Smart Diaper

Indian American researchers at MIT, led by Pankhuri Sen, a research assistant in MIT’s AutoID Laboratory, created a cost-effective “smart” diaper that has an RFID sensor to notify a caregiver when a diaper is wet. (LinkedIn photo)

MIT researchers led by Indian Americans have created a “smart” diaper that has a sensor that can notify a caregiver when the diaper is wet.

According to an MIT report, if a baby wears a wet diaper too long it can cause painful rashes.

The MIT-led research group developed a “smart” diaper embedded with a moisture sensor that can alert a caregiver when a diaper is wet. When the sensor detects dampness in the diaper, it sends a signal to a nearby receiver, which in turn can send a notification to a smartphone or computer, the report notes.

The sensor consists of a passive radio frequency identification tag, which is placed below a layer of super absorbent polymer, a type of hydrogel that is typically used in diapers to soak up moisture, it notes.

When the hydrogel is wet, the material expands and becomes slightly conductive — enough to trigger the RFID tag to send a radio signal to an RFID reader up to 1 meter away, according to the report.

The researchers say the design is the first demonstration of hydrogel as a functional antenna element for moisture sensing in diapers using RFID.

They estimate that the sensor costs less than 2 cents to manufacture, making it a low-cost, disposable alternative to other smart diaper technology, MIT said.

Over time, smart diapers may help record and identify certain health problems, such as signs of constipation or incontinence. The new sensor may be especially useful for nurses working in neonatal units and caring for multiple babies at a time, it adds.

“Diapers are used not just for babies, but for aging populations, or patients who are bedridden and unable to take care of themselves,” Pankhuri Sen, a research assistant in MIT’s AutoID Laboratory, said in the report. “It would be convenient in these cases for a caregiver to be notified that a patient, particularly in a multibed hospital, needs changing.”

Sai Nithin R. Kantareddy, a graduate student in MIT’s Department of Mechanical Engineering and collaborator in the research, added: “This could prevent rashes and some infections like urinary tract infections, in both aging and infant populations.” Sen, Kantareddy and their colleagues at MIT, including Rahul Bhattacharryya and Sanjay Sarma, along with Joshua Siegel at Michigan State University, have published their results in the journal IEEE Sensors, the report said.

Sarma is MIT’s vice president for open learning and the Fred Fort Flowers and Daniel Fort Flowers Professor of Mechanical Engineering.

Many off-the-shelf diapers incorporate wetness indicators in the form of strips, printed along the outside of a diaper, that change color when wet — a design that usually requires removing multiple layers of clothing to be able to see the actual diaper, according to MIT.

RFID tags are low-cost and disposable, and can be printed in rolls of individual stickers, similar to barcode tags.

A typical RFID tag has two elements: an antenna for backscattering radio frequency signals, and an RFID chip that stores the tag’s information, such as the specific product that the tag is affixed to.

RFID tags don’t require batteries; they receive energy in the form of radio waves emitted by an RFID reader. When an RFID tag picks up this energy, its antenna activates the RFID chip, which tweaks the radio waves and sends a signal back to the reader, with its information encoded within the waves.

Sarma’s group has been enabling RFID tags to work not just as wireless trackers, but also as sensors, MIT said.

Sen envisions that an RFID reader connected to the internet could be placed in a baby’s room to detect wet diapers, at which point it could send a notification to a caregiver’s phone or computer that a change is needed.

For geriatric patients who might also benefit from smart diapers, she says small RFID readers may even be attached to assistive devices, such as canes and wheelchairs to pick up a tag’s signals, the institute report said.

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