In the past 15 months, Dr. Jessie Gaeta has lost count of how many people have overdosed on opioids in the public bathrooms of her South End clinic for the homeless.

But none of the victims died, Gaeta said. For that she credits a new piece of technology: an anti-motion detector linked to an alarm system that alerts staff if bathroom occupants are motionless.

“It’s practically an everyday occurrence,’’ said Gaeta, the chief medical officer of Boston Health Care for the Homeless Program, across the street from Boston Medical Center. “The solution has been a godsend, really.’’

The sensors, designed by an Andover-based electrician and installed in four of the bathrooms, have alerted workers to two to five overdoses every week since the devices were installed in March 2017, Gaeta estimated.

The alarms are an example of the creative ways health care professionals are using technology to combat the opioid crisis, as overdose deaths continue to plague the region.

The system is relatively simple: As soon as someone enters one of the public bathrooms and locks the door, a motion detector turns on. If it does not detect any motion for two minutes and 50 seconds, a loud alarm sounds and a strobe light flashes above the door.

A security guard, or any staff member in the area, immediately checks on the restroom to see if everything is OK. Almost every time, Gaeta said, the person inside has overdosed and is found nonresponsive.

“Many of the overdoses . . . are happening literally right at the point of injection’’ due to the potency of opioids like fentanyl, Gaeta said. “How would we even manage watching the bathrooms without this system? It would be very hard.’’

Once the alarm goes off, staff members are able to administer naloxone (often known by its trade name Narcan), call 911, and offer treatment services provided by the center.

“Every other week someone will come up to me and say, ‘John you saved another person this week,’ ’’ the electrician, John King, said. “It makes me feel good; I’m glad that I’m able to do this.’’

King, who has done electrical work at the facility for more than 20 years, first installed sensors in two lobby bathrooms last March after the center’s staff asked him to come up with a way to monitor the bathrooms for overdoses. He has since made slight upgrades to them and installed two more sensors in bathrooms near the program’s clinic.

The sensor is unassuming: small, white, and circular; it could pass for a smoke detector.

While the center had not seen any overdose deaths before installing the detectors, Gaeta said, there were close calls.

“We were just really fearful that we would lose someone,’’ she said.

Last year, more than 2,000 people in Massachusetts are estimated to have died from an opioid-related overdose, according to the state Department of Public Health. Boston alone saw 266 opioid-related deaths last year.

The center “could see the deaths coming from other facilities around the state and the country, and they just didn’t want to have anybody die from an overdose,’’ King said, recalling his conversations with staff. “Everybody was worried about it, because they felt like sooner or later it would happen.’’

The state does not keep data on how many opioid-related deaths specifically occur in public restrooms, according to a spokeswoman for the DPH. But for years, local health officials have identified them as frequent, dangerous hot spots for overdoses.

“They’re very scary, because they’re happening behind closed doors, which makes sense,’’ Gaeta said. “People are seeking places to inject that are private because it’s illegal and they don’t want to be arrested, so when they’re in public, they’re seeking private places.’’

The bathrooms are especially sought out by homeless people who do not have access to a shelter during the day. Despite the frequent overdoses, the center decided to keep the public bathrooms open for that reason.

King acknowledged that the system occasionally has false alarms, if someone falls asleep in the bathroom, for example. Overall, he said, the system for single-use bathrooms has been refined and works well.

“It does micro-motion, so if you’re sitting on the toilet and you just move your arm, your hand, the timer restarts,’’ he said.

King is working on getting a patent for the device, and hopes to soon design an alarm system that works for multistall bathrooms. Dane County in Wisconsin purchased one of the sensors to use in a bathroom in a resource center in Madison, according to King.

He has been asked to look at other facilities in the Boston area, but so far none fit his production abilities, he said.

“We’re not a big company; I could design more scenarios, but I don’t have the resources,’’ he said.

The Boston Public Health Commission has identified public bathroom overdoses as a problem and administers training for local businesses on how to prevent opioid-related deaths.

“CHECK YOUR RESTROOMS,’’ a poster released by the commission states. “Your actions could help save a life.’’

J.D. Capelouto can be reached at jd.capelouto@globe.com. Follow him on Twitter @jdcapelouto.