What is the connection between moths and high technology? This connection is not merely ordinary, because moths have two highly sensitive antennae on their heads, which constitute highly sensitive olfactory organs.

These enable moths to navigate and find mates. How do such small amounts of pheromone molecules help? Scientists at the University of Twente discovered more about the shape of the antennae and their efficiency at different flight speeds – moths should avoid flying too fast.

According to research published in the Proceedings of the National Academy of Sciences, this moth offers some lessons for naturally inspired micro-sensors.

On the head of the moth, there are two pectinate antennae, which are highly complex olfactory organs. The visible branches are called rami, with very fine hairs known as sensilla, with a diameter of approximately 3μm.

This provides a structure capable of capturing pheromone molecules from the air; in this sensor, the sensilla use them to transmit chemical data to the moth's nervous system to help select its path. If researchers intend to develop sensors with such incredible qualities, what can be learned from nature?

The team analyzed the shape of the airflow and its effect relative to the antennae. Clearly, if the speed is too high or too low, the "navigation quality" of the antennae will not function properly. For optimal performance, moths must fly at moderate speeds.

Leakage

Samia cynthia are the species analyzed in this study. Researchers measured the dimensions of the moth antennae, then 3D printed a ramus slice with light-emitting diodes to conduct experiments at different speeds. One of the main conclusions of the study is that "leakage" plays a crucial role in success rate.

It relates to the volume of air passing through the antenna structure, relative to the maximum possible air volume. The moth's flight speed ranges from 0.5 to 3 m/s, but there is obviously an optimal capture capability.

When moths move quickly, more air flows through the antenna structure, but pheromones do not hit the sensilla because the "final part" must occur via diffusion. There is insufficient time as pheromones propagate through the antennae. Therefore, slower flight is highly effective.

Earlier studies indicated that the tips of Semilla collectively capture an "olfactory lens," thereby improving capture efficiency. This is believed to be related to the physicochemical behavior of the tip surfaces.

According to this new study, it is described in terms of mass transport conditions. Inspired by nature, cantilever arrays power many nano- and micro-sensors.

This study was conducted based on collaboration between the Robotics and Mechatronics Group at the University of Twente (Professor Gijs Krijnen) and the Institute for Insect Research located in Tours, France.