Supplementary material from "A parametric finite element model of leg campaniform sensilla in Drosophila to study CS location and arrangement."

Campaniform sensilla (CS) are mechanosensors embedded in the cuticle of insects. They are often found at locations near the joints of leg segments. On legs, CS are generally considered to respond directionally to cuticle bending during legged locomotion. It is currently unclear how CS locations affect strain levels at the CS, but this information is crucial for understanding how CS respond to stimuli. Here we present a parametric finite element model of the femoral CS field for Drosophila hind legs with twelve general and seven CS specific parameters each. This model allows testing how changes in CS location, orientation, and material property affect strain levels at each CS. We used experimentally acquired kinematic data and computed ground reaction forces to simulate in vivo-like forward stepping. The displacements found in this study at the physiological CS field location nearby the trochantero-femoral joint are smaller than those necessary for conformation changes of ion channels involved in signal elicitation. Also, variation of material properties of the CS had little influence on displacement magnitudes at the CS cap where the sensory neuron attaches. Thus, our results indicate that ground reaction forces alone are unlikely to serve CS field activation during forward walking.