Touch screens are old news. Your next phone could be pressure-sensitive everywhere

Ultrasonic, pressure-sensitive touch technology is ready to go, and could make for button-free gadgets and wearables where every part is a touch surface.

Scott Stein Editor at Large
I started with CNET reviewing laptops in 2009. Now I explore wearable tech, VR/AR, tablets, gaming and future/emerging trends in our changing world. Other obsessions include magic, immersive theater, puzzles, board games, cooking, improv and the New York Jets. My background includes an MFA in theater which I apply to thinking about immersive experiences of the future.
Expertise VR and AR, gaming, metaverse technologies, wearable tech, tablets Credentials
  • Nearly 20 years writing about tech, and over a decade reviewing wearable tech, VR, and AR products and apps
Scott Stein
3 min read

The Sentons developer phone prototype: ultrasonic touch, everywhere.

Scott Stein/CNET

I've seen touch-sensitive areas on  phones and wearable devices before. But I've never seen an entire phone case become a touch surface. That's exactly what San Jose startup Sentons is trying to do, with ultrasonics that work like sonar to register touch and pressure anywhere on a gadget's surface. The possibilities seem incredibly weird, and extremely useful.

In my hands was a metal-cased phone, with no buttons. I scrolled through a browser, by running my finger down the side of the phone. Then, I adjusted the volume by pressing down on areas, which became my volume buttons. Now the camera app is opened, and suddenly the top edge becomes my shutter button. This is amazing stuff. 

Sentons already has one phone using its technology: the Asus ROG Phone II gaming phone has "air triggers" at the top that are pressure-sensitive touch zones. Vibrating haptics give feedback when they're pressed. Playing a first-person shooter on the phone in a demo, the trigger zones feel as useful as analog buttons.


The Asus Rog II, and its air triggers (also ultrasonic and pressure-sensitive).

Scott Stein/CNET

Sentons sees a case for far more than gaming, though. This ultrasonic technology could work on any surface, or any shape, in what the company says could be a wide range of materials: metal, wood, leather. Pressure sensitivity can range from 5 grams to 5 kilograms of force, which sounds shockingly robust.

I ask about whether this tech could even become some sort of future replacement for Apple's now-departed 3D Touch screen tech. Right now, Sentons is staying away from screens, and focusing on every other part of phones and electronics. Maybe screens could be next. Someday, but not now: the display is already "more heavily occupied," Sentons CEO Jess Lee said in a meeting where I demoed the tech.

The technology works by using transducers that run under the body of a phone or other device: I see the inside of the company's dev kit phone case, which uses a spidery array of thin wires. The ultrasonic pings form a map of the device surface, and can detect pressure, touch, and begin to understand context, like whether you're holding the phone or not, which can work to bring up specific touch mappings or even deactivate it in your pocket so there won't be accidental virtual button presses.


Sentons' developer phone isn't exciting-looking, but it's made to explore how the tech could work for other interested companies.

Scott Stein/CNET

Sentons tech is slated to be in several other phones by the end of the year, and Lee sees wearables and cameras as a big interest area, too. The ultrasonic touch-sensitive tech is waterproof, so it could be perfect for replacing buttons on underwater cameras or swim-friendly watches. Lee also suggests the tech could work into devices like blood pressure cuffs, detecting whether a cuff has the correct fit.

What seems possible, maybe, is integrating this tech into fabric or wearables, much like Google's Jacquard tech does in a limited way in smart clothing like Levi's jackets or backpack straps. It's not clear how flexible a device could be while using this tech, which makes me wonder about it working for super-flexible phones, although the ultrasonic tech is made to keep pinging and changing its surface map over time, to account for possible damage or dings.

Watch this: Asus ROG Phone 2 has the first 120Hz OLED screen

While the ultrasonic tech is made to work with skin contact, wearing gloves should be fine too, although I haven't tested to confirm. The one area that's a challenge, according to Lee: "Gels are hard."

My mind races to things like earbuds, or connected styli like Samsung's S-Pen or the  Apple Pencil , or smart glasses, where touch controls could be fitted into unusual geometries. For now, Sentons is starting with a developer phone and a platform called SurfaceWave for building gestures and interactions on future devices.

Much like Google's radar-based Soli tech on the Pixel 4, the world of ambient and gesture interfaces requires a new language, and it's hard to get feedback without screens. Sentons' tech could at least benefit from haptics, offering vibrating interaction along with pressure to create a feeling of tactile interaction. Maybe, in AR or VR, that could be used to create new types of touch controls. That certainly seems to be Lee's plan, at least.