The computer mouse used to rely on an internal rubber ball to track movement; now it’s all done via lasers. Video game consoles and desktop computers once were turned on by a physical moving power switch; now it’s usually a capacitive touch panel. And it’s been more than a decade since Steve Jobs ushered in the modern era of smartphones that replaced a physical keyboard with a touch screen one.

The latest trend for smartphones is the removal of physical side buttons. Apple filed a few patent applications (01 & 02) covering this eventuality on iPhones and beyond. In the latter patent linked to above Apple noted that a "touch sensor layer may be formed on the inner surfaces of some or all of these opaque walls to provide the exterior surfaces of these portions of device with touch input capabilities."

While Apple has a few patent-pending inventions for this, Huawei was first to actually bring this idea to market when launching their Mate 30 Pro in September. Two screenshots about its side touch controls from our report covering the Huawei keynote are presented below.

Technically, Apple's recent patent application about touch being added to AirPods could also be used on other future Apple products including the iPhone, future eyeglasses, an HMD, headphones and more.

Just yesterday Apple was granted a patent describing touch controls being added to fabrics found on the outer ear cup of future over-the-ear headphones. So technically, Apple has the technology to bring this feature to future iPhones whenever they see fit to introduce it. 

This next-gen technology is already in use on Google’s three most recent Pixel phones, in which the left and right side of the chassis can be squeezed to launch Google Assistant.

Chinese smartphone brand Vivo’s Nex 3 flagship handset allowed users to adjust volume by pressing into the side bezel; and the company’s gaming-centric iQoo phones can turn its aluminum chassis into analogue shoulder buttons for gaming.

Chinese smartphone maker Xiaomi’s upcoming Mix Alpha will have no physical buttons at all – users power on the device by pressing into the side of the device, which is entirely covered by an OLED display.

Google, Vivo and Xiaomi use the technology from New Degree Technology for both side slide controls and squeeze-bezel features. The company is based in Shenzhen, southern China that specializes in building paper-thin, flexible sensors that can be embedded underneath a metal, glass, or plastic surface – basically any part of a smartphone.

These sensors can detect over 1,000 levels of pressure: the difference between a very light tap or a hard press, and everything in between.

The company’s founder, Hao Li, worked as an engineer at Motorola in the United States from 2001 to 2010. It was during his time working on display panels that he envisioned sensors that can detect varying degrees of pressure.

Apple first envisioned side controls on a glass iPhone form factor back in 2011 (published in 2013) as noted below. See side slider control as #406. Apple updated their invention on November 2, 2019.

Touch icons to launch apps on the side of an iPhone, like the Vivo phone photo above, was an invention granted to Apple in 2015.

One analyst noted that Apple’s 3D Touch sensors – which the company scrapped beginning with this year’s iPhone 11 series – were also less sophisticated, able to detect only two levels of pressure, while NDT’s sensors offer full analogue sensitivity.

The magic behind NDT’s tech comes from the tiny resistors in the sensors that detect 'deformation' pressure from the outside surface. Once the deformation has been registered, the resistors measure the pressure and output a voltage proportional to the amount of force that has been applied. In other words, it is turning physical analogue force into digital information for a device’s brain to calculate and determine action."

The analyst further noted that considering how much smartphone brands are pushing their vision of a sleek, all-screen device with no buttons, ports or bumps, there is likely to be more demand for force sensors to replace traditional buttons.

Apple is still considered the trendsetter in the smartphone world. The company’s engineers considered an iPhone with no physical buttons before deciding the technology wasn’t ready.

Perhaps by 2020 or 2021, the tech will mature enough for Apple’s liking. And once Apple does something, there will be no going back – physical buttons will be dead."