A new wearable technology could change how we monitor unborn babies at home. PhD researcher Yijing Zhang (Department of Electrical Engineering) has developed a comfortable, portable garment that allows pregnant women to measure their baby's heartbeat without the need for sticky, uncomfortable gel-based electrode sensors or direct skin contact. The integrated dry electrodes work through clothing, making the process simple and suitable for everyday use.
"Current home monitors often work only through direct skin contact, and the gel applied to the skin can cause irritation. It doesn't feel comfortable and is less effective," Zhang explains.
Wearable garment
During her PhD research, she developed a wearable garment with multiple integrated electrodes and dedicated data-acquisition hardware built around a custom integrated-circuit chip. "Pregnant women can avoid the gel and even wear this over their own clothes and easily measure their unborn child's heartbeat," she says. Zhang compares the convenience of the garment to wearables (such as smartwatches) that we use today to measure health metrics, like heart rate.
Minimizing noise
To ensure that her wearable monitor works just as well as a traditional gel-based sensor, Zhang focused her research on preventing noise during measurements. "The heartbeat of an unborn child is weak, so you want as little interference as possible to be able to detect it properly. The influence of the mother's breathing and movement is significantly greater with this wearable dry sensor variant. Traditional sensors are more stable because there is more direct contact between the measuring device and the body."
Not only do human physiological responses lead to noise, but the electrodes and electronic circuitry of Zhang's wearable also interfere with the measurement process. The PhD researcher explored advanced techniques to reduce noise from these sources. In doing so, she introduced innovative solutions, including a hybrid amplifier structure and a fast reset scheme , to effectively mitigate this noise.
Testing
Her research is supported by the Eindhoven MedTech Innovation Center ( e/MTIC ). In collaboration with Maxima Medical Center ( MMC ), Zhang tested her system on more than 10 pregnant women, achieving a plausible outcome. MMC also provided feedback on the material used for the wearable garment.
Philips , another research partner, contributed to the technical aspects of the portable monitor. "The advantage of designing the device yourself is that you can adjust the design based on feedback during the process," notes Zhang.
Peace of Mind
Making home monitoring during pregnancy easier offers benefits to both expectant parents and hospitals. "It provides mothers with peace of mind in that they can easily check on the health of their unborn child. The data from home monitoring is then shared with the hospital, allowing for remote support to be provided. If something is wrong, they can intervene in time," Zhang explains.
It also saves time for both parties: parents don't have to visit the hospital for every check-up, and hospital staff can focus on other tasks. Zhang sees another advantage: "In countries where people live far from hospitals, this is an alternative to prenatal care."
Reliability
Zhang expects it will take another five to ten years to bring the portable home monitor to market, mainly due to medical device regulations. "Additionally, the reliability of this monitoring needs to be tested more thoroughly."
