Bat wings could inspire better aircraft design

Scientists have found for the first time that a unique array of sensory receptors in the wing provides feedback to bats during flight, an advance that could inspire a better aircraft design.
The findings also suggest that neurons in the bat brain respond to incoming airflow and touch signals, triggering rapid adjustments in wing position to optimise flight control.
"This study provides evidence that the sense of touch plays a key role in the evolution of powered flight in mammals," said co-senior study author Ellen Lumpkin, from the Columbia University.
"This research also lays the groundwork for understanding what sensory information bats use to perform such remarkable feats when flying through the air and catching insects.

"Humans cannot currently build aircrafts that match the agility of bats, so a better grasp of these processes could inspire new aircraft design and new sensors for monitoring airflow," said Lumpkin.
Bats must rapidly integrate different types of sensory information to catch insects and avoid obstacles while flying.

The contribution of hearing and vision to bat flight is well established, but the role of touch has received little attention since the discovery of echolocation.
Cynthia Moss and co-author Susanne Sterbing-D'Angelo of The Johns Hopkins University discovered that microscopic wing hairs stimulated by airflow are critical for flight behaviours such as turning and controlling speed.

But until now, it was not known how bats use tactile feedback from their wings to control flight behaviours.
In the new study, the Lumpkin and Moss labs analysed, for the first time, the distribution of different sensory receptors in the wing and the organisation of the wing skin's connections to the nervous system.
Compared to other mammalian limbs, the bat wing has a unique distribution of hair follicles and touch-sensitive receptors, and the spatial pattern of these receptors suggests that different parts of the wing are equipped to send different types of sensory information to the brain.
"While sensory cells located between the "fingers" could respond to skin stretch and changes in wind direction, another set of receptors associated with hairs could be specialised for detecting turbulent airflow during flight," said Sterbing-D'Angelo.

Moreover, bat wings have a distinct sensory circuitry in comparison to other mammalian forelimbs. Sensory neurons on the wing send projections to a broader and lower section of the spinal cord, including much of the thoracic region.
In other mammals, this region of the spinal cord usually receives signals from the trunk rather than the forelimbs.
This unusual circuitry reflects the motley roots of the bat wing, which arises from the fusion of the forelimb, trunk, and hindlimb during embryonic development.
The study was published in the journal Cell Reports.