Goovaerts H G, van Geijn H P, Rompelman O, Mantel R, Swartjes J M
Department of Medical Physics, Free University, Amsterdam, The Netherlands.
Med Biol Eng Comput. 1991 Jul;29(4):358-64. doi: 10.1007/BF02441655.
A new transducer has been developed, based on an inductive principle, for recording fetal movements and sounds. The compliance of this transducer, the INductive PHOno-sensor (INPHO), can be matched to that of the maternal abdomen to provide an optimal transfer of displacement between maternal abdomen and transducer. In this manner, it is possible to detect fetal breathing movements by digital filtering of the INPHO signal in a frequency band between 0.5 and 2.0 Hz. Singular breathing movements can be detected and this was verified by real time ultrasound imaging. The INPHO transducer shows a flat (+/- 1.5 dB) frequency response between 0.2 and 200 Hz. The signal-to-noise ratio of the transducer system is better than 95 dB, and enables very weak movements and sounds to be detected. Spectral analysis of the processed signal shows that modulation of fetal breathing by maternal breathing takes place. The measuring setup allows for the quantitative assessment of fetal respiratory sinus arrhythmia.
一种基于感应原理的新型换能器已被开发出来，用于记录胎儿的运动和声音。这种换能器，即感应式胎儿声音传感器（INPHO）的顺应性，可以与孕妇腹部的顺应性相匹配，以在孕妇腹部和换能器之间实现位移的最佳传递。通过这种方式，在0.5至2.0赫兹的频带内对INPHO信号进行数字滤波，就有可能检测到胎儿的呼吸运动。可以检测到单个呼吸运动，这已通过实时超声成像得到证实。INPHO换能器在0.2至200赫兹之间呈现出平坦（±1.5分贝）的频率响应。换能器系统的信噪比优于95分贝，能够检测到非常微弱的运动和声音。对处理后的信号进行频谱分析表明，孕妇呼吸会对胎儿呼吸产生调制作用。该测量装置允许对胎儿呼吸性窦性心律失常进行定量评估。
