Too much salt can raise blood pressure and increase the likelihood of heart complications in people with hypertension and other cardiovascular conditions, according to the Georgia Institute of Technology. To help monitor salt intake, researchers there have developed a flexible and stretchable wireless sensing system designed to be worn comfortably in the mouth to measure the amount of sodium people consume.
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,” said Woon-Hong Yeo, PhD, MS, an assistant professor in the Woodruff School of Mechanical Engineering at the university. “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 it for up to a week while eating both solid and liquid foods including vegetable juice, chicken soup, and potato chips. The American Heart Association (AHA) reports that Americans on average eat more than 3,400 mg of sodium each day, far more than the 1,500-mg limit it recommends.
Also, according to an AHA survey of 1,000 adults, a third of the respondents couldn’t estimate how much sodium they eat, and 54% thought they eat less than 2,000 mg each day. The sodium system could address that challenge by helping users better track how much salt they consume, Yeo said.
“Our device could have applications for many different goals involving eating behavior for diet management or therapeutics,” he said.
Key to the sensor’s development was the 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 entire sensing and electronics package was conformally integrated onto a soft material that users can tolerate,” Yeo explained. “The sensor is comfortable to wear, and data from it can be transmitted to a smartphone or tablet. Eventually the information could go to a doctor or other medical professional for remote monitoring.”
The flexible design began with computer modeling to optimize the mechanical properties of the device for use in the curved and soft oral cavity. The researchers then used their model to design the nanomembrane circuitry and choose components. The device can monitor sodium intake in real time and record daily amounts. Using a smartphone or tablet application, it could advice users how much of their daily salt allocation they have consumed.
The device can communicate with a smartphone up to 10 meters away. Next, the researchers want to further miniaturize it and test it with users who have hypertension, obesity, or diabetes. They also want to eliminate the battery, which must be recharged daily. One option would be to power the device inductively, replacing the battery and circuit with a coil that could obtain power from outside the mouth.
The project grew out of a long-term goal of producing an artificial taste system that can sense sweetness, bitterness, pH, and saltiness. That work began at Virginia Commonwealth University, where Yeo was an assistant professor before joining Georgia Tech. The study, “Wireless, Intraoral Hybrid Electronics for Real-Time Quantification of Sodium Intake Toward Hypertension Management,” was published by the Proceedings of the National Academy of Sciences.