MIT Researchers Build Smart Diapers That Sense Wetness

  • The new ‘smart’ diapers can notify a caregiver that it’s a time for a change. 
  • Unlike other diaper technology, it is both affordable and disposable.
  • It will help track and identify specific health problems, such as signs of incontinence or constipation.

The advent of the Internet of Things and miniaturization of sensing equipment has accelerated the development of wearable health devices. It is estimated that these devices will have an economic impact of $200 billion by 2025.

Now, researchers at MIT have come up with a ‘smart’ diaper embedded with a moisture sensor that can notify a caregiver that it’s a time for a change. Unlike other diaper technology, it is both affordable and disposable. The sensor attached in the diaper costs less than 2 cents to manufacture.

The technology will help track and identify specific health problems, such as signs of incontinence or constipation. It could be especially helpful for nannies caring for multiple babies at a time and for nurses working in neonatal units.

Smart diapers can also be used for older people and patients who are confined to bed or unable to take care of themselves. It could prevent rashes, urinary tract infections, and other bacterial infections.

How Does It Work?

The sensor in the smart diaper contains a passive RFID (radio-frequency identification) tag to detect and communicate wetness to a nearby reader, which can then send a notification to a computer or smartphone.

Typically, diapers are made of a layer of Super Absorbent Polymer (SAP, a subclass of hydrogel) so that they can easily soak up moisture. Researchers placed the sensor right below this layer.

A wet diaper changes the property of the SAP: it becomes a little bit conductive, triggering the RFID tag. Once triggered, the tag transmits a radio signal to an RFIF reader.

Reference: IEEE Sensors Journal | DOI:10.1109/JSEN.2019.2954746 | MIT

A conventional RFID tag contains two components:

  1. An antenna that backscatters RF signals.
  2. A chip for storing information of the tag, such as a unique identification number.

It doesn’t require batteries to operate. The RFID reader emits radio waves, which are strong enough to power an RFID tag. When tag detects radio signals, its antenna turns on the chip, which then modifies the radio signal (encodes information within radio waves) and transmits it back to the reader.

Smart Diapers Sense WetnessCredit: MIT

This is how individual smart diapers embedded with RFID tags can be detected and traced.

Advantages

Some existing diapers do come with wetness indicators; they include strips that alter color when wet. However, they aren’t as convenient as you think. To be able to see the actual diaper, you need to remove several layers of clothing.

A few manufacturers are focusing on Bluetooth-enabled wetness sensors that could be attached to the diaper’s exterior along with batteries. Although you would be able to detach and clean the sensor and reuse it in another diaper, such sensors would be quite expensive. Researchers estimate that each sensor would cost you $40.

The new smart diapers, on the other hand, are inexpensive and disposable. Just like barcode tags, it can be printed in rolls of individual stickers.

In current versions, the RFID tag can transmit a radio signal to an RFID reader situated 1 meter away. However, the range can be increased by including a tiny amount of copper into the sensor.

Read: Most Powerful Biosensor System Built With Copper and Graphene Oxide

The team will further explore the diagnostic capabilities of smart diapers, such as tracking changes in pH of SAP in the presence of urine, or glucose sensing for monitoring diabetes. Overall, the findings could enable a wide range of sensing capabilities on RFID tags using hydrogels.

Written by
Varun Kumar

Varun Kumar is a professional science and technology journalist and a big fan of AI, machines, and space exploration. He received a Master's degree in computer science from Indraprastha University. To find out about his latest projects, feel free to directly email him at [email protected] 

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