低频低强度超声场中玻璃微管机械作用研究

Mechanical effect of glass micropipettes in low-frequency low-intensity ultrasonic field

玻璃微管电极是迄今为止记录神经元微弱电信号最精密的工具,目前已有许多学者将其应用在超声神经刺激研究领域,但其适用性却还未得到检验。通过粒子冲击试验研究了玻璃微管尖端的液体流动,发现频率为500 kHz的低强度超声脉冲能在其尖端激发出强烈的尖锐边缘声流,且声流的影响范围达到数百微米;并利用光学显微图像研究了超声引起的玻璃微管尖端的横向振动,发现尖玻璃微管尖端产生的横向振动幅度也可达到微米量级。试验结果表明,使用传统的玻璃微电极作为超声神经刺激的记录工具可能会对被研究的神经组织带来额外的机械刺激,从而严重干扰超声刺激的试验结果。

The glass microelectrode is the most precise tool for recording the weak electrical signals of neurons by far. At present, it has been widely used in the field of ultrasound neuronal stimulation research, but the applicability of glass microelectrodes has not been tested. The particle impacting experiment was used to study the liquid flow at the glass micropipette tips. It was found that lowintensity ultrasound pulse with a frequency of 500 kHz can evoke a strong sharp-edge acoustic streaming at the glass micropipette tips, and the influence range of acoustic streaming reaches hundreds of microns. The transverse vibration of the glass micropipette tips caused by the ultrasound was studied by optical microscope image, and it was found that the amplitude of the transverse vibration of the sharp glass micropipette tips can also reach the order of micrometers. The experimental results indicate that if the traditional glass microelectrodes are used as a recording tool for ultrasound neuronal stimulation, it may bring additional mechanical stimulation to the nerve tissue under study, which will seriously interfere with the experimental results of ultrasound stimulation.