An inexpensive sensing glove may be able to lend a helping hand during labor and delivery in developing countries.
The glove is designed to transmit data on fetal position and force applied to the fetal head, and the data is then provided in real time on a smartphone app. The technology may be invaluable in preventing obstructed labor and stillbirth in low-resource regions, according to a new study, published in the journal Frontiers in Global Women's Health.
According to the researchers, 98% of stillbirths occur in low- and middle-income countries where more advanced medical technologies and skilled healthcare workers are not always available. They say obstructed labor, where the position or size of the fetus blocks its passage through the birth canal, is a major factor underlying this issue. Doctors can remedy this situation using various techniques, but they first need to identify the problem, preferably as early as possible. The motivation behind this study was to create a low-cost solution for doctors in low-resource regions.
Behind the design
The researchers began with a simple surgical glove as the basis for this technology. They printed flexible pressure and force sensors onto the glove’s fingertips. These sensors consist of metal-oxide nanocomposites that can generate an electric current when touching or rubbing against objects. The researchers ensured that the sensors were thin enough that they would not interfere with a doctor’s sense of touch. A second surgical glove can be worn over the team’s glove, to keep things sterile in the vaginal cavity. The researchers also developed a smartphone app, which allows clinicians to view the sensor data in real time. Each sensing glove costs less than $1 to produce.
Image courtesy of Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London via Frontiers in Global Women's Health
The device consists of flexible pressure and force sensors mounted onto the fingertips of a surgical glove, and flexible interconnects which were directly printed on the glove (Figure 1A above). The sensors were integrated by spray coating a metal-oxide nanocomposite onto the fingertip of the glove. The sensors work on the principle of triboelectricity, which is a type of contact electrification which occurs when two materials come into contact or are rubbed against each other. This contact electrification coupled with electrostatic induction is what enables the sensors to produce a current when making contact/rubbing against a material. The sensors and interconnects were tested on surgical gloves of the following typical materials: latex, nitrile, polyisoprene, and vinyl. The total cost of materials used to fabricate the sensors and interconnects is less than $1 per glove. For sterility purposes, the glove was covered by a standard sterile surgical glove routinely used in practice (Figure 1B above).
A customized wireless sensor node (WSN) was also designed to extract real-time data from the sensorized glove (Figures 1C, D above). This WSN is based on a four-layer printed circuit board that includes an nRF51 Bluetooth module (BLE4.0), with an analog signal-conditioning front-end circuitry (for triboelectric sensors) to deal with the signal dynamic range during wireless data transmission. The WSN connects to a phone app developed for real-time data display on the mobile phone screen. The app was developed using the MIT App Inventor platform. This platform has the functionality to create a gateway between the two hardware devices (mobile phone and WSN) and to create a mobile app. This mobile app shows the data converted and transmitted by the customized WSN. The real-time data is displayed on a mobile phone screen through the app. The app also saves this real-time data for further analysis (Figure 1E above).
Testing the sensing glove technology
To test the system, the researchers created models of a baby’s head from silicone elastomer, which replicated the delicate surface structures of the real thing. An experienced obstetrician performed mock vaginal examinations using the sensing glove and silicone heads, to test whether the system could identify features that would indicate the fetal position and measure the force applied to the head.
The sensing glove successfully indicated the joints between the "bones" of the model heads with a jump in electrical current as the glove’s finger passed over them. This would allow a clinician to determine where these joints are, and therefore calculate the orientation of the fetus. The glove also successfully sensed the force applied to the heads, providing real-time data on the smartphone app.
Translating the technology
The researchers plan to conduct trials in humans to determine whether the glove can provide the same information in real-world conditions. In addition to providing a simple and inexpensive early-warning system for obstructed birth in low-resource regions of the world, the technology may also act as a valuable training tool for clinicians in such regions.