Wearable sensor frees seniors from toilet accidents

JStories — In caregiving, one of the biggest challenges is assisting with excretion ー from diaper changes to trips to the toilet. This support, which takes up about 30 percent of caregiving time, affects not only the quality of life of elderly people, but also family relationships and personal dignity.

To ease this burden, Tokyo-based startup DFree, led by CEO Atsushi Nakanishi, has developed a wearable sensor that predicts when someone will need to urinate. The company’s name comes from “Diaper Free,” reflecting its mission to help people stay independent while reducing stress on caregivers.

The need for such solutions is urgent. As populations age, the share of people aged 65 and over is projected to nearly double worldwide, from 9.3 percent in 2020 to 17.8 percent in 2060. In Japan alone, the shortage of caregiving personnel is expected to reach 570,000 by 2040.

The device, also called DFree, is a small, cordless sensor worn on the lower abdomen. Using ultrasound from four directions, it tracks bladder expansion in 10 stages and sends smartphone notifications when it’s time to prepare for the toilet.

Until now, bladder monitoring was only possible with expensive medical scanners. DFree became Japan’s first wearable device to continuously track bladder status and give real-time alerts.

“The timing of notification differs for each person ー depending on the distance to the toilet, whether they need assistance, or whether they recognize the urge themselves,” says Nakanishi. “The biggest strength of DFree is its ability to set personalized thresholds.”

To establish those thresholds, the device is worn for about two weeks to collect baseline data. Nurses and social workers then review the information ー along with the user’s living conditions and health ー to set the most suitable notification levels.

Since April 2022, DFree has been covered under Japan’s Long-Term Care Insurance system, as a “specified welfare equipment” item, reducing the cost for users.

DFree is now in use at about 300 sites across Japan, including special nursing homes, geriatric health facilities, private care homes, and hospitals. It is also used in home care, and even as a support tool for toilet training among children with disabilities, including developmental disorders.

Feedback from facilities indicates that the device has improved the accuracy of caregiver prompts, cutting the number of guidance attempts by 1,110 per month and saving roughly 150 hours of staff time. One home-care user said: “My mother became withdrawn because of toilet accidents. Since starting to use DFree, the accidents have stopped, and she enjoys outings again. Most importantly, she’s smiling and talking with us.”

Nakanishi notes, “When toilet accidents reduce family conversations, it can affect cognitive function as well.”

The idea for DFree was born in 2013, when Nakanishi himself experienced incontinence while studying abroad in the United States. As he notes, urination and defecation are natural biological functions that don’t wait for the right time or place. “Preventing toilet accidents helps safeguard dignity, improve quality of life, and make better use of limited caregiving resources,” he says. “There are still challenges ー such as enabling measurement without a wearable device and predicting defecation as well as urination ー but we’ll keep working to help people remain independent for as long as possible.”

In January 2025, DFree formed a business alliance with Econavista, a Japanese company providing monitoring systems for elderly care based on sleep analysis. This partnership combines sleep and excretion data, supporting better rest, reducing fall risks, and easing caregiver workloads.

DFree is also moving toward system integration with Nemuri CONNECT, a monitoring support system for nursing and medical facilities developed by Paramount Bed. The Japanese company is a leader in hospital and elder-care beds and has also developed advanced technologies that allow staff to monitor residents’ sleep and safety without wearable devices. The integration is expected to be implemented within this fiscal year.

Looking ahead to next April, the company is preparing not only for domestic medical device certification but also for overseas expansion. That includes seeking approval from the U.S. Food and Drug Administration, a key step for entering the American market. “Aging is unavoidable, and healthcare is an issue that concerns everyone,” says Nakanishi. “We are targeting areas with large populations for sales, and will continue expanding into the U.S. and China.”

Translated by Anita De Michele | JStories

Edited by Mark Goldsmith

Top photo: Envato

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