Flexible sensor matrix with dynamic channel weighting for improved estimation of the fetal heart rate by Doppler ultrasound

Electronic fetal heart-rate (fHR) monitoring is standard clinical practice to assess the fetal condition and to detect deviations from the normal fHR pattern. Typically, an ultrasound (US) transducer, operating in a pulsed-wave Doppler mode, measures the periodic motion and the resulting flow of the fetal heart, from which the fHR can be derived. However, as the fetus moves antepartum or during labour through the birth canal, the fetal-heart location (fHL) changes continuously. Consequently, the clinical staff needs to manually track the fHL and reposition the US transducer accordingly. In this research, a new flexible sensor matrix with multiple elements is designed; it allows measuring the fHR over a large range of possible fHLs. Further, a method for dynamic combination of the receiving channels is presented. This new method, compared to a standard combining technique, improves the signal-to-noise ratio (SNR) of the Doppler signal and, therefore, leads to more accurate fHR estimation.