Multimodal Sensing Flexible E-textile System for Maternal Health Monitoring

In developing countries and low-income communities, predicting the timing of childbirth is critical due to high infant mortality rates linked to limited healthcare infrastructure. Early and accurate detection of labor can significantly reduce risks for both mothers and infants. Currently, predicting childbirth primarily relies on detecting uterine contractions through electromyography (EMG) signals or changes in pressure, typically measured by tocodynamometers (TOCO). While these techniques are effective and provide highly accurate results, these systems are often bulky, rigid, and involve separate sensors for different signals, making them impractical for continuous, wearable use.
In response to this challenge, we propose an innovative E-textile system that can be worn comfortably 24 hours a day and monitor maternal health through integrated sponge and textile electrodes that can simultaneously collect EMG and pressure signals. The soft and porous sponge, based on polydimethylsiloxane (PDMS), is fabricated using a sugar template to ensure biocompatibility, and its surface is coated with highly conductive poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) ink. The ink is formulated to maximize conductivity by preventing charge interactions between PEDOT and PSS molecules, and to enhance mechanical stability through cross-linking between PSS molecules using polyethylene oxide (PEO) in an optimized ratio followed by curing. This sponge electrode exhibits high compressibility and stretchability, allowing it to reliably transmit EMG signals to the collection board, even under external deformation. Additionally, the porous structure responds to pressure changes by altering both resistance and capacitance, an advantage that enables our innovative board to simultaneously measure both parameters, thereby amplifying signal collection. This sponge electrode exhibits high compressibility and stretchability, allowing it to reliably transmit EMG signals to the collection board, even under external deformation. Additionally, to enhance its applicability in everyday use, the sponge electrode is attached to the textile electrode using an ionic conductive bond, creating a flexible and wearable form factor.
For the textile electrode, the PEDOT:PSS and PEO mixture is formulated to achieve high mechanical stability, allowing direct coating onto fabric. The self-assembled monolayer (SAM) coating of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (FTOS) provides a hydrophobic layer, enhancing the electrode's resistance to sweat and moisture. By directly coating the ink onto nylon-based spandex textile, we demonstrate the potential for seamless integration into everyday clothing for continuous maternal health monitoring.
As a result, this system exhibits a significantly lower contact impedance of 4.41*10⁴ Ω*cm² and an enhanced signal-to-noise ratio (SNR) for EMG, reaching up to 26.23 dB, compared to flat textile electrodes. Additionally, it demonstrates high pressure sensitivity, with a resistance change of -0.65 (ΔR/R₀) under 277 Pa, and is capable of detecting wrist pulse signals, which are much weaker than uterine contraction signals. Furthermore, the effectiveness of this electrode system for maternal health monitoring was confirmed through a clinical patient study. We firmly believe that this sponge electrode system can provide reliable, everyday health monitoring for pregnant women.