• Chyasnavichyus, Marius
• Young, Seth L.
• Barth, Friedrich G.
• Zlotnikov, Igor
• Fratzl, Prof. Dr. Dr. H. C. Peter
• Tsukruk, Vladimir V.
• Politi, Yael
• Erko, Maxim
• Fratzl, Peter

Abstract

<p>A strain-sensing lyriform organ (HS-10) found on all of the legs of a Central American wandering spider (Cupiennius salei) detects courtship, prey and predator vibrations transmitted by the plant on which it sits. It has been suggested that the viscoelastic properties of a cuticular pad directly adjacent to the sensory organ contribute to the organ's pronounced high-pass characteristics. Here, we investigate the micromechanical properties of the cuticular pad biomaterial in search of a deeper understanding of its impact on the function of the vibration sensor. These properties are considered to be an effective adaptation for the selective detection of signals for frequencies &gt;40 Hz. Using surface force spectroscopy mapping we determine the elastic modulus of the pad surface over a temperature range of 15-40 °C at various loading frequencies. In the glassy state, the elastic modulus was ∼100 MPa, while in the rubbery state the elastic modulus decreased to 20 MPa. These data are analyzed according to the principle of time-temperature superposition to construct a master curve that relates mechanical properties, temperature and stimulus frequencies. By estimating the loss and storage moduli vs. temperature and frequency it was possible to make a direct comparison with electrophysiology experiments, and it was found that the dissipation of energy occurs within a frequency window whose position is controlled by environmental temperatures.</p>

Topics

• impedance spectroscopy
• surface
• experiment
• positron annihilation lifetime spectroscopy
• Photoacoustic spectroscopy