Mechanical engineers Ken Kiger and Elias Balaras and entomologist Jeffrey Shultz identified a biological mechanism in the young mayflies that could enable sensors in stagnant environments, such as coal mines, buildings or underground public transit areas, to make air or water flow past them to aid in the detection harmful substances.
Young aquatic mayflies, or “nymphs,” enhance their respiration using gills, creating a flow of fresh water with the help of seven pairs of nearby gill plates that flap like a Venetian blind. The flow of fresh water is generated by the plate’s motion, directing water to the mayfly’s gills as efficiently as possible.
"By duplicating the action of the mayfly gill plates in a tiny robotic device, we hope to create a flow of air or water to sensors in stagnant environments, so they can operate more effectively," Kiger said.
That means potentially harmful substances can be detected faster in confined spaces, like mines.
Small But Effective
The researchers are exploring how the mayfly’s gill plates work and ways to construct a robotic version by attempting to duplicate and measure the gill plate movement in a virtual computer model.
They also are taking a closer look into something that scientists have known for a long time: at a sufficiently small size, an object is less affected by inertia than it is by the thickness (viscosity) of the water it is traveling through.
A tiny mayfly nymph is so small that the viscosity of the water stops such a current almost as soon as the gill plates stop. Once the mayfly grows to a certain size, though, it is capable of creating an inertial effect of its own. Its gills respond accordingly, which is a trait the researchers hope to replicate in their sensors.
"Mayfly sizes are right at the point where issues of viscosity and inertia switch in importance," Kiger said. "Depending on whether the weight or the thickness of the water is influencing its movement, the mayfly switches the way it pumps water to its gills."
The current trend in sensor technology is to strive for smaller and more compact devices to enhance their portability and reduce power consumption. As a result, traditional technology sensors will run into the same difficulty as experienced by the mayfly as the sensors reach smaller and smaller sizes: eventually a transition will occur where inertial flow mechanisms will become ineffective.
Studying how the mayfly deals with this transition can give researchers insight into how to better develop equivalent engineered sensors. The next step will be to construct a tiny artificial micro-robot that can reproduce the switchable gill action of the mayfly nymph.
Such a mechanism could be installed in sensors intended to detect unhealthy air in otherwise stagnant areas, such as in subway stations or mines.