Frequency-dependent shear impedance of the tectorial membrane
Frequency-dependent shear impedance of the tectorial membrane
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DOI：
10.1529/biophysj.107.124727
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发表时间：
2008-09-01
影响因子：
3.4
通讯作者：
Aranyosi, A. J.
中科院分区：
文献类型：
--
作者：
Gu, Jianwen Wendy;Hemmert, Werner;Aranyosi, A. J.
设计并批量制造了用于向生物组织施加剪切力的微尺度机械探针。这些探头被用来测量在两个维度的覆膜（TM）的剪切阻抗。在径向和纵向方向上施加力，频率范围为0.01-9 kHz，振幅为0.02-4 μ N。通过测量探针悬臂的偏转来确定所施加的力。径向TM阻抗在10 Hz时的幅值为63 +/- 28 mN.s/m，随频率下降16 +/- 0.4 dB/decade，恒定相位为-72 +/- 6度。在纵向方向上，阻抗在10 Hz时为36 +/- 9 mN.s/m，下降19 +/- 0.4 dB/decade，恒定相位为-78 +/- 4度。阻抗几乎是恒定的力的函数，除了在最高的力，它略有下降。这些结果表明，TM的粘弹性延伸到一个显着的音频频率范围内，与TM力学的多孔弹性解释一致。从这些测量中确定的剪切模量G'为17-50 kPa，这大于具有较低听觉频率范围的物种。该值表明，发束不能全局剪切TM，但最有可能导致大量TM运动。
Microscale mechanical probes were designed and bulk-fabricated for applying shearing forces to biological tissues. These probes were used to measure shear impedance of the tectorial membrane (TM) in two dimensions. Forces were applied in the radial and longitudinal directions at frequencies ranging from 0.01-9 kHz and amplitudes from 0.02-4 mu N. The force applied was determined by measuring the deflection of the probes' cantilever arms. TM impedance in the radial direction had a magnitude of 63 +/- 28 mN.s/m at 10 Hz and fell with frequency by 16 +/- 0.4 dB/decade, with a constant phase of -72 +/- 6 degrees. In the longitudinal direction, impedance was 36 +/- 9 mN.s/m at 10 Hz and fell by 19 +/- 0.4 dB/decade, with a constant phase of -78 +/- 4 degrees. Impedance was nearly constant as a function of force except at the highest forces, for which it fell slightly. These results show that the viscoelastic properties of the TM extend over a significant range of audio frequencies, consistent with a poroelastic interpretation of TM mechanics. The shear modulus G' determined from these measurements was 17-50 kPa, which is larger than in species with a lower auditory frequency range. This value suggests that hair bundles cannot globally shear the TM, but most likely cause bulk TM motion.