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The intraoral electronics with a sodium sensor is based on a breathable elastomeric membrane that resembles a dental retainer. The ultrathin device is flexible and stretchable and can wirelessly transmit data up to 10 m. (Credit: Rob Felt, Georgia Tech)

To help monitor salt intake, researchers have developed a flexible and stretchable wireless sensing system designed to be comfortably worn in the mouth to measure the amount of sodium a person consumes.

Based on an ultrathin, breathable elastomeric membrane, the sensor integrates with a miniaturized flexible electronic system that uses Bluetooth technology to wirelessly report the sodium consumption to a smartphone or tablet. The researchers plan to further miniaturize the system – which now resembles a dental retainer — to the size of a tooth.

“We can unobtrusively and wirelessly measure the amount of sodium that people are taking in over time,” explains Woon-Hong Yeo, an assistant professor in the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “By monitoring sodium in real-time, the device could one day help people who need to restrict sodium intake and learn to change their eating habits and diet.”

The device has been tested in three adult study participants who wore the sensor system for up to a week while eating both solid and liquid foods including vegetable juice, chicken soup and potato chips.

The sodium sensing system could address that challenge by helping users better track how much salt they consume, Yeo says. “Our device could have applications for many different goals involving eating behavior for diet management or therapeutics,” he adds.

Key to development of the intraoral sensor was replacement of traditional plastic and metal-based electronics with biocompatible and ultrathin components connected using mesh circuitry. Sodium sensors are available commercially, but Yeo and his collaborators developed a flexible micro-membrane version to be integrated with the miniaturized hybrid circuitry.

The device can monitor sodium intake in real time and record daily amounts. Using a smartphone or tablet application, the system could advise users planning meals how much of their daily salt allocation they had already consumed. The device can communicate with a smartphone up to 10 m away.

Next steps for the sodium sensor are to further miniaturize the device and test it with users who have the medical conditions to address: hypertension, obesity, or diabetes.

The researchers would like to do away with the small battery, which must be recharged daily to keep the sensor in operation. One option would be to power the device inductively, which would replace the battery and complex circuit with a coil that could obtain power from a transmitter outside the mouth.

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