$7 Gadget Finds Hidden Cameras With 94% Accuracy

Finding a hidden camera in your hotel room or rental just got easier, thanks to researchers who built a detector that costs less than a large pizza.

Scientists at KAIST in South Korea created SweepLED, a smartphone case attachment that spots concealed cameras with 94% accuracy in about five seconds. The entire device costs under $7 to build, making privacy protection accessible to anyone who travels.

Hidden cameras have become an unsettling reality in vacation rentals and hotel rooms, often disguised inside everyday objects like phone chargers, clocks, or picture frames. Most handheld detectors on the market rely on shining a light and looking for reflections, but they struggle because glass, metal, and shiny plastic all reflect light too. Travelers end up playing a frustrating guessing game, squinting at every suspicious glint.

SweepLED eliminates that guesswork with a simple but clever approach. Instead of moving both the light and viewing angle together like traditional detectors, it keeps the smartphone camera steady while sweeping LED light from different directions around the object.

That matters because camera lenses have internal structures like apertures, sensors, and layered glass that create unique reflection patterns as light hits them from different angles. Regular shiny surfaces just reflect light back without those telltale distortions.

The device records a short video of the light sweep, then runs it through an AI model trained to recognize lens-specific reflection patterns. When it spots those distinctive warping effects, it flags the location of a potential hidden camera.

Professor Jun Han led the research team at KAIST's School of Computing, collaborating with scientists from the National University of Singapore and Singapore Management University. They tested SweepLED against 30 common hotel room objects and achieved that 94% accuracy rate.

The timing couldn't be better. A recent study from University College London found that people using consumer hidden camera detectors still missed 59% of devices during testing. That's a scary gap when your privacy is on the line.

The Bright Side

What makes this breakthrough especially hopeful is how accessible it could become. At under $7 in materials, this isn't some luxury security gadget available only to wealthy travelers. The technology is simple enough that it could realistically turn into an actual product that everyday people can afford and carry in their luggage.

The research team presented their findings at ACM MobiSys 2026 earlier this year. While SweepLED isn't available for purchase yet, the straightforward design suggests it won't stay in the lab forever.

Privacy protection is becoming a real product anyone can slip into their suitcase.