Comparative Performance Evaluation of Fetal Movement-Detecting Wearable Sensors Using a Body-Worn Device

The inability of existing fetal movement (FM) detection methods, such as ultrasonography, to provide reliable in-home monitoring of FM has triggered a recent surge in efforts to design wearable sensor-based FM monitors. However, the relative performances of currently available FM-detecting wearable sensors and their possible synergies have not been quantified. To address this research gap, we present a detailed analysis of response characteristics and detection performances of the three most promising FM-detecting wearable sensors, namely the accelerometer, the acoustic sensor, and the piezoelectric diaphragm, both individually and in combination. A custom-made wearable belt with all three types of sensors was fabricated for home use. Maternal sensations of FM were contrasted to sensor output over a total of 33 hours of use with five pregnant participants. The results show that, for individual sensor types, the piezoelectric diaphragm outperformed (F
₁
score = 0.71) the accelerometer (F
₁
score = 0.65) and the acoustic sensor (F
₁
score = 0.65) significantly (p < 0.05). The combination of multiple sensor types provided notable performance improvements underscoring the importance of heterogeneity in the sensor combination. The best overall performance was achieved from the combination of all three sensor types (F
₁
score = 0.79), which was very closely followed by the combination of acoustic sensors and piezoelectric diaphragms (F
₁
score = 0.78) making it an efficient choice for wearable FM monitors. We believe the findings from this research will lead to an optimum design of a wearable FM monitor.