Move over, smartwatches. Wearable devices designed to evaluate our bodies’ sleep patterns, track fitness, and check blood sugar levels are gaining popularity in the United States. Now, Fortune reports, tech companies are considering an even more futuristic gadget to monitor our health: ingestible sensors.

Several health startups are developing new technology that would allow users to swallow devices which either pass through the body or remain in the bloodstream to collect specific details about how the body is functioning in real time.

For example, health researchers say swallowable sensors could one day be used to detect blood alcohol levels and stop those who have had too much to drink from driving. Last year, Google announced it was developing a tracking pill capable of detecting diseases, such as cancer, at a cellular level.

The FDA has already approved several such devices for use. One is the Proteus Ingestible Sensor, which is embedded into pills and helps monitor how much medicine the body absorbs. Another device is the PillCam COLON, which allows patients who can’t do a colonoscopy to complete this cancer screening. As this pill passes through the digestive system, the device takes a series of photos and videos for doctors to evaluate.

Still, despite these high-tech health trackers already in use, experts say we’re several years away from ingestible trackers being made available to mainstream consumer markets.

For more information about available health and fitness trackers, click here and here.