternatives.

In nature, animals, birds, and insects have an inherent navigation system based on their sense of smell that helps them locate food sources, evade predators, and attract potential mates, thereby promoting their overall survival. Insects, in particular male moths, can detect windborne sex pheromones from distances that, in some cases, extend to several kilometers through a process known as odor-source localization.

Bio-hybrid drones that integrate these biological sensory mechanisms with advanced artificial machinery hold significant promise in overcoming the challenges associated with existing robotic technologies.

In this context, a team of researchers led by Associate Professor Daigo Terutsuki from the Department of Mechanical Engineering and Robotics, Faculty of Textile Science and Technology, Shinshu University, Japan, along with Associate Professor Toshiyuki Nakata and Chihiro Fukui from Chiba University, Japan, have used silkworm moth antennae to develop a novel bio-hybrid drone capable of odor sensing and tracking. This study was published online in the journal npj Robotics on February 5, 2025.

Explaining their motivation behind the study, Dr. Terutsuki says, "Our team is continuing to develop bio-hybrid drones that utilize living insect antennae as odor sensor elements. In this research, we strive to incorporate the dynamic movements and mechanisms of living organisms to dramatically enhance the performance of our odor-tracking drones. We initiated this study with the belief that these advancements will enable more effective odor detection and broaden applications in rescue operations."

Previously, the researchers developed a bio-hybrid drone equipped with an electroantennography (EAG) sensor based on insect antennae with high sensitivity and specificity. However, its applications were limited by a short detection range of less than two meters. In the current study, the team has enhanced the primary version by further incorporating mechanisms that mimic the biological process in insects. Insects pause intermittently during the odor-tracking process to improve search precision. However, robotic odor-search models lack such pauses in their operation which may impact their range of detection.

To address this, the researchers introduced a "stepped rotation algorithm" that mimics insect pauses during odor sensing, significantly improving detection accuracy. They also redesigned the electrodes and EAG sensor to more effectively accommodate the structure of silkworm moth antennae. The seamless interface between the gain-modulable (responsive to electrical signal intensities) EAG sensor and the insect antennae significantly improved the performance and operability of the system.

Additionally, the team used a funnel-shaped enclosure to reduce airflow resistance and applied a conductive coating inside the enclosure to minimize noise interference from electrostatic charging. These modifications resulted in superior odor-source sensing under varied environmental conditions and odorant concentrations, with an effective detection range of up to 5 meters.

The diverse applicability of the odor-sensing bio-hybrid drone could potentially revolutionize gas leak detection in critical infrastructures, early fire detection, enhance public security at airports by detecting hazardous substances like drugs and explosives, and enable better disaster response by improving rescue operations.

This technology can be particularly useful in geographical regions that are more prone to natural disasters like earthquakes for rescue purposes. "Traditionally, search and rescue efforts have relied on manual visual searches due to the absence of a definitive technology capable of efficiently locating individuals in distress. The advanced bio-hybrid drone developed in this study has the potential to enable responders to rapidly locate survivors by tracking odors, ultimately saving more lives when every second counts." Dr.Terutsuki concludes.